Atkore (ATKR) 10-Q8 May 232023 Q2 Quarterly reportFinancial data

Company Profile

Cover

Cover - shares	6 Months Ended
Cover - shares	Mar. 31, 2023	May 04, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	001-37793
Entity Registrant Name	Atkore Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	90-0631463
Entity Address, Address Line One	16100 South Lathrop Avenue
Entity Address, City or Town	Harvey
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60426
City Area Code	708
Local Phone Number	339-1610
Title of 12(b) Security	Common Stock, $.01 par value per share
Trading Symbol	ATKR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		38,559,667
Entity Central Index Key	0001666138
Document Fiscal Year Focus	2023
Amendment Flag	false
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--09-30

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Income Statement [Abstract]
Net sales	$ 895,934	$ 982,573	$ 1,729,755	$ 1,823,374
Cost of sales	543,052	566,157	1,042,520	1,052,150
Gross profit	352,882	416,416	687,235	771,224
Selling, general and administrative	98,201	88,918	188,178	167,069
Intangible asset amortization	14,790	8,701	27,586	16,930
Operating income	239,891	318,797	471,471	587,225
Interest expense, net	8,475	7,514	17,963	14,432
Other (income) and expense, net	3,858	(807)	3,899	(1,115)
Income before income taxes	227,558	312,090	449,609	573,908
Income tax expense	53,364	78,613	101,923	135,588
Net income	$ 174,194	$ 233,477	$ 347,686	$ 438,320
Net income per share
Basic (in dollars per share)	$ 4.37	$ 5.14	$ 8.63	$ 9.51
Diluted (in dollars per share)	$ 4.31	$ 5.08	$ 8.52	$ 9.39

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 174,194	$ 233,477	$ 347,686	$ 438,320
Other comprehensive (loss) income, net of tax:
Change in foreign currency translation adjustment	2,462	(2,554)	13,724	(4,012)
Change in unrecognized loss related to pension benefit plans	201	125	263	250
Total other comprehensive (loss) income	2,663	(2,429)	13,987	(3,762)
Comprehensive income	$ 176,857	$ 231,048	$ 361,673	$ 434,558

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Current Assets:
Cash and cash equivalents	$ 354,342	$ 388,751
Accounts receivable, less allowance for current and expected credit losses of $2,415 and $2,544, respectively	533,712	528,904
Inventories, net	416,050	454,511
Prepaid expenses and other current assets	95,379	80,654
Total current assets	1,399,483	1,452,820
Property, plant and equipment, net	443,291	390,220
Intangible assets, net	424,910	382,706
Goodwill	310,686	289,330
Right-of-use assets, net	95,950	71,035
Deferred tax assets	2,025	9,409
Other long-term assets	3,344	3,476
Total Assets	2,679,689	2,598,996
Current Liabilities:
Accounts payable	258,051	244,100
Income tax payable	4,760	5,521
Accrued compensation and employee benefits	34,037	61,273
Customer liabilities	69,095	99,447
Lease obligations	14,566	13,789
Other current liabilities	87,396	77,781
Total current liabilities	467,905	501,911
Long-term debt	761,612	760,537
Long-term lease obligations	81,767	57,975
Deferred tax liabilities	16,283	15,640
Other long-term liabilities	13,327	13,146
Total Liabilities	1,340,894	1,349,209
Equity:
Common stock, $0.01 par value, 1,000,000,000 shares authorized, 38,937,691 and 41,351,350 shares issued and outstanding, respectively	390	415
Treasury stock, held at cost, 260,900 and 260,900 shares, respectively	(2,580)	(2,580)
Additional paid-in capital	497,810	500,117
Retained earnings	879,334	801,981
Accumulated other comprehensive loss	(36,159)	(50,146)
Total Equity	1,338,795	1,249,787
Total Liabilities and Equity	$ 2,679,689	$ 2,598,996

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Statement of Financial Position [Abstract]
Accounts receivable, allowance for current and expected credit losses	$ 2,415	$ 2,544
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	38,937,691	41,351,350
Common stock, shares outstanding (in shares)	38,937,691	41,351,350
Treasury stock (in shares)	260,900	260,900

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022
Operating activities:
Net income	$ 347,686	$ 438,320
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	54,566	40,040
Deferred income taxes	6,910	(4,270)
Stock-based compensation	12,133	9,555
Amortization of right-of-use assets	8,234	6,489
Other non-cash adjustments to net income	(4,562)	7,474
Changes in operating assets and liabilities, net of effects from acquisitions
Accounts receivable	(502)	(95,016)
Inventories	47,126	(127,790)
Prepaid expenses and other current assets	(8,961)	(14,490)
Accounts payable	(2,279)	19,617
Accrued and other liabilities	(61,771)	(37,972)
Income taxes	5,860	(80,415)
Other, net	(1,044)	(383)
Net cash provided by operating activities	403,396	161,159
Investing activities:
Capital expenditures	(72,690)	(25,343)
Proceeds from sale of properties and equipment	1	642
Acquisition of businesses, net of cash acquired	(83,385)	(36,098)
Net cash used in investing activities	(156,074)	(60,799)
Financing activities:
Issuance of common stock, net of shares withheld for tax	(14,434)	(24,399)
Repurchase of common stock	(269,168)	(261,173)
Finance lease payments	(660)	0
Net cash used for financing activities	(284,262)	(285,572)
Effects of foreign exchange rate changes on cash and cash equivalents	2,531	(678)
Decrease in cash and cash equivalents	(34,409)	(185,890)
Cash and cash equivalents at beginning of period	388,751	576,289
Cash and cash equivalents at end of period	354,342	390,399
Supplementary Cash Flow information
Capital expenditures, not yet paid	8,129	4,815
Operating lease right-of-use assets obtained in exchange for lease liabilities	30,430	1,148
Acquisitions of businesses, not yet paid	$ 14,125	$ 2,864

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance at beginning of period (in shares) at Sep. 30, 2021		45,997
Balance at beginning of period at Sep. 30, 2021	$ 864,736	$ 461	$ (2,580)	$ 506,921	$ 388,660	$ (28,726)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	204,843				204,843
Other comprehensive income (loss)	(1,333)					(1,333)
Stock-based compensation	3,427			3,427
Issuance of common stock, net of shares withheld for tax (in shares)		355
Issuance of common stock, net of shares withheld for tax	(24,505)	$ 4		(24,509)
Repurchase of common stock (in shares)		(958)
Repurchase of common stock	(104,547)	$ (10)			(104,537)
Balance at end of period (in shares) at Dec. 24, 2021		45,394
Balance at end of period at Dec. 24, 2021	942,621	$ 455	(2,580)	485,839	488,966	(30,059)
Balance at beginning of period (in shares) at Sep. 30, 2021		45,997
Balance at beginning of period at Sep. 30, 2021	864,736	$ 461	(2,580)	506,921	388,660	(28,726)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	438,320
Other comprehensive income (loss)	(3,762)
Balance at end of period (in shares) at Mar. 25, 2022		43,879
Balance at end of period at Mar. 25, 2022	1,023,274	$ 440	(2,580)	492,070	565,832	(32,488)
Balance at beginning of period (in shares) at Dec. 24, 2021		45,394
Balance at beginning of period at Dec. 24, 2021	942,621	$ 455	(2,580)	485,839	488,966	(30,059)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	233,477				233,477
Other comprehensive income (loss)	(2,429)					(2,429)
Stock-based compensation	6,128			6,128
Issuance of common stock, net of shares withheld for tax (in shares)		24
Issuance of common stock, net of shares withheld for tax	103			103
Repurchase of common stock (in shares)		(1,539)
Repurchase of common stock	(156,626)	$ (15)			(156,611)
Balance at end of period (in shares) at Mar. 25, 2022		43,879
Balance at end of period at Mar. 25, 2022	1,023,274	$ 440	(2,580)	492,070	565,832	(32,488)
Balance at beginning of period (in shares) at Sep. 30, 2022		41,351
Balance at beginning of period at Sep. 30, 2022	1,249,787	$ 415	(2,580)	500,117	801,981	(50,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	173,492				173,492
Other comprehensive income (loss)	11,324					11,324
Stock-based compensation	5,270			5,270
Issuance of common stock, net of shares withheld for tax (in shares)		200
Issuance of common stock, net of shares withheld for tax	(14,775)	$ 1		(14,776)
Repurchase of common stock (in shares)		(1,683)
Repurchase of common stock	(150,056)	$ (16)			(150,040)
Balance at end of period (in shares) at Dec. 30, 2022		39,868
Balance at end of period at Dec. 30, 2022	1,275,042	$ 400	(2,580)	490,611	825,433	(38,822)
Balance at beginning of period (in shares) at Sep. 30, 2022		41,351
Balance at beginning of period at Sep. 30, 2022	1,249,787	$ 415	(2,580)	500,117	801,981	(50,146)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	347,686
Other comprehensive income (loss)	13,987
Balance at end of period (in shares) at Mar. 31, 2023		38,938
Balance at end of period at Mar. 31, 2023	1,338,795	$ 390	(2,580)	497,810	879,334	(36,159)
Balance at beginning of period (in shares) at Dec. 30, 2022		39,868
Balance at beginning of period at Dec. 30, 2022	1,275,042	$ 400	(2,580)	490,611	825,433	(38,822)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	174,194				174,194
Other comprehensive income (loss)	2,663					2,663
Stock-based compensation	6,863			6,863
Issuance of common stock, net of shares withheld for tax (in shares)		44
Issuance of common stock, net of shares withheld for tax	336	$ 0		336
Repurchase of common stock (in shares)		(974)
Repurchase of common stock	(120,303)	$ (10)			(120,293)
Balance at end of period (in shares) at Mar. 31, 2023		38,938
Balance at end of period at Mar. 31, 2023	$ 1,338,795	$ 390	$ (2,580)	$ 497,810	$ 879,334	$ (36,159)

BASIS OF PRESENTATION AND SUMMA

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	1. BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation Organization and Ownership Structure — Atkore Inc. (the “ Company ” , “ Atkore ” or “ AI ” ) is a leading manufacturer of Electrical products primarily for the non-residential construction and renovation markets and Safety & Infrastructure solutions for the construction and industrial markets. Atkore was incorporated in the State of Delaware on November 4, 2010 under the name Atkore International Group, Inc. As of December 20, 2022, Atkore was the sole stockholder of Atkore International Holdings Inc. ( “ AIH ” ), which in turn was the sole stockholder of Atkore International Inc. ("AII"). On December 28, 2022, AIH merged into AII, with AII being the surviving entity. Accordingly, Atkore is now the sole stockholder of AII. The Electrical segment manufactures high quality products used in the construction of electrical power systems including conduit, cable, and installation accessories. This segment serves contractors, in partnership with the electrical wholesale channel. The Safety & Infrastructure segment designs and manufactures solutions including metal framing, mechanical pipe, perimeter security, and cable management for the protection and reliability of critical infrastructure. These solutions are marketed to contractors, original equipment manufacturers and end users. Basis of Presentation — The accompanying unaudited condensed consolidated financial statements of the Company included herein have been prepared in accordance with accounting principles generally accepted in the United States of America ( “ GAAP ” ). These unaudited condensed consolidated financial statements have been prepared in accordance with the Company ’ s accounting policies and on the same basis as those financial statements included in the Company ’ s latest Annual Report on Form 10-K for the year ended September 30, 2022, filed with the U.S. Securities and Exchange Commission (the “ SEC ” ) on November 18, 2022, and should be read in conjunction with those consolidated financial statements and the notes thereto. Certain information and disclosures normally included in the Company ’ s annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC. The unaudited condensed consolidated financial statements include the assets and liabilities used in operating the Company ’ s business. All intercompany balances and transactions have been eliminated in consolidation. The results of companies acquired or disposed of are included in the unaudited condensed consolidated financial statements from the effective date of acquisition or up to the date of disposal. These statements include all adjustments (consisting of normal recurring adjustments) that the Company considered necessary to present a fair statement of its results of operations, financial position and cash flows. The results reported in these unaudited condensed consolidated financial statements should not be regarded as necessarily indicative of results that may be expected for the entire year. Fiscal Periods — The Company has a fiscal year that ends on September 30. The Company ’ s fiscal quarters typically end on the last Friday in December, March and June as it follows a 4-5-4 calendar. Use of Estimates — The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclose contingent assets and liabilities at the date of the condensed consolidated financial statements and report the associated amounts of revenues and expenses. Actual results could differ materially from these estimates. Recent Accounting Pronouncements Atkore has not adopted any accounting standards in the current fiscal year. There are no accounting standards with adoption dates in the next fiscal year that are applicable to the Company.

