GFCI (ground fault circuit interrupters) is a specific term for products which are used for personnel protection. UL Standards for Class A GFCI listing requires these devices to trip when they sense a ground fault of 6mA or more. They must not trip on currents as low as 4mA. The actual maximum tripping time (for 6 to 264mA) is found by the formula T = (20/I)^1.43, where T is in seconds and I is in mA. UL also requires the test button on the GFCI to simulate a fault thereby indicating proper operation.
ALCI (appliance leakage circuit interrupter), a subset of GFCI devices, are intended for use with appliances such as hair dryers.
GFPE (ground fault protection - equipment)and ELCI (equipment leakage circuit interrupter) are generic terms used to describe devices which protect at the 30mA level.
GFP (ground fault protection) is a catch all phrase for any ground fault sensing device. Many engineers use this term to define protection used for service entrance equipment, feeders, and large branch circuits. These devices are characterized by trip levels measured in Amps (not mA) and trip times in seconds. Also, these devices rarely interrupt the current directly, they are usually used to activate remote tripping of other protective devices.
