What is the purpose of an RCD?
As far as safety goes, electricity is one danger that you don’t want to leave up to chance. A safety switch(Also known as an RCD-Residual Current Device) is designed to activate and trip(turn off) the circuit if current leakage is detected, all in a fraction of a second. The purpose of a safety switch is to protect you, your loved ones and anybody visiting/working at your property or workplace from an electric shock which can potentially kill.
Safety switches will turn off when there is a faulty appliance, water in an electrical fitting, rodent’s chewed through cables or even something as simple as drilling a screw into a wall to hold your picture frame up that nicks a screw going in.