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS	6 Months Ended
REVENUE FROM CONTRACTS WITH CUSTOMERS	Mar. 31, 2023
Revenue from Contract with Customer [Abstract]
REVENUE FROM CONTRACTS WITH CUSTOMERS	2. REVENUE FROM CONTRACTS WITH CUSTOMERS The Company’s revenue arrangements primarily consist of a single performance obligation to transfer promised goods which is satisfied at a point in time when title, risks and rewards of ownership, and subsequently control have transferred to the customer. This generally occurs when the product is shipped to the customer, with an immaterial amount of transactions in which control transfers upon delivery. The Company primarily offers assurance-type standard warranties that do not represent separate performance obligations. Under the Inflation Reduction Act of 2022 (“IRA”), the Company is eligible for tax credits related to the manufacturing and selling of components used in the solar energy industry. These tax credits are transferable under the IRA and are accounted for under a government grant accounting model. The Company has contractual arrangements with some customers who purchase these components to transfer a portion of these tax credits to those customers. Pursuant to such contractual arrangements, the Company identifies two separate performance obligations under these contracts with the first being to transfer the promised goods and the second being to transfer the defined portion of the tax credits earned. The Company allocates the total value of these transactions between the two performance obligations. As a result of this allocation, the Company recognizes a reduction to revenue, similar to a rebate. Separately, the Company recognizes the benefit of the credit generated as a reduction of cost of sales. The solar tax credit receivable is recorded in Prepaid Expenses and Other Current Assets whereas the liability to transfer the defined portion of the tax credits is recorded in Other Current Liabilities. For the six months ended March 31, 2023, the Company has recognized a reduction of revenue of $4,349 and a reduction of cost of sales of $6,010. As of March 31, 2023, the Company has a $6,209 liability for credits to be transferred and a solar tax credit receivable of $7,870. As of March 31, 2023, all activity related to the solar tax credits is within the Safety & Infrastructure segment. The Company has certain arrangements that require it to estimate at the time of sale the amounts of variable consideration that should not be recorded as revenue as certain amounts are not expected to be collected from customers, as well as an estimate of the value of products to be returned. The Company principally relies on historical experience, specific customer agreements, and anticipated future trends to estimate these amounts at the time of sale and to reduce the transaction price. These arrangements include sales discounts and allowances, volume rebates, and returned goods. The Company records its obligations related to these items within the Customer Liabilities line on the balance sheet. The Company records amounts billed to customers for reimbursement of shipping and handling costs within revenue. Shipping and handling costs associated with outbound freight after control over a product has transferred to a customer are accounted for as fulfillment costs and are included in cost of goods sold. Sales taxes and other usage-based taxes are excluded from revenue. The Company does not evaluate whether the selling price includes a financing interest component for contracts that are less than a year. The Company also expenses costs incurred to obtain a contract, primarily sales commissions, as all obligations will be settled in less than one year. The Company typically receives payment 30 to 60 days from the point it has satisfied the related performance obligation. See Note 16, “Segment Information” for revenue disaggregated by geography and product categories.

ACQUISITIONS

ACQUISITIONS	6 Months Ended
ACQUISITIONS	Mar. 31, 2023
Business Combination and Asset Acquisition [Abstract]
ACQUISITIONS	3. ACQUISITIONS From time to time, the Company enters into strategic acquisitions in an effort to better service existing customers and to obtain new customers. Fiscal 2023 On November 7, 2022, Atkore HDPE, LLC, a wholly-owned subsidiary of the Company, acquired the assets of Elite Polymer Solutions (“Elite”), for a purchase price of $90,230, of which $75,981 was paid at closing and an additional purchase price payable of $14,000 was accrued. As of the end of the second quarter of fiscal 2023, an additional $249 working capital true up payment has been made. Elite is a manufacturer of high density polyethylene (HDPE) conduit, primarily serving the telecommunications, utility, and transportation markets. As a result of the acquisition, the Company preliminarily recognized $18,604 of goodwill, $68,480 of identifiable intangible assets, of which $68,200 relates to customer relationships with an estimated useful life of 8 years, and $3,146 of working capital and other net tangible assets. As of March 31, 2023, the purchase price allocation has not been finalized as the Company is finalizing working capital, inventory, intangible assets, deferred tax assets and liabilities and fixed asset fair values. The acquisition in fiscal 2023 was funded using cash-on-hand. The Company incurred approximately $257 in acquisition-related expenses for this acquisition, which was recorded as a component of selling, general and administrative expenses. Net sales and net income of the above acquisition are included in the condensed consolidated financial statement of operations for the post-acquisition period. Due to the immaterial nature of this acquisition, the Company did not include the pro forma results of operations for this acquisition for the current period or the previous interim period. Fiscal 2022 On August 31, 2022, Atkore International Inc., and Atkore HDPE, LLC, wholly-owned subsidiaries of the Company, acquired the outstanding stock of two separate, but related, companies doing business as Cascade Poly Pipe & Conduit (“Cascade”) and Northwest Polymers, for a total purchase price of $62,100, of which $52,738 was paid at closing and an additional purchase price payable of $9,362 was accrued. As of the end of the second quarter of fiscal 2023, the Company paid $3,111 of the accrued purchase price. Cascade is a manufacturer specializing in smooth wall HDPE conduit made from recycled materials, primarily serving the telecommunications, utility and datacom markets. Northwest Polymers is a leading recycler of PVC, HDPE and other plastics and a strategic supply partner to Cascade and other manufacturers. The purchase price allocation has not been finalized as the Company is finalizing working capital, inventory, intangible assets, deferred tax assets and liabilities and fixed asset fair values. On June 22, 2022, Atkore International Inc., a wholly-owned subsidiary of the Company acquired all of the outstanding stock of United Poly Systems, LLC (“United Poly”), for a purchase price of $227,420. United Poly is a manufacturer of high density polyethylene (“HDPE”) pressure pipe and conduit, primarily serving the telecommunications, water infrastructure, renewables and energy markets. The purchase price allocation has not been finalized as the Company is finalizing working capital, inventory, intangible asset, deferred tax asset and liabilities and fixed asset fair values. On May 19, 2022, Allied Tube and Conduit Corporation, wholly-owned subsidiary of the Company acquired the assets of Talon Products, LLC (“Talon”), for a purchase price of $4,193. Included in Talon’s purchase price is a purchase price payable of $402. Talon is a manufacturer of non-metallic, injection molded cable cleats, primarily serving the power distribution markets. The Company finalized the purchase price allocation of Talon in the fourth quarter of fiscal 2022. On December 21, 2021, Atkore HDPE, LLC and Allied Tube and Conduit Corporation, wholly-owned subsidiaries of the Company, acquired the assets of Four Star Industries LLC (“Four Star”), for a purchase price of $23,195. Four Star is a manufacturer of high density polyethylene (HDPE) conduit, primarily serving the telecommunications, utility, infrastructure and datacom markets. The Company finalized the purchase price allocation of Four Star in the third quarter of fiscal 2022. On December 20, 2021, Columbia-MBF Inc., a wholly-owned subsidiary of the Company acquired all of the outstanding stock of Sasco Tubes & Roll Forming Inc. (“Sasco”), for a purchase price of $16,184, of which $13,320 was paid at closing and additional purchase price payable of $2,864 was accrued. Sasco is a Canadian manufacturer of metal framing and related products serving the electrical, mechanical, construction and solar industries. The Company finalized the purchase price allocation of Sasco in the third quarter of fiscal 2022. The acquisitions in fiscal 2022 were funded using cash-on-hand. The Company incurred approximately $3,424 in acquisition-related expenses for these acquisitions, which were recorded as a component of selling, general and administrative expenses. The purchase price was allocated to tangible and intangible assets acquired and liabilities assumed, based on their fair values. The following table summarizes the Level 3 fair values assigned to the net assets acquired and liabilities assumed as of the acquisition date for fiscal 2022: (in thousands) United Poly Other Total Fair value of consideration transferred: Cash consideration $ 227,420 $ 93,044 $ 320,464 Purchase price payable — 12,628 12,628 Working Capital Adjustment — 668 668 Total consideration transferred $ 227,420 $ 106,340 $ 333,760 Fair value of assets acquired and liabilities assumed: Cash 11,514 126 11,640 Accounts receivable 23,679 9,291 32,970 Inventories 13,455 8,111 21,566 Intangible assets 128,840 54,330 183,170 Fixed assets 13,648 8,533 22,181 Accounts payable (11,940) (5,086) (17,026) Income taxes (15,542) (2,075) (17,617) Other (1,740) 245 (1,495) Net assets acquired 161,914 73,475 235,389 Excess purchase price attributed to goodwill acquired $ 65,506 $ 32,865 $ 98,371 The Company estimates $31.1 million of the goodwill recognized by the fiscal 2022 acquisitions is deductible for tax purposes, $11.7 million that relates to United Poly and $19.4 million that relates to Cascade and Northwest Polymer. The Company estimates Goodwill recognized from the acquisitions in fiscal 2022 consists largely of the synergies and economies of scale from integrating this company with existing businesses. The following table summarizes the fair value of intangible assets as of the acquisition date: United Poly Other (in thousands) Fair Value Weighted Average Useful Life (Years) Fair Value Weighted Average Useful Life (Years) Customer relationships $ 111,700 11 $ 50,020 9 Other 17,140 8 4,310 8 Total intangible assets $ 128,840 $ 54,330 Net sales and net income of the acquired companies are included in the consolidated statement of operations for the post-acquisition period. Due to the immaterial nature of the acquisitions acquired in the first quarter of fiscal 2022, the Company did not include the pro forma results of operations for these acquisitions for the current period or the previous interim period.

