: a constant potential system of electric distribution in which lamps or other receiving devices are connected between either one of two main conductors and a third wire and motors and heavy duty appliances are usually connected across the main conductors.

What is 3 wire and 4 wire system?

Three phase, 4-wire distribution system

This system uses star connected phase windings and the fourth wire or neutral wire is taken from the star point. If the voltage of each winding is V, then the line-to-line voltage (line voltage) is √3V and the line-to-neutral voltage (phase voltage) is V.

What does a three wire system protect you from?

The three-wire system guards against thermal and shock hazards, utilizing live/hot, neutral, and earth/ground wires, and grounding the neutral wire and case of the appliance.