Question: what is the difference between 3 phase 3 wire and 4 wire?
Answer: In a 3 phase 3 wire supply the conduit was used as a neutral & ground. In 3 phase 4 wire, the conduit is no longer used as a neutral or ground, and the supply has 3 'hots', a neutral and a ground wire. ... While 3-phase 4- wire system has neutral .