The standard 240-volt portable-generator plug is a four-wire NEMA L14-30 plug that can be found in most hardware stores. The four wires consist of two "hot" wires (which are normally black but are sometimes red); a "neutral" wire (normally white); and a ground wire (usually green). To make your installation easier, check your generator owner's manual to ensure that a NEMA L14-30 will fit.
Wire the Plug
Remove the screws from the plug and remove the cover.
Use the knife to remove the outer covering on the cable, so the four inner wires are 1 1/2 inches in length.
Use the wire strippers to strip a half-inch of insulation off each of the four wires.
Loosen the screw connectors on each of the four prongs of the plug with a screwdriver.
Place the black wires under the screw connectors on the "hot" prongs and tighten them with a screwdriver.
Place the white wire under the screw connector on the "neutral" prong and tighten it with a screwdriver.
Place the green wire under the screw connector on the "ground" prong and tighten it with a screwdriver.
Replace the cover and tighten the screws with a screwdriver.