Wiring Diagrams for Electrical Receptacle Outlets - Do-it Wiring a 20-Amp 240-Volt Appliance Receptacle. This outlet is commonly used for a heavy load such as a large air conditioner. The outlet should be wired to a dedicated 20-amp/240-volt circuit breaker in the service panel using 12|2 awg cable. With this wiring, both the black and white wires are used to carry 120 volts each and the white wire is wrapped with electrical tape to label it hot. Alternating Current in Electronics: Hot, Neutral, and To prevent that from happening, the receptacles are polarized, which means that the neutral prong is wider than the hot prong, there’s only one way to plug a polarized plug into a polarized receptacle. That way, you can always keep track of which wire is hot and which is neutral.