A NEMA L14-30 plug has four prongs: two hot, one neutral and a ground. The curved prongs mount to the L14-30 plug's face in a cross pattern with the two hot prongs on the sides, the neutral at the top and the ground positioned on the bottom. The ground prong contains the locking tab, which angles toward the center of the plug's face. The tab locks the plug into the receptacle when turned clockwise. A NEMA L14-30 connects to a 250-volt 30-amp electrical circuit with four-strand 10-gauge wire.
Remove 3/8 inch of the insulation from the wires entering the NEMA L14-30 plug with a pair of wire strippers. The color-coded insulation indicates the wire's purpose.
Loosen the NEMA L14-30's wire terminal screws with a slotted screwdriver. The slotted terminal screws mount to the side of the wire terminals.
Push the stripped end of the green wire into the NEMA L14-30's ground terminal, then tighten the terminal with the slotted screwdriver. The ground terminal, located on the bottom of the NEMA L14-30's face, has a green screw.
Push the stripped end of the white wire into the NEMA L14-30's neutral terminal, then tighten the terminal with the slotted screwdriver. The neutral terminal, located on the top of the NEMA L14-30's face, has a silver-colored screw.
Push the stripped ends of the hot wires into the NEMA L14-30's hot terminals, then tighten the terminals with the slotted screwdriver. The interchangeable hot terminals, located on the sides of the the NEMA L14-30's face, have gold- or brass-colored screws. The hot wires either have black insulation on both wires, or black on one wire and red on the other.