Called GFI’s for short, this device could save your life.   

Have you ever received an electrical shock? It’s startling, to say the least. If you’re
still with us to read this, it’s because you were insulated from the ground. If you had one hand on a sink or were standing in a puddle outdoors, the result could possibly be fatal. 

Aside from overloading a circuit, the only other way to trip the overload device is a dead short. This is accomplished by making a direct connection between the hot and neutral wires. Driving a nail into a wire behind the wall is one example that comes to mind. Your body, however, is not a good conductor so your contact between hot and ground will not trip the breaker… and you will be unable to move your muscles to release yourself. Enter the GFI’s. An average household circuit carries 15 amps. 1/10th of an amper can kill you if it passes through your body for as little as two seconds.  Be sure to consult a licensed Electrician for a more detailed explanation on how GFI’s work.