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Handyman Q&A

The GFCI Breaker Is a Safety Refinement


Question: I'm a do-it-yourselfer, and I'd like to know more about Ground Fault Circuit Interrupter, or GFCI, protection and the relationship it has with ground and neutral wires. If I use a small one-quarter-watt electrical circuit tester, I can use the metal junction box or the ground slot as a neutral. When doing the same test using a 25-watt incandescent bulb, however, the GFCI will trip. Why?

Answer: The neutral wire is grounded, but it is not the grounding wire. The neutral wire is needed to close the circuit. This allows the current in the branch circuit to flow from the electrical service panel through the appliance and back to the grounding bar in the service panel.

The grounding wire is a safety feature. It connects to ground components that do not normally carry a current, such as a metal appliance case. If an electrical short develops and the case becomes electrified, the grounding wire directs the current safely to ground rather than shocking a person who is touching the metal surface.

The GFCI is a safety refinement. Under normal conditions, the current is equal in the hot and neutral lines. The GFCI breaker or GFCI outlet receptacle has a sensing element that monitors the current in the hot and neutral lines of a branch circuit. If the GFCI senses a current difference between the hot and neutral line as small as 5 milliamps (5/1,000 of an ampere), it automatically trips. The circuit is opened, and current stops flowing within a fraction of a second.

By testing the circuit using the hot leg and the grounded junction box or ground slot in the outlet, you alter the current flow between the hot and the neutral legs of the circuit. The GFCI doesn't trip with the one-quarter-watt tester because it draws 2.1 milliamps, which is less than the GFCI's 5-milliamp threshold. The GFCI is tripped when using the 25-watt bulb because that test draws 208 milliamps. Based on your test, the GFCI is working properly.


Q: We recently moved to a home that has Kohler gold-plated bathroom fixtures. Evidently, they had been cleaned with an abrasive solution because all the finish is off them. Is there anything we can do to restore their gold luster?

A: The finish on Kohler faucets is made to resist the effects of soaps and hard water. It will not, however, withstand an abrasive cleaner. Unfortunately, there is nothing you can do to restore the gold luster other than having the parts replated, and I doubt that this cost would be justified. Unless the finish on the entire faucet has been abraded, you might consider replacing only the affected parts. Contact your local plumbing supply store for help.

To submit a question, write to Popular Mechanics, Reader Service Bureau, 224 W. 57th St., New York, N.Y. 10019.

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