POSTRETIREMENT BENEFITS

POSTRETIREMENT BENEFITS	6 Months Ended
POSTRETIREMENT BENEFITS	Mar. 31, 2023
Retirement Benefits [Abstract]
POSTRETIREMENT BENEFITS	4. POSTRETIREMENT BENEFITS The Company provides pension benefits through a number of noncontributory and contributory defined benefit retirement plans covering eligible U.S. employees. As of September 30, 2017, all defined pension benefit plans were frozen, whereby participants no longer accrue credited service. The net periodic benefit credit was as follows: Three months ended Six months ended (in thousands) Note March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Interest cost $ 1,294 $ 739 $ 2,588 $ 1,478 Expected return on plan assets (1,257) (1,348) (2,514) (2,696) Amortization of actuarial loss 167 158 333 316 Net periodic benefit cost (credit) 5 $ 204 $ (451) $ 407 $ (902)

OTHER (INCOME) AND EXPENSE, NET

OTHER (INCOME) AND EXPENSE, NET	6 Months Ended
OTHER (INCOME) AND EXPENSE, NET	Mar. 31, 2023
Other Income and Expenses [Abstract]
OTHER (INCOME) AND EXPENSE, NET	5. OTHER (INCOME) AND EXPENSE, NET Other (income) and expense, net consisted of the following: Three months ended Six months ended (in thousands) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Undesignated foreign currency derivative instruments $ — $ (634) $ — $ (810) Loss on assets held for sale 3,658 — 3,658 — Foreign exchange loss (gain) on intercompany loans (4) 278 (166) 597 Pension-related benefits 204 (451) 407 (902) Other (income) and expense, net $ 3,858 $ (807) $ 3,899 $ (1,115) The Company recognized an impairment of $3,658 on assets related to the Company’s operations in Russia. As of March 31, 2023, the Company is finalizing plans to exit its operations in Russia and expects to sell the related business at a loss, which resulted in the impairment charge taken during the quarter.

INCOME TAXES

INCOME TAXES	6 Months Ended
INCOME TAXES	Mar. 31, 2023
Income Tax Disclosure [Abstract]
INCOME TAXES	6. INCOME TAXES For the three months ended March 31, 2023 and March 25, 2022, the Company’s effective tax rate attributable to income before income taxes was 23.5% and 25.2%, respectively. For the three months ended March 31, 2023 and March 25, 2022, the Company’s income tax expense was $53,364 and $78,613 respectively. The decrease in the current period effective tax rate was driven by a decrease in state tax expense and an increase in the excess tax benefit associated with stock compensation. For the six months ended March 31, 2023 and March 25, 2022, the Company’s effective tax rate attributable to income before income taxes was 22.7% and 23.6%, respectively. For the six months ended March 31, 2023 and March 25, 2022, the Company’s income tax expense was $101,923 and $135,588 respectively. The decrease in the current period effective tax rate was driven by a decrease in state tax expense partially offset by a decrease in the excess tax benefit associated with stock compensation. A valuation allowance has been recorded against certain net operating losses in certain foreign jurisdictions. A valuation allowance is recorded when it is determined to be more likely than not that these assets will not be fully realized in the foreseeable future. The realization of deferred tax assets is dependent upon whether the Company can generate future taxable income in the appropriate character and jurisdiction to utilize the assets. The amount of the deferred tax assets considered realizable is subject to adjustment in future periods.

EARNINGS PER SHARE

EARNINGS PER SHARE	6 Months Ended
EARNINGS PER SHARE	Mar. 31, 2023
Earnings Per Share [Abstract]
EARNINGS PER SHARE	7. EARNINGS PER SHARE The Company calculates basic and diluted earnings per common share using the two-class method. Under the two-class method, net earnings are allocated to each class of common stock and participating securities as if all of the net earnings for the period had been distributed. The Company ’ s participating securities consist of share-based payment awards that contain a non-forfeitable right to receive dividends and therefore are considered to participate in undistributed earnings with common stockholders. Basic earnings per common share excludes dilution and is calculated by dividing the net earnings allocated to common stock by the weighted-average number of common stock outstanding for the period. Diluted earnings per common share is calculated by dividing net earnings allocated to common stock by the weighted-average number of shares outstanding for the period, as adjusted for the potential dilutive effect of non-participating share-based awards. The following table sets forth the computation of basic and diluted earnings per share: Three months ended Six months ended (in thousands, except per share data) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Numerator: Net income $ 174,194 $ 233,477 $ 347,686 $ 438,320 Less: Undistributed earnings allocated to participating securities 2,819 3,577 5,377 7,256 Net income available to common shareholders $ 171,375 $ 229,900 $ 342,309 $ 431,064 Denominator: Basic weighted average common shares outstanding 39,212 44,700 39,648 45,318 Effect of dilutive securities: Non-participating employee stock options (1) 537 580 534 588 Diluted weighted average common shares outstanding 39,749 45,280 40,182 45,906 Basic earnings per share $ 4.37 $ 5.14 $ 8.63 $ 9.51 Diluted earnings per share $ 4.31 $ 5.08 $ 8.52 $ 9.39 (1) Stock options to purchase shares of common stock that would have been anti-dilutive are not included in the calculation. There were no anti-dilutive options outstanding during the three months ended March 31, 2023 and March 25, 2022. Additionally, there were no anti-dilutive options outstanding during the six months ended March 31, 2023 and March 25, 2022, respectively.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE LOSS	6 Months Ended
ACCUMULATED OTHER COMPREHENSIVE LOSS	Mar. 31, 2023
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE LOSS	8. ACCUMULATED OTHER COMPREHENSIVE LOSS The following tables present the changes in accumulated other comprehensive loss by component for the three months ended March 31, 2023 and March 25, 2022. (in thousands) Defined Benefit Currency Total Balance as of December 30, 2022 $ (16,733) $ (22,089) $ (38,822) Other comprehensive loss before reclassifications — 2,462 2,462 Amounts reclassified from accumulated other 201 — 201 Net current period other comprehensive income (loss) 201 2,462 2,663 Balance as of March 31, 2023 $ (16,532) $ (19,627) $ (36,159) (in thousands) Defined Benefit Currency Total Balance as of December 24, 2021 $ (19,193) $ (10,866) $ (30,059) Other comprehensive income before reclassifications — (2,554) (2,554) Amounts reclassified from accumulated other 125 — 125 Net current period other comprehensive income 125 (2,554) (2,429) Balance as of March 25, 2022 $ (19,068) $ (13,420) $ (32,488) The following tables present the changes in accumulated other comprehensive loss by component for the six months ended March 31, 2023 and March 25, 2022. (in thousands) Defined Benefit Currency Total Balance as of September 30, 2022 $ (16,795) $ (33,351) $ (50,146) Other comprehensive loss before reclassifications — 13,724 13,724 Amounts reclassified from accumulated other 263 — 263 Net current period other comprehensive income (loss) 263 13,724 13,987 Balance as of March 31, 2023 $ (16,532) $ (19,627) $ (36,159) (in thousands) Defined Benefit Currency Total Balance as of September 30, 2021 $ (19,318) $ (9,408) $ (28,726) Other comprehensive income before reclassifications — (4,012) (4,012) Amounts reclassified from accumulated other 250 — 250 Net current period other comprehensive income 250 (4,012) (3,762) Balance as of March 25, 2022 $ (19,068) $ (13,420) $ (32,488)

INVENTORIES, NET

INVENTORIES, NET	6 Months Ended
INVENTORIES, NET	Mar. 31, 2023
Inventory Disclosure [Abstract]
INVENTORIES, NET	9. INVENTORIES, NET A majority of the Company ’ s inventories are recorded at the lower of cost (primarily last in, first out, or “ LIFO ” ) or market or net realizable value, as applicable. Approximately 81% and 82% of the Company ’ s inventories were valued at the lower of LIFO cost or market at March 31, 2023 and September 30, 2022, respectively. Interim LIFO determinations, including those at March 31, 2023, are based on management ’ s estimates of future inventory levels and costs for the remainder of the current fiscal year. (in thousands) March 31, 2023 September 30, 2022 Purchased materials and manufactured parts, net $ 144,945 $ 166,038 Work in process, net 48,966 61,182 Finished goods, net 222,139 227,291 Inventories, net $ 416,050 $ 454,511

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	6 Months Ended
PROPERTY, PLANT AND EQUIPMENT	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	10. PROPERTY, PLANT AND EQUIPMENT As of March 31, 2023, and September 30, 2022, property, plant and equipment and accumulated depreciation were as follows: (in thousands) March 31, 2023 September 30, 2022 Land $ 26,950 $ 22,113 Buildings and related improvements 176,252 172,633 Machinery and equipment 446,075 427,460 Leasehold improvements 15,067 10,512 Software 41,693 36,884 Construction in progress 145,554 99,491 Property, plant and equipment, at cost 851,591 769,093 Accumulated depreciation (408,300) (378,873) Property, plant and equipment, net $ 443,291 $ 390,220

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	6 Months Ended
GOODWILL AND INTANGIBLE ASSETS	Mar. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	11. GOODWILL AND INTANGIBLE ASSETS Changes in the carrying amount of goodwill are as follows: (in thousands) Electrical Safety & Infrastructure Total Balance as of September 30, 2022 $ 236,708 $ 52,622 $ 289,330 Goodwill acquired during year 18,604 14 18,618 Impairment (1,771) — (1,771) Exchange rate effects 4,437 72 4,509 Balance as of March 31, 2023 $ 257,978 $ 52,708 $ 310,686 Goodwill balances as of March 31, 2023 included $5,695 and $43,000 of accumulated impairment losses within the Electrical and Safety & Infrastructure segments, respectively. As described in Note 5, “Other (Income) and Expense, net”, the Company is finalizing plans to exit operations in Russia and expects to sell the related business at a loss. The Company recognized an impairment of $3,658, which includes $1,771 of impaired goodwill that was allocated from the reporting unit on a relative fair value basis. The Company assesses the recoverability of goodwill and indefinite-lived trade names on an annual basis in accordance with ASC 350, “ Intangibles - Goodwill and Other. ” The measurement date is the first day of the fourth fiscal quarter, or more frequently, if events or circumstances indicate that it is more likely than not that the fair value of a reporting unit or the respective indefinite-lived trade name is less than the carrying value. The following table provides the gross carrying value, accumulated amortization and net carrying value for each major class of intangible asset: March 31, 2023 September 30, 2022 (in thousands) Weighted Average Useful Life (Years) Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value Amortizable intangible assets: Customer relationships 11 $ 597,410 $ (291,104) $ 306,306 $ 532,768 $ (267,940) $ 264,828 Other 8 43,781 (17,988) 25,793 35,681 (10,602) 25,079 Total 641,191 (309,092) 332,099 568,449 (278,542) 289,907 Indefinite-lived intangible assets: Trade names 92,811 — 92,811 92,799 — 92,799 Total $ 734,002 $ (309,092) $ 424,910 $ 661,248 $ (278,542) $ 382,706 Other intangible assets consist of definite-lived trade names, technology, non-compete agreements and backlogs. Amortization expense for the three months ended March 31, 2023 and March 25, 2022 was $14,790 and $8,701, respectively. Amortization expense for the six months ended March 31, 2023 and March 25, 2022 was $27,586 and $16,930, respectively. Expected amortization expense for intangible assets for the remainder of fiscal 2023 and over the next five years and thereafter is as follows: (in thousands) Remaining 2023 $ 30,130 2024 54,502 2025 43,427 2026 40,825 2027 39,689 2028 29,459 Thereafter 94,067 Actual amounts of amortization may differ from estimated amounts due to additional intangible asset acquisitions, impairment of intangible assets and other events.

