One of the receptacles many industrial-size generators have requires a NEMA L14-20P, a three-pole four-wire plug. The L14-20P plugs into a NEMA L14-20R, which supplies either a 125- or 250-volt 20-amp electric supply. The NEMA L14-20P has four evenly spaced curved prongs. One, the ground prong, has a small locking tab that angles 90 degrees toward the outside. The two hot prongs, on each side of the ground prong, are wider than the neutral prong. The NEMA L14-20P has a 2-1/4-inch-wide plug face.

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Step 1

Remove the last 3/8 inch of the insulation from the ends of the four wires entering the NEMA L14-20P with wire strippers. Each wire uses color-coded insulation.

Step 2

Locate the NEMA L14-20P's terminal identification tags. These are the letters stamped above each wire terminal in the plug's housing: G, W, X and Y. The bolt on the G terminal has green paint.

Step 3

Loosen the NEMA L14-20P's G terminal with a Phillips screwdriver. Wrap the ground wire around the L14-20P's G terminal bolt and tighten the bolt. The ground wire usually has green insulation.

Step 4

Loosen the NEMA L14-20P's W terminal with the Phillips screwdriver. Wrap the neutral wire around the L14-20P's W terminal bolt and tighten the bolt. The neutral wire usually has white insulation.

Step 5

Loosen the NEMA L14-20P's X terminal with the Phillips screwdriver. Wrap a hot wire around the L14-20P's X terminal bolt and tighten the bolt. The interchangeable hot wires usually have black or red insulation.

Step 6

Loosen the NEMA L14-20P's Y terminal with the Phillips screwdriver. Wrap the remaining hot wire around the L14-20P's Y terminal bolt and tighten the bolt.