Degrees of protection against shocks resistance

 
Circuit-breaker
Protect the electric material against the overcharge (request for too high current intensity).

Différentiel
A residual current device (RCD), or residual current circuit breaker (RCCB), is an electrical wiring device that disconnects a circuit whenever it detects that the flow of current is not balanced between the phase ("hot") conductor and the neutral conductor. The presumption is that such an imbalance may represent current leakage through the body of a person who is grounded and accidentally touching the energized part of the circuit.
Rappel : Le matériel alimenté par ce dispositif doit impérativement être raccordé à la terre.