DEBT

DEBT	6 Months Ended
DEBT	Mar. 31, 2023
Debt Disclosure [Abstract]
DEBT	12. DEBT Debt as of March 31, 2023 and September 30, 2022 was as follows: (in thousands) March 31, 2023 September 30, 2022 Senior Secured Term Loan Facility due May 26, 2028 $ 371,524 $ 371,381 Senior Notes due June 2031 400,000 400,000 Deferred financing costs (9,912) (10,844) Long-term debt $ 761,612 $ 760,537 The asset-based credit facility (the “ ABL Credit Facility ” ) has aggregate commitments of $325,000. AII is the borrower under the ABL Credit Facility which is guaranteed by the Company and all other subsidiaries of the Company (other than AII) that are guarantors of the Senior Notes. AII ’ s availability under the ABL Credit Facility was $322,406 as of March 31, 2023 and $312,905 as of September 30, 2022. New Senior Secured Term Loan Facility - On May 26, 2021, the Company entered into a new $400.0 million senior secured term loan facility (the “New Senior Secured Term Loan Facility”). The New Senior Secured Term Loan Facility will mature on May 26, 2028 and borrowings thereunder initially bearing interest at the rate of either (x) the London Inter-Bank Offered Rate (“LIBOR”) (with a floor of 0.50%) plus 2.00%, or (y) an alternate base rate (with a floor of 1.50%) plus 1.00%. The New Senior Secured Term Loan Facility has an annual amortization rate of 1.00%. On March 15, 2023, the Company entered into an amendment to the New Senior Secured Term Loan Facility to implement a forward-looking interest rate based on the Secured Overnight Financing Rate (“SOFR”) in lieu of LIBOR, consisting of an applicable margin of 2.00% and a credit spread adjustment of (i) 0.11448% for a one-month interest period, (ii) 0.26161% for a three-month interest period and (iii) 0.42826% for a six-month interest period. ABL Credit Facility — On August 28 2020, AII amended the ABL Credit Facility (the “Amended ABL Credit Facility”). The amendment, among other things, extended the maturity of the facility to August 28, 2023, and increased the interest rate margins applicable to loans under the facility to (i) in the case of United States dollar-denominated loans, either (x) LIBOR plus an applicable margin ranging from 1.75% to 2.25%, or (y) an alternate base rate plus an applicable margin ranging from 0.75% to 1.25%, each based on available loan commitments or (ii) in the case of Canadian dollar-denominated loans, either (x) the BA rate plus an applicable margin ranging from 1.75% to 2.25% or (y) a Canadian prime rate plus an applicable margin ranging from 0.75% to 1.25%, each based on available loan commitments. The Amended ABL Credit Facility bears a commitment fee, payable quarterly in arrears, of 0.375% per annum. The Amended ABL Credit Facility also bears customary letter of credit fees. The revisions to the ABL Credit Facility were accounted for as a debt extinguishment, resulting in immediate expensing of unamortized financing costs of $273 for the year ended September 30, 2020. On May 26, 2021, the Company entered into an amendment to the Amended ABL Credit Facility. The amendment (i) extends the maturity of the facility to the earlier of five years from entering into the amendment or 91 days prior to the maturity date of the New Senior Secured Term Loan Facility if at least $100.0 million of obligations remain outstanding under the New Senior Secured Term Loan Facility on such date (ii) decreases the interest rate margins applicable to loans under the facility to (a) in the case of United States dollar-denominated loans, either (x) LIBOR plus an applicable margin ranging from 1.25% to 1.75%, or (y) an alternate base rate plus an applicable margin ranging from 0.25% to 0.75% or (b) in the case of Canadian dollar-denominated loans, either (x) the bankers acceptance rate plus an applicable margin ranging from 1.25% to 1.75% or (y) a Canadian prime rate plus an applicable margin ranging from 0.25% to 0.75%. (iii) decreases the fee payable with respect to unutilized availability under the facility from 0.375% to 0.30%, and depending on the remaining availability under the Amended ABL Credit Facility the rate may decrease to 0.25% and (iv) made certain other changes agreed upon by the lenders under the Amended ABL Credit Facility.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
FAIR VALUE MEASUREMENTS	Mar. 31, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	13. FAIR VALUE MEASUREMENTS Certain assets and liabilities are required to be recorded at fair value on a recurring basis. The Company periodically uses forward currency contracts to hedge the effects of foreign exchange relating to intercompany balances denominated in a foreign currency. These derivative instruments are not formally designated as a hedge by the Company. Short-term forward currency contracts are recorded in either other current assets or other current liabilities and long-term forward currency contracts are recorded in either other long-term assets or other long-term liabilities in the condensed consolidated balance sheet. The fair value gains and losses are included in other (income) and expense, net within the condensed consolidated statements of operations. See Note 5, “Other (Income) and Expense, net” for further detail. Cash flows associated with derivative financial instruments are recognized in the operating section of the condensed consolidated statements of cash flows. The fair value of forward currency contracts is calculated by reference to current forward exchange rates for contracts with similar maturity profiles. The Company had no active forward currency contracts or other derivative instruments as of March 31, 2023 or September 30, 2022, with the last such contract having expired in the third quarter of fiscal 2022. The following table presents the Company ’ s assets and liabilities measured at fair value: March 31, 2023 September 30, 2022 (in thousands) Level 1 Level 2 Level 1 Level 2 Assets Cash equivalents $ 260,644 $ — $ 291,757 $ — The Company ’ s remaining financial instruments consist primarily of cash, accounts receivable and accounts payable whose carrying value approximate their fair value due to their short-term nature. The estimated fair value of financial instruments not carried at fair value in the condensed consolidated balance sheets were as follows: March 31, 2023 September 30, 2022 (in thousands) Carrying Value Fair Value Carrying Value Fair Value Senior Secured Term Loan Facility due May 26, 2028 $ 373,000 $ 374,399 $ 373,000 $ 370,203 Senior Notes due June 2031 400,000 355,748 400,000 318,912 Total Debt $ 773,000 $ 730,147 $ 773,000 $ 689,115

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
COMMITMENTS AND CONTINGENCIES	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	14. COMMITMENTS AND CONTINGENCIES The Company has obligations related to commitments to purchase certain goods. As of March 31, 2023, such obligations were $243,801 for the rest of fiscal year 2023 and $10,463 for fiscal year 2024 and beyond. These amounts represent open purchase orders for materials used in production. Insurable Liabilities — The Company maintains policies with various insurance companies for its workers’ compensation, product, property, general, auto, and executive liability risks. The insurance policies that the Company maintains have various retention levels and excess coverage limits. The establishment and update of liabilities for unpaid claims, including claims incurred but not reported, is based on management's estimate as a result of the assessment by the Company's claim administrator of each claim and an independent actuarial valuation of the nature and severity of total claims. The Company utilizes a third-party claims administrator to pay claims, track and evaluate actual claims experience, and ensure consistency in the data used in the actuarial valuation. Legal Contingencies — Historically, a number of lawsuits have been filed against the Company and the Company has also received other claim demand letters alleging that the Company's anti-microbial coated steel sprinkler pipe, which the Company has not manufactured or sold for several years, is incompatible with chlorinated polyvinyl chloride and caused stress cracking in such pipe manufactured by third parties when installed together in the same sprinkler system, which the Company refers to collectively as the “Special Products Claims.” Tyco International Ltd. (“Tyco”), now Johnson Controls, Inc. (“JCI”), has a contractual obligation to indemnify the Company in respect of all remaining and future claims of incompatibility between the Company's antimicrobial coated steel sprinkler pipe and CPVC pipe used in the same sprinkler system. When Special Products Claims arise, JCI has defended and indemnified the Company as required. As of the date of this filing, no Special Product Claims are currently pending against the Company as JCI has resolved all claims at their sole cost and expense. Accordingly, at this time, the Company does not expect the outcome of the Special Products Claims proceedings, either individually or in the aggregate, to have a material adverse effect on its business, financial condition, results of operations or cash flows, and the Company believes that its reserves are adequate for all remaining contingencies for Special Products Claims and other product liabilities. In addition to the matters discussed above, from time to time, the Company is subject to a number of disputes, administrative proceedings and other claims arising out of the ordinary conduct of the Company ’ s business. These matters generally relate to disputes arising out of the use or installation of the Company ’ s products, product liability litigation, contract disputes, patent infringement accusations, employment matters, personal injury claims and similar matters. On the basis of information currently available to the Company, it does not believe that existing proceedings and claims will have a material adverse effect on its business, financial condition, results of operations or cash flows. However, litigation is unpredictable, and the Company could incur judgments or enter into settlements for current or future claims that could adversely affect its business, financial condition, results of operations or cash flows.

GUARANTEES

GUARANTEES	6 Months Ended
GUARANTEES	Mar. 31, 2023
Guarantees [Abstract]
GUARANTEES	15. GUARANTEES The Company had outstanding letters of credit totaling $2,594 supporting workers ’ compensation and general liability insurance policies as of March 31, 2023. The Company also had surety bonds primarily related to performance guarantees on supply agreements and construction contracts, and payment of duties and taxes totaling $26,394 as of March 31, 2023. In disposing of assets or businesses, the Company often provides representations, warranties and indemnities to cover various risks including unknown damage to the assets, environmental risks involved in the sale of real estate, liability to investigate and remediate environmental contamination at waste disposal sites and manufacturing facilities, and unidentified tax liabilities and legal fees related to periods prior to disposition. The Company does not have the ability to estimate the potential liability from such indemnities because they relate to unknown conditions. However, the Company has no reason to believe that these uncertainties would have a material adverse effect on the Company ’ s business, financial condition, results of operations or cash flows. In the normal course of business, the Company is liable for product performance and contract completion. In the opinion of management, such obligations will not have a material adverse effect on the Company ’ s business, financial condition, results of operations or cash flows.

