240 Volt Home Wiring. Codes now call for four wiresblack and red hot wires a white neutral wire and a ground wire. Some older receptacles use only three wires.
The incoming 240V power is split into two legs. Typically a 240 volt heater will have three wires in a junction box or connection area. Appliances which use straight 240 current such as electric water heaters or rotary phase converters also have three wires.
A 240-volt 3-wire receptacle has three prongs two hot and one ground to accept a 3-prong plug.
Codes now call for four wiresblack and red hot wires a white neutral wire and a ground wire. It all depends on circuit thats being assembled. Electrical Wiring for 240 Volt Circuits and Switches. Appliances that belongs to this group does not require 120 volt circuit.