Carlon manufactures the most complete line of nonmetallic conduits and fittings in the electrical industry. Standard couplings are for use with Schedule 40 and Schedule 80 Conduit. Socket/Socket Socket type for joining nonmetallic conduit All socket fittings should be attached using Carlon solvent cement Using Carlon fittings with Carlon nonmetallic conduit insures system integrity. The Carlon 1-1/4-inch Schedule 40 Standard Electrical Coupling is a socket-type coupling for joining schedule 40/80 non-metallic conduit. It will not rust or corrode and is both non-metallic and non-conductive.