SEGMENT INFORMATION

SEGMENT INFORMATION	6 Months Ended
SEGMENT INFORMATION	Mar. 31, 2023
Segment Reporting [Abstract]
SEGMENT INFORMATION	16. SEGMENT INFORMATION The Electrical segment manufactures high quality products used in the construction of electrical power systems including conduit, cable and installation accessories. This segment serves contractors in partnership with the electrical wholesale channel. The Safety & Infrastructure segment designs and manufactures solutions including metal framing, mechanical pipe, perimeter security and cable management for the protection and reliability of critical infrastructure. These solutions are marketed to contractors, original equipment manufacturers and end users. Both segments use Adjusted EBITDA as the primary measure of profit and loss. Segment Adjusted EBITDA is income (loss) before income taxes, adjusted to exclude unallocated expenses, depreciation and amortization, interest expense, net, stock-based compensation, loss on extinguishment of debt, certain legal matters, and other items, such as inventory reserves and adjustments, (gain) loss on disposal of property, plant and equipment, insurance recovery related to damages of property, plant and equipment, release of indemnified uncertain tax positions, realized or unrealized gain (loss) on foreign currency impacts of intercompany loans and related forward currency derivatives, gain on purchase of business, loss on assets held for sale, restructuring costs and transaction costs. Intersegment transactions primarily consist of product sales at designated transfer prices on an arm ’ s-length basis. Gross profit earned and reported within the segment is eliminated in the Company ’ s consolidated results. Certain manufacturing and distribution expenses are allocated between the segments on a pro rata basis due to the shared nature of activities. Recorded amounts represent a proportional amount of the quantity of product produced for each segment. Certain assets, such as machinery and equipment and facilities, are not allocated to each segment despite serving both segments. These shared assets are reported within the Safety & Infrastructure segment. The Company allocates certain corporate operating expenses that directly benefit our operating segments, such as insurance and information technology, on a basis that reasonably approximates an estimate of the use of these services. Three months ended March 31, 2023 March 25, 2022 (in thousands) External Net Sales Intersegment Sales Adjusted EBITDA External Net Sales Intersegment Sales Adjusted EBITDA Electrical $ 680,955 $ 10 $ 256,883 $ 758,347 $ 1,530 $ 330,970 Safety & Infrastructure 214,979 75 33,194 224,226 59 28,917 Eliminations — (85) — (1,589) Consolidated operations $ 895,934 $ — $ 982,573 $ — Six months ended March 31, 2023 March 25, 2022 (in thousands) External Net Sales Intersegment Sales Adjusted EBITDA External Net Sales Intersegment Sales Adjusted EBITDA Electrical $ 1,319,660 $ 10 $ 500,720 $ 1,398,691 $ 2,869 $ 610,517 Safety & Infrastructure 410,095 218 66,597 424,683 112 56,349 Eliminations — (228) — (2,981) Consolidated operations $ 1,729,755 $ — $ 1,823,374 $ — Presented below is a reconciliation of operating Segment Adjusted EBITDA to Income before income taxes: Three months ended Six months ended (in thousands) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Operating segment Adjusted EBITDA Electrical $ 256,883 $ 330,970 $ 500,720 $ 610,517 Safety & Infrastructure 33,194 28,917 66,597 56,349 Total $ 290,077 $ 359,887 $ 567,317 $ 666,866 Unallocated expenses (a) (14,036) (13,721) (27,431) (27,690) Depreciation and amortization (28,598) (19,994) (54,566) (40,040) Interest expense, net (8,475) (7,514) (17,963) (14,432) Stock-based compensation (6,863) (6,128) (12,133) (9,555) Other (b) (4,547) (440) (5,615) (1,241) Income before income taxes $ 227,558 $ 312,090 $ 449,609 $ 573,908 (a) Represents unallocated selling, general and administrative activities and associated expenses including, in part, executive, legal, finance, human resources, information technology, business development and communications, as well as certain costs and earnings of employee-related benefits plans, such as stock-based compensation and a portion of self-insured medical costs. (b) Represents other items, such as inventory reserves and adjustments, loss on disposal of property, plant and equipment, release of indemnified uncertain tax positions, gain on purchase of business. loss on assets held for sale, realized or unrealized gain (loss) on foreign currency impacts of intercompany loans and related forward currency derivatives, and restructuring charges. The Company ’ s net sales by geography were as follows for the three months ended and the six months ended March 31, 2023 and March 25, 2022: Three months ended Six months ended (in thousands) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 United States $ 799,562 $ 895,585 $ 1,549,649 $ 1,652,983 Other Americas 23,063 24,649 43,617 47,136 Europe 61,789 52,709 113,819 103,162 Asia-Pacific 11,520 9,630 22,670 20,093 Total $ 895,934 $ 982,573 $ 1,729,755 $ 1,823,374 The table below shows the amount of net sales from external customers for each of the Company ’ s product categories which accounted for 10% or more of consolidated net sales in either period for the three months ended and the six months ended March 31, 2023 and March 25, 2022: Three months ended Six months ended (in thousands) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Metal Electrical Conduit and Fittings $ 128,322 $ 153,049 $ 239,480 $ 302,925 Electrical Cable & Flexible Conduit 129,785 137,244 253,511 252,939 Plastic Pipe and Conduit 323,139 374,775 639,304 663,764 Other Electrical products 99,709 93,279 187,365 179,063 Electrical 680,955 758,347 1,319,660 1,398,691 Mechanical Pipe 98,727 112,818 177,501 224,061 Other Safety & Infrastructure products 116,252 111,408 232,594 200,622 Safety & Infrastructure 214,979 224,226 410,095 424,683 Net sales $ 895,934 $ 982,573 $ 1,729,755 $ 1,823,374

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	6 Months Ended
SUBSEQUENT EVENTS	Mar. 31, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	17. SUBSEQUENT EVENTS Subsequent to quarter end, the Company has repurchased 0.8 million shares at a cost of $102.5 million as of May 9, 2023.

BASIS OF PRESENTATION AND SUM_2

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation — The accompanying unaudited condensed consolidated financial statements of the Company included herein have been prepared in accordance with accounting principles generally accepted in the United States of America ( “ GAAP ” ). These unaudited condensed consolidated financial statements have been prepared in accordance with the Company ’ s accounting policies and on the same basis as those financial statements included in the Company ’ s latest Annual Report on Form 10-K for the year ended September 30, 2022, filed with the U.S. Securities and Exchange Commission (the “ SEC ” ) on November 18, 2022, and should be read in conjunction with those consolidated financial statements and the notes thereto. Certain information and disclosures normally included in the Company ’ s annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC. The unaudited condensed consolidated financial statements include the assets and liabilities used in operating the Company ’ s business. All intercompany balances and transactions have been eliminated in consolidation. The results of companies acquired or disposed of are included in the unaudited condensed consolidated financial statements from the effective date of acquisition or up to the date of disposal. These statements include all adjustments (consisting of normal recurring adjustments) that the Company considered necessary to present a fair statement of its results of operations, financial position and cash flows. The results reported in these unaudited condensed consolidated financial statements should not be regarded as necessarily indicative of results that may be expected for the entire year.
Fiscal Periods	Fiscal Periods — The Company has a fiscal year that ends on September 30. The Company ’ s fiscal quarters typically end on the last Friday in December, March and June as it follows a 4-5-4 calendar.
Use of Estimates	Use of Estimates — The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclose contingent assets and liabilities at the date of the condensed consolidated financial statements and report the associated amounts of revenues and expenses. Actual results could differ materially from these estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Atkore has not adopted any accounting standards in the current fiscal year. There are no accounting standards with adoption dates in the next fiscal year that are applicable to the Company.

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	6 Months Ended
ACQUISITIONS (Tables)	Mar. 31, 2023
Business Combination and Asset Acquisition [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the Level 3 fair values assigned to the net assets acquired and liabilities assumed as of the acquisition date for fiscal 2022: (in thousands) United Poly Other Total Fair value of consideration transferred: Cash consideration $ 227,420 $ 93,044 $ 320,464 Purchase price payable — 12,628 12,628 Working Capital Adjustment — 668 668 Total consideration transferred $ 227,420 $ 106,340 $ 333,760 Fair value of assets acquired and liabilities assumed: Cash 11,514 126 11,640 Accounts receivable 23,679 9,291 32,970 Inventories 13,455 8,111 21,566 Intangible assets 128,840 54,330 183,170 Fixed assets 13,648 8,533 22,181 Accounts payable (11,940) (5,086) (17,026) Income taxes (15,542) (2,075) (17,617) Other (1,740) 245 (1,495) Net assets acquired 161,914 73,475 235,389 Excess purchase price attributed to goodwill acquired $ 65,506 $ 32,865 $ 98,371
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The following table summarizes the fair value of intangible assets as of the acquisition date: United Poly Other (in thousands) Fair Value Weighted Average Useful Life (Years) Fair Value Weighted Average Useful Life (Years) Customer relationships $ 111,700 11 $ 50,020 9 Other 17,140 8 4,310 8 Total intangible assets $ 128,840 $ 54,330

POSTRETIREMENT BENEFITS (Tables

POSTRETIREMENT BENEFITS (Tables)	6 Months Ended
POSTRETIREMENT BENEFITS (Tables)	Mar. 31, 2023
Retirement Benefits [Abstract]
Schedule of Net Periodic Benefit Cost	The net periodic benefit credit was as follows: Three months ended Six months ended (in thousands) Note March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Interest cost $ 1,294 $ 739 $ 2,588 $ 1,478 Expected return on plan assets (1,257) (1,348) (2,514) (2,696) Amortization of actuarial loss 167 158 333 316 Net periodic benefit cost (credit) 5 $ 204 $ (451) $ 407 $ (902)

OTHER (INCOME) AND EXPENSE, N_2

OTHER (INCOME) AND EXPENSE, NET (Tables)	6 Months Ended
OTHER (INCOME) AND EXPENSE, NET (Tables)	Mar. 31, 2023
Other Income and Expenses [Abstract]
Schedule of Other (Income) and Expense, Net	Other (income) and expense, net consisted of the following: Three months ended Six months ended (in thousands) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Undesignated foreign currency derivative instruments $ — $ (634) $ — $ (810) Loss on assets held for sale 3,658 — 3,658 — Foreign exchange loss (gain) on intercompany loans (4) 278 (166) 597 Pension-related benefits 204 (451) 407 (902) Other (income) and expense, net $ 3,858 $ (807) $ 3,899 $ (1,115) The Company recognized an impairment of $3,658 on assets related to the Company’s operations in Russia. As of March 31, 2023, the Company is finalizing plans to exit its operations in Russia and expects to sell the related business at a loss, which resulted in the impairment charge taken during the quarter.

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	6 Months Ended
EARNINGS PER SHARE (Tables)	Mar. 31, 2023
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Income Per Share	The following table sets forth the computation of basic and diluted earnings per share: Three months ended Six months ended (in thousands, except per share data) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Numerator: Net income $ 174,194 $ 233,477 $ 347,686 $ 438,320 Less: Undistributed earnings allocated to participating securities 2,819 3,577 5,377 7,256 Net income available to common shareholders $ 171,375 $ 229,900 $ 342,309 $ 431,064 Denominator: Basic weighted average common shares outstanding 39,212 44,700 39,648 45,318 Effect of dilutive securities: Non-participating employee stock options (1) 537 580 534 588 Diluted weighted average common shares outstanding 39,749 45,280 40,182 45,906 Basic earnings per share $ 4.37 $ 5.14 $ 8.63 $ 9.51 Diluted earnings per share $ 4.31 $ 5.08 $ 8.52 $ 9.39 (1) Stock options to purchase shares of common stock that would have been anti-dilutive are not included in the calculation. There were no anti-dilutive options outstanding during the three months ended March 31, 2023 and March 25, 2022. Additionally, there were no anti-dilutive options outstanding during the six months ended March 31, 2023 and March 25, 2022, respectively.

