A GFCI or Ground Fault Circuit Interrupter is a special breaker or receptacle providing extraordinary protection from shock in areas that you can come into contact with water & electricity at the same time. The GFCI can tell if current as low as 5 milliamps is “leaking” out of a circuit to ground. If the GFCI senses this leakage it will de-energize the circuit due to amperage imbalance. If this current is “leaking” through your body to ground because you have touched an energized piece of equipment you may feel a shock but it will be a very short duration before the circuit is turned off by the GFCI. These receptacles have “test” and “reset” buttons and are found in bathrooms, kitchens, laundry areas, garages, and unfinished basements.