A GFCI-protected circuit may trip due to water, conductive dust, worn-out insulation and soft grounds. As per the electrical code, ground fault circuit interrupters are often installed in outlets where there is exposure to water, such as bathrooms, kitchens, laundry rooms, garages and outdoor receptacles.
A GFCI protects users from electric shock or electrocution by cutting off the outlet's power if it detects a current differential between the line current to the load and the neutral current returning from the load. Current differentials may occur when an appliance user comes into contact with water, such as a wet floor, turning the appliance user into an inadvertent path for electricity to travel from the outlet to the ground. Current differentials as little as 5 milliamperes are enough to trip GFCIs. Currents as low as 10 milliamperes can cause painful to severe electric shock, while 75 milliamperes can trigger ventricular fibrillation that can be fatal. GFCIs are safety devices that ensure these do not happen.