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	6 Months Ended
ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	Mar. 31, 2023
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Loss	The following tables present the changes in accumulated other comprehensive loss by component for the three months ended March 31, 2023 and March 25, 2022. (in thousands) Defined Benefit Currency Total Balance as of December 30, 2022 $ (16,733) $ (22,089) $ (38,822) Other comprehensive loss before reclassifications — 2,462 2,462 Amounts reclassified from accumulated other 201 — 201 Net current period other comprehensive income (loss) 201 2,462 2,663 Balance as of March 31, 2023 $ (16,532) $ (19,627) $ (36,159) (in thousands) Defined Benefit Currency Total Balance as of December 24, 2021 $ (19,193) $ (10,866) $ (30,059) Other comprehensive income before reclassifications — (2,554) (2,554) Amounts reclassified from accumulated other 125 — 125 Net current period other comprehensive income 125 (2,554) (2,429) Balance as of March 25, 2022 $ (19,068) $ (13,420) $ (32,488) The following tables present the changes in accumulated other comprehensive loss by component for the six months ended March 31, 2023 and March 25, 2022. (in thousands) Defined Benefit Currency Total Balance as of September 30, 2022 $ (16,795) $ (33,351) $ (50,146) Other comprehensive loss before reclassifications — 13,724 13,724 Amounts reclassified from accumulated other 263 — 263 Net current period other comprehensive income (loss) 263 13,724 13,987 Balance as of March 31, 2023 $ (16,532) $ (19,627) $ (36,159) (in thousands) Defined Benefit Currency Total Balance as of September 30, 2021 $ (19,318) $ (9,408) $ (28,726) Other comprehensive income before reclassifications — (4,012) (4,012) Amounts reclassified from accumulated other 250 — 250 Net current period other comprehensive income 250 (4,012) (3,762) Balance as of March 25, 2022 $ (19,068) $ (13,420) $ (32,488)

INVENTORIES, NET (Tables)

INVENTORIES, NET (Tables)	6 Months Ended
INVENTORIES, NET (Tables)	Mar. 31, 2023
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	(in thousands) March 31, 2023 September 30, 2022 Purchased materials and manufactured parts, net $ 144,945 $ 166,038 Work in process, net 48,966 61,182 Finished goods, net 222,139 227,291 Inventories, net $ 416,050 $ 454,511

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	6 Months Ended
PROPERTY, PLANT AND EQUIPMENT (Tables)	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	As of March 31, 2023, and September 30, 2022, property, plant and equipment and accumulated depreciation were as follows: (in thousands) March 31, 2023 September 30, 2022 Land $ 26,950 $ 22,113 Buildings and related improvements 176,252 172,633 Machinery and equipment 446,075 427,460 Leasehold improvements 15,067 10,512 Software 41,693 36,884 Construction in progress 145,554 99,491 Property, plant and equipment, at cost 851,591 769,093 Accumulated depreciation (408,300) (378,873) Property, plant and equipment, net $ 443,291 $ 390,220

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	6 Months Ended
GOODWILL AND INTANGIBLE ASSETS (Tables)	Mar. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Changes in the carrying amount of goodwill are as follows: (in thousands) Electrical Safety & Infrastructure Total Balance as of September 30, 2022 $ 236,708 $ 52,622 $ 289,330 Goodwill acquired during year 18,604 14 18,618 Impairment (1,771) — (1,771) Exchange rate effects 4,437 72 4,509 Balance as of March 31, 2023 $ 257,978 $ 52,708 $ 310,686
Schedule of Finite-Lived Intangible Assets	The following table provides the gross carrying value, accumulated amortization and net carrying value for each major class of intangible asset: March 31, 2023 September 30, 2022 (in thousands) Weighted Average Useful Life (Years) Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value Amortizable intangible assets: Customer relationships 11 $ 597,410 $ (291,104) $ 306,306 $ 532,768 $ (267,940) $ 264,828 Other 8 43,781 (17,988) 25,793 35,681 (10,602) 25,079 Total 641,191 (309,092) 332,099 568,449 (278,542) 289,907 Indefinite-lived intangible assets: Trade names 92,811 — 92,811 92,799 — 92,799 Total $ 734,002 $ (309,092) $ 424,910 $ 661,248 $ (278,542) $ 382,706
Schedule of Indefinite-Lived Intangible Assets	The following table provides the gross carrying value, accumulated amortization and net carrying value for each major class of intangible asset: March 31, 2023 September 30, 2022 (in thousands) Weighted Average Useful Life (Years) Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value Amortizable intangible assets: Customer relationships 11 $ 597,410 $ (291,104) $ 306,306 $ 532,768 $ (267,940) $ 264,828 Other 8 43,781 (17,988) 25,793 35,681 (10,602) 25,079 Total 641,191 (309,092) 332,099 568,449 (278,542) 289,907 Indefinite-lived intangible assets: Trade names 92,811 — 92,811 92,799 — 92,799 Total $ 734,002 $ (309,092) $ 424,910 $ 661,248 $ (278,542) $ 382,706
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Expected amortization expense for intangible assets for the remainder of fiscal 2023 and over the next five years and thereafter is as follows: (in thousands) Remaining 2023 $ 30,130 2024 54,502 2025 43,427 2026 40,825 2027 39,689 2028 29,459 Thereafter 94,067

DEBT (Tables)

DEBT (Tables)	6 Months Ended
DEBT (Tables)	Mar. 31, 2023
Debt Disclosure [Abstract]
Schedule of Debt	Debt as of March 31, 2023 and September 30, 2022 was as follows: (in thousands) March 31, 2023 September 30, 2022 Senior Secured Term Loan Facility due May 26, 2028 $ 371,524 $ 371,381 Senior Notes due June 2031 400,000 400,000 Deferred financing costs (9,912) (10,844) Long-term debt $ 761,612 $ 760,537

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
FAIR VALUE MEASUREMENTS (Tables)	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value	The following table presents the Company ’ s assets and liabilities measured at fair value: March 31, 2023 September 30, 2022 (in thousands) Level 1 Level 2 Level 1 Level 2 Assets Cash equivalents $ 260,644 $ — $ 291,757 $ —
Schedule of Estimated Fair Value of Financial Instruments Not Carried at Fair Value	The estimated fair value of financial instruments not carried at fair value in the condensed consolidated balance sheets were as follows: March 31, 2023 September 30, 2022 (in thousands) Carrying Value Fair Value Carrying Value Fair Value Senior Secured Term Loan Facility due May 26, 2028 $ 373,000 $ 374,399 $ 373,000 $ 370,203 Senior Notes due June 2031 400,000 355,748 400,000 318,912 Total Debt $ 773,000 $ 730,147 $ 773,000 $ 689,115

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	6 Months Ended
SEGMENT INFORMATION (Tables)	Mar. 31, 2023
Segment Reporting [Abstract]
Schedule of Segment Information	Three months ended March 31, 2023 March 25, 2022 (in thousands) External Net Sales Intersegment Sales Adjusted EBITDA External Net Sales Intersegment Sales Adjusted EBITDA Electrical $ 680,955 $ 10 $ 256,883 $ 758,347 $ 1,530 $ 330,970 Safety & Infrastructure 214,979 75 33,194 224,226 59 28,917 Eliminations — (85) — (1,589) Consolidated operations $ 895,934 $ — $ 982,573 $ — Six months ended March 31, 2023 March 25, 2022 (in thousands) External Net Sales Intersegment Sales Adjusted EBITDA External Net Sales Intersegment Sales Adjusted EBITDA Electrical $ 1,319,660 $ 10 $ 500,720 $ 1,398,691 $ 2,869 $ 610,517 Safety & Infrastructure 410,095 218 66,597 424,683 112 56,349 Eliminations — (228) — (2,981) Consolidated operations $ 1,729,755 $ — $ 1,823,374 $ — Presented below is a reconciliation of operating Segment Adjusted EBITDA to Income before income taxes: Three months ended Six months ended (in thousands) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Operating segment Adjusted EBITDA Electrical $ 256,883 $ 330,970 $ 500,720 $ 610,517 Safety & Infrastructure 33,194 28,917 66,597 56,349 Total $ 290,077 $ 359,887 $ 567,317 $ 666,866 Unallocated expenses (a) (14,036) (13,721) (27,431) (27,690) Depreciation and amortization (28,598) (19,994) (54,566) (40,040) Interest expense, net (8,475) (7,514) (17,963) (14,432) Stock-based compensation (6,863) (6,128) (12,133) (9,555) Other (b) (4,547) (440) (5,615) (1,241) Income before income taxes $ 227,558 $ 312,090 $ 449,609 $ 573,908 (a) Represents unallocated selling, general and administrative activities and associated expenses including, in part, executive, legal, finance, human resources, information technology, business development and communications, as well as certain costs and earnings of employee-related benefits plans, such as stock-based compensation and a portion of self-insured medical costs. (b) Represents other items, such as inventory reserves and adjustments, loss on disposal of property, plant and equipment, release of indemnified uncertain tax positions, gain on purchase of business. loss on assets held for sale, realized or unrealized gain (loss) on foreign currency impacts of intercompany loans and related forward currency derivatives, and restructuring charges. The Company ’ s net sales by geography were as follows for the three months ended and the six months ended March 31, 2023 and March 25, 2022: Three months ended Six months ended (in thousands) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 United States $ 799,562 $ 895,585 $ 1,549,649 $ 1,652,983 Other Americas 23,063 24,649 43,617 47,136 Europe 61,789 52,709 113,819 103,162 Asia-Pacific 11,520 9,630 22,670 20,093 Total $ 895,934 $ 982,573 $ 1,729,755 $ 1,823,374 The table below shows the amount of net sales from external customers for each of the Company ’ s product categories which accounted for 10% or more of consolidated net sales in either period for the three months ended and the six months ended March 31, 2023 and March 25, 2022: Three months ended Six months ended (in thousands) March 31, 2023 March 25, 2022 March 31, 2023 March 25, 2022 Metal Electrical Conduit and Fittings $ 128,322 $ 153,049 $ 239,480 $ 302,925 Electrical Cable & Flexible Conduit 129,785 137,244 253,511 252,939 Plastic Pipe and Conduit 323,139 374,775 639,304 663,764 Other Electrical products 99,709 93,279 187,365 179,063 Electrical 680,955 758,347 1,319,660 1,398,691 Mechanical Pipe 98,727 112,818 177,501 224,061 Other Safety & Infrastructure products 116,252 111,408 232,594 200,622 Safety & Infrastructure 214,979 224,226 410,095 424,683 Net sales $ 895,934 $ 982,573 $ 1,729,755 $ 1,823,374

REVENUE FROM CONTRACTS WITH C_2

REVENUE FROM CONTRACTS WITH CUSTOMERS (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2023 USD ($) performanceObligation	Mar. 31, 2023 USD ($) performanceObligation
Revenue from Contract with Customer [Abstract]
Reduction of revenue	$ 4,349	$ 4,349
Reduction of cost of sales	6,010	6,010
Liability for credits to be transferred	6,209	6,209
Benefit receivable	$ 7,870	$ 7,870
Disaggregation of Revenue [Line Items]
Number of performance obligations \| performanceObligation	2	2
Minimum
Disaggregation of Revenue [Line Items]
Period of payment received from related performance obligation satisfied		30 days
Maximum
Disaggregation of Revenue [Line Items]
Period of payment received from related performance obligation satisfied		60 days
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-04-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year	1 year

ACQUISITIONS - Narrative (Detai

ACQUISITIONS - Narrative (Details) $ in Thousands							3 Months Ended	6 Months Ended	12 Months Ended
ACQUISITIONS - Narrative (Details) $ in Thousands	Nov. 07, 2022 USD ($)	Aug. 31, 2022 USD ($) acquiree	Jun. 22, 2022 USD ($)	May 19, 2022 USD ($)	Dec. 21, 2021 USD ($)	Dec. 20, 2021 USD ($)	Mar. 31, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)
Business Acquisition [Line Items]
Working capital true up payment			$ 668
Goodwill							$ 310,686	$ 310,686	$ 289,330
Business acquisition, goodwill deductible for tax purposes									31,100
Selling, General and Administrative Expenses
Business Acquisition [Line Items]
Business acquisition-related expenses								$ 257	3,424
Elite Polymer Solutions
Business Acquisition [Line Items]
Purchase price of business acquisition	$ 90,230
Payments to acquire business	75,981
Purchase price payable	14,000
Working capital true up payment							249
Goodwill	18,604
Identifiable intangible assets acquired	68,480
Working capital and other net tangible assets acquired	3,146
Elite Polymer Solutions \| Customer relationships
Business Acquisition [Line Items]
Identifiable intangible assets acquired	$ 68,200
Weighted Average Useful Life (Years)	8 years
Cascade and Northwest Polymers
Business Acquisition [Line Items]
Purchase price of business acquisition		$ 62,100
Payments to acquire business		52,738					$ 3,111
Purchase price payable		$ 9,362
Business combination, number of acquiree \| acquiree		2
Business acquisition, goodwill deductible for tax purposes									19,400
United Poly
Business Acquisition [Line Items]
Purchase price of business acquisition			227,420
Payments to acquire business			227,420
Purchase price payable			0
Working capital true up payment			0
Goodwill			$ 65,506
Business acquisition, goodwill deductible for tax purposes									$ 11,700
United Poly \| Customer relationships
Business Acquisition [Line Items]
Weighted Average Useful Life (Years)			11 years
Talon
Business Acquisition [Line Items]
Purchase price of business acquisition				$ 4,193
Purchase price payable				$ 402
Four Star
Business Acquisition [Line Items]
Purchase price of business acquisition					$ 23,195
Sasco
Business Acquisition [Line Items]
Purchase price of business acquisition						$ 16,184
Payments to acquire business						13,320
Purchase price payable						$ 2,864

