What condition is 4P circuit breaker used in?

Jason

The entry of three-phrase power cord of TT and IT ground system should be displaced to 4P circuit breaker. It means electronic device with a pair of power supplies unit (one use, one backup) have supplied inversely, and its pair of the electric wires has been installed with RCD, that each switches on its pair of the electric wires must be 4P circuit breakers.