Ground Fault Circuit Interrupters

   Ground faults happen when the live wire contacts a grounded surface like the side of a junction box. Ground fault circuit interrupters (GFCIs) protect you from shock if you contact a live wire while you're grounded, say, when standing in a tub full of water. GFCIs work by constantly comparing the amount of current coming in through the live wire to the amount going out through the neutral wire. When slight changes occur the unit shuts off in a fraction of a second. You'll still feel a shock but it will be very brief.
   GFCIs are required for receptacles close to waterùnear sinks, tubs and showersùand on all outdoor receptacles. They're also available as breaker switches to protect an entire circuit.