Thomas & Betts 145 Conduit Locknut Brand: Thomas & Betts. Part Number: 145. T&B Conduit Locknut, 1-1/2 in, For Use With: Rigid/IMC Conduits, Steel, 2-1/2 in H x 13/64 in THK. Additional Description: TB -145 1-1/2 INCH STEEL LOCKNUT. Catalog Description: 1-1/2 Inch Steel Locknut for Use With Rigid/IMC Conduit..