ACQUISITIONS - Summary of Level

ACQUISITIONS - Summary of Level 3 Fair Values Assigned to Net Assets Acquired and Liabilities Assumed As of Acquisition Date (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 22, 2022	Sep. 30, 2022	Mar. 31, 2023
Fair value of consideration transferred:
Working Capital Adjustment	$ 668
Fair value of assets acquired and liabilities assumed:
Excess purchase price attributed to goodwill acquired		$ 289,330	$ 310,686
Fiscal 2022 Acquisitions
Fair value of consideration transferred:
Cash consideration		320,464
Purchase price payable		12,628
Total consideration transferred		333,760
Fair value of assets acquired and liabilities assumed:
Cash		11,640
Accounts receivable		32,970
Inventories		21,566
Intangible assets		183,170
Fixed assets		22,181
Accounts payable		(17,026)
Income taxes		(17,617)
Other		(1,495)
Net assets acquired		235,389
Excess purchase price attributed to goodwill acquired		98,371
United Poly
Fair value of consideration transferred:
Cash consideration	227,420
Purchase price payable	0
Working Capital Adjustment	0
Total consideration transferred	227,420
Fair value of assets acquired and liabilities assumed:
Cash	11,514
Accounts receivable	23,679
Inventories	13,455
Intangible assets	128,840
Fixed assets	13,648
Accounts payable	(11,940)
Income taxes	(15,542)
Other	(1,740)
Net assets acquired	161,914
Excess purchase price attributed to goodwill acquired	65,506
Other
Fair value of consideration transferred:
Cash consideration		93,044
Purchase price payable		12,628
Working Capital Adjustment	668
Total consideration transferred		106,340
Fair value of assets acquired and liabilities assumed:
Cash		126
Accounts receivable		9,291
Inventories		8,111
Intangible assets	$ 54,330	54,330
Fixed assets		8,533
Accounts payable		(5,086)
Income taxes		(2,075)
Other		245
Net assets acquired		73,475
Excess purchase price attributed to goodwill acquired		$ 32,865

ACQUISITIONS - Summary of Fair

ACQUISITIONS - Summary of Fair Value as of Acquisition Date (Details) - USD ($) $ in Thousands	Jun. 22, 2022	Sep. 30, 2022
United Poly
Business Acquisition [Line Items]
Fair Value	$ 128,840
United Poly \| Customer relationships
Business Acquisition [Line Items]
Fair Value	$ 111,700
Weighted Average Useful Life (Years)	11 years
United Poly \| Other
Business Acquisition [Line Items]
Fair Value	$ 17,140
Weighted Average Useful Life (Years)	8 years
Other
Business Acquisition [Line Items]
Fair Value	$ 54,330	$ 54,330
Other \| Customer relationships
Business Acquisition [Line Items]
Fair Value	$ 50,020
Weighted Average Useful Life (Years)	9 years
Other \| Other
Business Acquisition [Line Items]
Fair Value	$ 4,310
Weighted Average Useful Life (Years)	8 years

POSTRETIREMENT BENEFITS - Net P

POSTRETIREMENT BENEFITS - Net Periodic Benefit Cost (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,294	$ 739	$ 2,588	$ 1,478
Expected return on plan assets	(1,257)	(1,348)	(2,514)	(2,696)
Amortization of actuarial loss	167	158	333	316
Net periodic benefit cost (credit)	$ 204	$ (451)	$ 407	$ (902)

OTHER (INCOME) AND EXPENSE, N_3

OTHER (INCOME) AND EXPENSE, NET (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Other Income and Expenses [Abstract]
Undesignated foreign currency derivative instruments	$ 0	$ (634)	$ 0	$ (810)
Loss on assets held for sale	3,658	0	3,658	0
Foreign exchange loss (gain) on intercompany loans	(4)	278	(166)	597
Pension-related benefits	204	(451)	407	(902)
Other (income) and expense, net	$ 3,858	$ (807)	$ 3,899	$ (1,115)

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
INCOME TAXES (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Income Tax Disclosure [Abstract]
Effective income tax rate	23.50%	25.20%	22.70%	23.60%
Income tax expense	$ 53,364	$ 78,613	$ 101,923	$ 135,588

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023	Dec. 30, 2022	Mar. 25, 2022	Dec. 24, 2021	Mar. 31, 2023	Mar. 25, 2022
Numerator:
Net income	$ 174,194	$ 173,492	$ 233,477	$ 204,843	$ 347,686	$ 438,320
Less: Undistributed earnings allocated to participating securities	2,819		3,577		5,377	7,256
Net income available to common shareholders	171,375		229,900		342,309	431,064
Net income available to common shareholders	$ 171,375		$ 229,900		$ 342,309	$ 431,064
Denominator:
Basic weighted average common shares outstanding (in shares)	39,212		44,700		39,648	45,318
Effect of dilutive securities: Non-participating employee stock options (in shares)	537		580		534	588
Diluted weighted average common shares outstanding (in shares)	39,749		45,280		40,182	45,906
Basic earnings per share (in dollars per share)	$ 4.37		$ 5.14		$ 8.63	$ 9.51
Diluted earnings per share (in dollars per share)	$ 4.31		$ 5.08		$ 8.52	$ 9.39
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	0		0		0	0

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023	Dec. 30, 2022	Mar. 25, 2022	Dec. 24, 2021	Mar. 31, 2023	Mar. 25, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,275,042	$ 1,249,787	$ 942,621	$ 864,736	$ 1,249,787	$ 864,736
Other comprehensive income (loss) before reclassifications	2,462		(2,554)		13,724	(4,012)
Amounts reclassified from accumulated other comprehensive income, net of tax	201		125		263	250
Total other comprehensive (loss) income	2,663	11,324	(2,429)	(1,333)	13,987	(3,762)
Balance at end of period	1,338,795	1,275,042	1,023,274	942,621	1,338,795	1,023,274
Defined Benefit Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(16,733)	(16,795)	(19,193)	(19,318)	(16,795)	(19,318)
Other comprehensive income (loss) before reclassifications	0		0		0	0
Amounts reclassified from accumulated other comprehensive income, net of tax	201		125		263	250
Total other comprehensive (loss) income	201		125		263	250
Balance at end of period	(16,532)	(16,733)	(19,068)	(19,193)	(16,532)	(19,068)
Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(22,089)	(33,351)	(10,866)	(9,408)	(33,351)	(9,408)
Other comprehensive income (loss) before reclassifications	2,462		(2,554)		13,724	(4,012)
Amounts reclassified from accumulated other comprehensive income, net of tax	0		0		0	0
Total other comprehensive (loss) income	2,462		(2,554)		13,724	(4,012)
Balance at end of period	(19,627)	(22,089)	(13,420)	(10,866)	(19,627)	(13,420)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(38,822)	(50,146)	(30,059)	(28,726)	(50,146)	(28,726)
Total other comprehensive (loss) income	2,663	11,324	(2,429)	(1,333)
Balance at end of period	$ (36,159)	$ (38,822)	$ (32,488)	$ (30,059)	$ (36,159)	$ (32,488)

INVENTORIES, NET - Narrative (D

INVENTORIES, NET - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Inventory Disclosure [Abstract]
Inventories at lower of LIFO cost or market	81%	82%
FIFO inventory, higher than reported	$ 20,883	$ 64,550
Excess and obsolete inventory reserve	$ 21,070	$ 18,996

INVENTORIES, NET - Schedule of

INVENTORIES, NET - Schedule of Company Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Inventory Disclosure [Abstract]
Purchased materials and manufactured parts, net	$ 144,945	$ 166,038
Work in process, net	48,966	61,182
Finished goods, net	222,139	227,291
Inventories, net	$ 416,050	$ 454,511

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 851,591	$ 769,093
Accumulated depreciation	(408,300)	(378,873)
Property, plant and equipment, net	443,291	390,220
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	26,950	22,113
Buildings and related improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	176,252	172,633
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	446,075	427,460
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	15,067	10,512
Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	41,693	36,884
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 145,554	$ 99,491

PROPERTY, PLANT AND EQUIPMENT -

PROPERTY, PLANT AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 13,808	$ 11,293	$ 26,980	$ 23,110

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Goodwill (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2023 USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 289,330
Goodwill acquired during year	18,618
Impairment	(1,771)
Exchange rate effects	4,509
Balance at end of period	310,686
Electrical
Goodwill [Roll Forward]
Balance at beginning of period	236,708
Goodwill acquired during year	18,604
Impairment	(1,771)
Exchange rate effects	4,437
Balance at end of period	257,978
Safety & Infrastructure
Goodwill [Roll Forward]
Balance at beginning of period	52,622
Goodwill acquired during year	14
Impairment	0
Exchange rate effects	72
Balance at end of period	$ 52,708

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Goodwill [Line Items]
Loss on assets held for sale	$ 3,658	$ 0	$ 3,658	$ 0
Impairment			(1,771)
Intangible asset amortization	14,790	$ 8,701	27,586	$ 16,930
Electrical
Goodwill [Line Items]
Accumulated impairment loss	5,695		5,695
Impairment			(1,771)
Safety & Infrastructure
Goodwill [Line Items]
Accumulated impairment loss	$ 43,000		43,000
Impairment			$ 0

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS - Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2023	Sep. 30, 2022
Amortizable intangible assets:
Gross Carrying Value	$ 641,191	$ 568,449
Accumulated Amortization	(309,092)	(278,542)
Net Carrying Value	332,099	289,907
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Value	734,002	661,248
Net Carrying Value	424,910	382,706
Trade names
Indefinite-lived Intangible Assets [Line Items]
Gross carrying value/net carrying value	92,811	92,799
Customer relationships
Amortizable intangible assets:
Gross Carrying Value	597,410	532,768
Accumulated Amortization	(291,104)	(267,940)
Net Carrying Value	$ 306,306	264,828
Customer relationships \| Weighted Average Useful Life (Years)
Amortizable intangible assets:
Weighted Average Useful Life (Years)	11 years
Other
Amortizable intangible assets:
Gross Carrying Value	$ 43,781	35,681
Accumulated Amortization	(17,988)	(10,602)
Net Carrying Value	$ 25,793	$ 25,079
Other \| Weighted Average Useful Life (Years)
Amortizable intangible assets:
Weighted Average Useful Life (Years)	8 years

