How to Wire a 4-Prong 240-Volt Twist-Lock Plug | Hunker Generator twist-lock plug wiring, for example, is no different than the wiring for a conventional four-prong plug with the same current rating. To understand how to wire a 240-volt plug, it helps to have an understanding of 240-volt electrical connections in general. How to Wire a 240 Volt Portable Generator Plug | Hunker 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). Connecting a Generator to House - generators for home use WIRING A GENERATOR 4-PRONG CABLE TO 4-PRONG OUTLET. Newer homes may have 4-prong 125/250V drier outlet NEMA 14-30R. It provides a separate ground hole besides L1, L2 and N (see diagram). For our task it has the right number of leads, but a wrong geometry. How do I re-wire a 4 wire plug to a 3 wire plug for a 220v I am replacing a 220v washer/dryer combo unit at work and the old washer/dryer has a 4 wire receptacle. The new (used) 220v washer/dryer has a 3 wire plug. So, my question is: Do I connect the neutral (white) wire or the bare (ground) to the receptacle plug with the red and black? And what do I do with the left over wire? Just cap or “unwire” from the sub-panel?