Things You'll Need
Dual-voltage appliances that draw up to 50 amps often plug into a NEMA 10-50R, a NEMA 10-50 receptacle. The 10-50R only accepts a NEMA 10-50P's 2-1/8-inch-diameter 10-50 plug with three straight-blade prongs. A 10-50R three-pole three-wire 125/250-volt 50-amp receptacle has three prong slots containing two hot terminals and a neutral terminal. The neutral's vertically aligned slot sits at the bottom center of the receptacle's face. The two hot slots sit at a 45-degree angle to the neutral; the top of the hot slots face each other and point to the top of the receptacle.
Remove 1/2 an inch of the insulation on the three wires inside of the NEMA 10-50R with a utility knife or wire strippers. The 8-gauge or larger wire required for 50-amp circuits often uses braided wire strands. Utility knives strip braided wire with less effort than wire strippers do.
Examine the NEMA 10-50R. The letters stamped in the 10-50R's housing identify each terminal.
Loosen the NEMA 10-50R's W terminal screw with a slotted screwdriver. A 10-50R usually uses a silver screw on its W terminal. Push the neutral wire under the 10-50R's W terminal and tighten the screw. In most cases, the neutral wire uses white insulation.
Loosen the NEMA 10-50R's X terminal screw with a slotted screwdriver. A 10-50R should have a gold screw on its X terminal. Slide either one of the hot wires under the 10-50R's X terminal and tighten the screw. The interchangeable hot wires often use black or red insulation.
Loosen the NEMA 10-50R's Y terminal screw with the slotted screwdriver. A 10-50R's Y terminal should have a gold screw. Slip the remaining hot wire under the 10-50R's Y terminal and tighten the screw.