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS - Expected Amortization Expense (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remaining 2023	$ 30,130
2024	54,502
2025	43,427
2026	40,825
2027	39,689
2028	29,459
Thereafter	$ 94,067

DEBT - Schedule of Debt (Detail

DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Deferred financing costs	$ (9,912)	$ (10,844)
Long-term debt	761,612	760,537
Secured Debt \| Senior Secured Term Loan Facility due May 26, 2028
Debt Instrument [Line Items]
Long-term debt, gross	371,524	371,381
Secured Debt \| Senior Notes due June 2031
Debt Instrument [Line Items]
Long-term debt, gross	$ 400,000	$ 400,000

DEBT - Narrative (Details)

DEBT - Narrative (Details) - USD ($)					12 Months Ended
DEBT - Narrative (Details) - USD ($)	Mar. 24, 2023	Mar. 15, 2023	May 26, 2021	Aug. 28, 2020	Sep. 30, 2020	Mar. 31, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Loss on extinguishment of debt					$ 273,000
New Senior Secured Term Loan Facility \| Secured Debt
Debt Instrument [Line Items]
Debt face amount			$ 400,000,000
Annual amortization rate			1%
New Senior Secured Term Loan Facility \| London Interbank Offered Rate (LIBOR) \| Secured Debt
Debt Instrument [Line Items]
Debt instrument variable rate floor			0.50%
Debt instrument, basis spread on variable rate			2%
New Senior Secured Term Loan Facility \| London Interbank Offered Rate (LIBOR) \| Secured Debt \| One-month interest period
Debt Instrument [Line Items]
Credit spread adjustment		0.11448%
New Senior Secured Term Loan Facility \| London Interbank Offered Rate (LIBOR) \| Secured Debt \| Three-month interest period
Debt Instrument [Line Items]
Credit spread adjustment		0.26161%
New Senior Secured Term Loan Facility \| London Interbank Offered Rate (LIBOR) \| Secured Debt \| Six-month interest period
Debt Instrument [Line Items]
Credit spread adjustment		0.42826%
New Senior Secured Term Loan Facility \| Secured Overnight Financing Rate (SOFR) \| Secured Debt
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		2%
New Senior Secured Term Loan Facility \| Base Rate \| Secured Debt
Debt Instrument [Line Items]
Debt instrument variable rate floor			1.50%
Debt instrument, basis spread on variable rate			1%
Line of credit \| ABL Credit Facility \| Atkore International
Debt Instrument [Line Items]
Credit facility, aggregate commitments						$ 325,000,000
Credit facility available borrowing capacity						$ 322,406,000	$ 312,905,000
Line of credit \| Amended ABL Credit Facility \| Secured Debt
Debt Instrument [Line Items]
Debt instrument, extended term, period from amendment date			5 years
Debt instrument, extended term, period prior to maturity date			91 days
Line of credit facility, term, outstanding obligations threshold amount			$ 100,000,000
Line of credit \| Amended ABL Credit Facility \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Credit spread adjustment	0.10%
Line of credit \| Amended ABL Credit Facility \| London Interbank Offered Rate (LIBOR) \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.25%
Line of credit \| Amended ABL Credit Facility \| London Interbank Offered Rate (LIBOR) \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.75%
Domestic Line of Credit \| ABL Credit Facility \| Atkore International \| London Interbank Offered Rate (LIBOR) \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				1.75%
Domestic Line of Credit \| ABL Credit Facility \| Atkore International \| London Interbank Offered Rate (LIBOR) \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				2.25%
Domestic Line of Credit \| ABL Credit Facility \| Atkore International \| Base Rate \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				0.75%
Domestic Line of Credit \| ABL Credit Facility \| Atkore International \| Base Rate \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				1.25%
Domestic Line of Credit \| Amended ABL Credit Facility \| London Interbank Offered Rate (LIBOR) \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.25%
Domestic Line of Credit \| Amended ABL Credit Facility \| London Interbank Offered Rate (LIBOR) \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.75%
Domestic Line of Credit \| Amended ABL Credit Facility \| Base Rate \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			0.25%
Domestic Line of Credit \| Amended ABL Credit Facility \| Base Rate \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			0.75%
Foreign Line of Credit \| ABL Credit Facility \| Atkore International
Debt Instrument [Line Items]
Line of credit facility, unused capacity, commitment fee percentage (percent)				0.375%
Foreign Line of Credit \| ABL Credit Facility \| Atkore International \| Bankers Acceptance Rate \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				1.75%
Foreign Line of Credit \| ABL Credit Facility \| Atkore International \| Bankers Acceptance Rate \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				2.25%
Foreign Line of Credit \| ABL Credit Facility \| Atkore International \| Prime Rate \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				0.75%
Foreign Line of Credit \| ABL Credit Facility \| Atkore International \| Prime Rate \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				1.25%
Foreign Line of Credit \| Amended ABL Credit Facility \| Line Of Credit Facility, Commitment Option One
Debt Instrument [Line Items]
Line of credit facility, unused capacity, commitment fee percentage (percent)			0.375%
Foreign Line of Credit \| Amended ABL Credit Facility \| Line Of Credit Facility, Commitment Option Two
Debt Instrument [Line Items]
Line of credit facility, unused capacity, commitment fee percentage (percent)			0.30%
Foreign Line of Credit \| Amended ABL Credit Facility \| Line Of Credit Facility, Commitment Option Three
Debt Instrument [Line Items]
Line of credit facility, unused capacity, commitment fee percentage (percent)			0.25%
Foreign Line of Credit \| Amended ABL Credit Facility \| Bankers Acceptance Rate \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.25%
Foreign Line of Credit \| Amended ABL Credit Facility \| Bankers Acceptance Rate \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.75%
Foreign Line of Credit \| Amended ABL Credit Facility \| Prime Rate \| Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			0.25%
Foreign Line of Credit \| Amended ABL Credit Facility \| Prime Rate \| Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			0.75%

FAIR VALUE MEASUREMENTS - Asset

FAIR VALUE MEASUREMENTS - Assets and Liabilities Measured at Fair Value (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Level 1
Assets
Cash equivalents	$ 260,644	$ 291,757
Level 2
Assets
Cash equivalents	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Estim

FAIR VALUE MEASUREMENTS - Estimated Fair Value of Financial Instruments Not Carried at Fair Value (Details) - Secured Debt - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	$ 773,000	$ 773,000
Fair Value	730,147	689,115
Senior Secured Term Loan Facility due May 26, 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	373,000	373,000
Fair Value	374,399	370,203
Senior Notes due June 2031
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	400,000	400,000
Fair Value	$ 355,748	$ 318,912

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Purchase obligation for the rest of fiscal year 2023	$ 243,801
Purchase obligation for fiscal year 2024	$ 10,463

GUARANTEES (Details)

GUARANTEES (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Performance Guarantee, Workers' Compensation and General Liability Policies
Guarantor Obligations [Line Items]
Guarantees	$ 2,594
Surety bond
Guarantor Obligations [Line Items]
Guarantees	$ 26,394

SEGMENT INFORMATION -Schedule o

SEGMENT INFORMATION -Schedule of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Segment Reporting Information [Line Items]
Net sales	$ 895,934	$ 982,573	$ 1,729,755	$ 1,823,374
Electrical
Segment Reporting Information [Line Items]
Net sales	680,955	758,347	1,319,660	1,398,691
Safety & Infrastructure
Segment Reporting Information [Line Items]
Net sales	214,979	224,226	410,095	424,683
Operating Segments
Segment Reporting Information [Line Items]
Net sales	895,934	982,573	1,729,755	1,823,374
Adjusted EBITDA	290,077	359,887	567,317	666,866
Operating Segments \| Electrical
Segment Reporting Information [Line Items]
Net sales	680,955	758,347	1,319,660	1,398,691
Adjusted EBITDA	256,883	330,970	500,720	610,517
Operating Segments \| Safety & Infrastructure
Segment Reporting Information [Line Items]
Net sales	214,979	224,226	410,095	424,683
Adjusted EBITDA	33,194	28,917	66,597	56,349
Intersegment Sales
Segment Reporting Information [Line Items]
Net sales	(85)	(1,589)	(228)	(2,981)
Intersegment Sales \| Electrical
Segment Reporting Information [Line Items]
Net sales	10	1,530	10	2,869
Intersegment Sales \| Safety & Infrastructure
Segment Reporting Information [Line Items]
Net sales	$ 75	$ 59	$ 218	$ 112

SEGMENT INFORMATION - Reconcili

SEGMENT INFORMATION - Reconciliation of Operating Segment Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Segment Reporting Information [Line Items]
Unallocated expenses	$ (14,036)	$ (13,721)	$ (27,431)	$ (27,690)
Depreciation and amortization	(28,598)	(19,994)	(54,566)	(40,040)
Interest expense, net	(8,475)	(7,514)	(17,963)	(14,432)
Stock-based compensation	(6,863)	(6,128)	(12,133)	(9,555)
Other	(4,547)	(440)	(5,615)	(1,241)
Income before income taxes	227,558	312,090	449,609	573,908
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	290,077	359,887	567,317	666,866
Operating Segments \| Electrical
Segment Reporting Information [Line Items]
Adjusted EBITDA	256,883	330,970	500,720	610,517
Operating Segments \| Safety & Infrastructure
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 33,194	$ 28,917	$ 66,597	$ 56,349

SEGMENT INFORMATION - Schedule

SEGMENT INFORMATION - Schedule of Long-lived Assets and Net Sales By Geography (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Disaggregation of Revenue [Line Items]
Net sales	$ 895,934	$ 982,573	$ 1,729,755	$ 1,823,374
United States
Disaggregation of Revenue [Line Items]
Net sales	799,562	895,585	1,549,649	1,652,983
Other Americas
Disaggregation of Revenue [Line Items]
Net sales	23,063	24,649	43,617	47,136
Europe
Disaggregation of Revenue [Line Items]
Net sales	61,789	52,709	113,819	103,162
Asia-Pacific
Disaggregation of Revenue [Line Items]
Net sales	$ 11,520	$ 9,630	$ 22,670	$ 20,093

SEGMENT INFORMATION - Schedul_2

SEGMENT INFORMATION - Schedule of Net Sales From External Customers by Product Category (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 25, 2022	Mar. 31, 2023	Mar. 25, 2022
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 895,934	$ 982,573	$ 1,729,755	$ 1,823,374
Electrical
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	680,955	758,347	1,319,660	1,398,691
Electrical \| Metal Electrical Conduit and Fittings
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	128,322	153,049	239,480	302,925
Electrical \| Electrical Cable & Flexible Conduit
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	129,785	137,244	253,511	252,939
Electrical \| Plastic Pipe and Conduit
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	323,139	374,775	639,304	663,764
Electrical \| Other Electrical products
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	99,709	93,279	187,365	179,063
Safety & Infrastructure
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	214,979	224,226	410,095	424,683
Safety & Infrastructure \| Mechanical Pipe
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	98,727	112,818	177,501	224,061
Safety & Infrastructure \| Other Safety & Infrastructure products
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 116,252	$ 111,408	$ 232,594	$ 200,622

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Subsequent Event shares in Millions, $ in Millions	1 Months Ended
	May 09, 2023 USD ($) shares
Subsequent Event [Line Items]
Stock repurchased (in shares) \| shares	0.8
Stock repurchased value \| $	$ 102.5