SEGMENT INFORMATION - Schedule of Net Sales From External Customers by Product Category (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 26, 2026	Jun. 27, 2025	Jun. 26, 2026	Jun. 27, 2025
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	$ 794,800	$ 735,045	$ 2,181,724	$ 2,098,367
Electrical
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	578,300	521,306	1,580,298	1,479,331
Electrical \| Metal Electrical Conduit and Fittings
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	132,061	121,118	379,398	335,189
Electrical \| Electrical Cable & Flexible Conduit
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	133,946	132,431	369,915	366,889
Electrical \| Plastic Pipe and Conduit
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	156,270	176,098	443,868	499,123
Electrical \| Other Electrical products
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	156,023	91,659	387,117	278,130
Safety & Infrastructure
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	216,500	213,739	601,426	619,036
Safety & Infrastructure \| Mechanical Pipe
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	72,648	82,830	212,087	219,619
Safety & Infrastructure \| Other Safety & Infrastructure products
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net sales	$ 143,852	$ 130,909	$ 389,339	$ 399,417