Q: What are the buttons for?

A: Pressing the "test" button will simulate a ground fault in the circuit and if working properly should result in power being cut to the circuit. It should also cause the "reset" button to pop out. Pressing the "reset" button should restore power to the circuit.

Q: How do GFCIs work?

A: GFCI devices contain circuitry that monitors and compares the current entering the circuit on one leg to the current leaving the circuit on the other leg. It should be exactly the same. If there is more current entering than leaving, some of the power must be "leaking", or finding another route to ground. This other route might be through your body, so the device opens the circuit and stops the flow.

Q: How do they differ from regular fuses or circuit breakers?

A: They are both designed to open circuits in an emergency, but they are different emergencies. Household overcurrent protection (fuses and breakers) are designed to open a circuit if it is overloaded or shorted out. Fuses and breakers in residential branch wiring generally range from 15 to 50 amperes, which means that the current flowing through the circuit must be at least that high (and sometimes it is much more) before the circuit is opened. Unfortunately, we cannot tolerate that level of current flowing through our bodies. It takes only a few amps at household voltages to cause serious injury or death. Their purpose, then, is not to prevent shock but to protect the branch wiring from overheating, and to reduce the danger of fire should a defect in the system or a faulty appliance cause a short circuit. In contrast, GFCI devices are designed to stop current flow when extremely small differences (.005 amperes) are detected between the current going in and the current going out. The power is interrupted before electrocution can occur.

A: The risk of shock due to ground fault is greatest in areas exposed to water or moisture. Therefore, circuits in kitchens (except to refrigerators and freezers), bathrooms, utility areas and garages should have GFCIs. Also, any outdoor outlets should be protected, as well as circuits supplying power to spas and hot tubs.

Q: Can my home be retrofitted with GFCI devices?

A: Yes, and I highly recommend it. It is a very sensible upgrade to an older home (in new homes GFCI are required by code) and provides a big dividend in safety and peace of mind. Even when the original circuitry is of the old ungrounded type, a GFCI device will function, although it is more difficult to test. The devices themselves are inexpensive (about $10), so the main cost involved is the time of a Licensed Electrical Contractor to do the job. All work should be done safely by an expert.