This is a Ground Fault Circuit Interrupter.
This device replaces a conventional receptacle outlet. Should someone come in contact with a live (hot) wire, this GFCI will detect a currect leakage as little as 5 milliamps and will shut the power off almost immediately (1/40 of a second). The National Electric Code (NEC) requires the use of GFCI outlets in kitchens, bathrooms, garages, basements and near swimming pools. Caution: Use this device only with copper or copper clad wire. With aluminum wire use only devices marked CO/ALR. UL listed (E243387). Complies with 2003 UL requirements.
Protects against shocks from: