I want to protect my family from electrical shocks. I heard that there is a special type of outlet that does this. Can you give me more information?
The special device you describe is called a "ground fault circuit interrupter", or GFCI. It is designed to prevent accidental electric shocks. The way it works is ingeniously simple... a circuit within the outlet measures the difference between the electrical current going into the outlet (via the "hot" wire) and out of the outlet (via the "neutral" wire). All electrical current flows from the hot wire, through the appliance and then back to the "ground" via the neutral wire. Hence the difference in current is very small. Under normal circumstances, a GFCI-protected outlet acts just like a regular outlet.
Electrical shocks occur when electricity takes an alternate path to the ground than the neutral wire. It's easy to imagine a situation when this would happen. You drop a hair dryer into a sink full of water, or (a classic movie murder method) a radio "accidentally" drops into the Jacuzzi! Without a GFCI, there is a good chance of shock or even electrocution since a standard circuit breaker may not immediately turn off the power. This is where the GFCI shines... it will detect that the current is not flowing the right way and turn off the power in a fraction of a second!
There are two types of GFCIs... one that is used to replace an existing outlet and a second that replaces a circuit breaker in your main electrical service box. They function the same, but one circuit breaker-type can protect all outlets in its circuit. In newer homes, the electricians often design the wiring so that multiple bathrooms share the same GFCI circuit breaker! In many older homes, though, separate outlet-type GFCIs will probably be needed for each bathroom or kitchen outlet. (A note: outlet GFCIs can also protect more than one outlet depending on your home's wiring. Consult the instructions that come with the GFCI for the wiring requirements and limitations.)
All GFCIs have two push buttons on the face... one labeled "test" and a second labeled "reset". Pressing the test button will trip the GFCI if it is functioning properly. Once tripped, no electricity will flow from the outlet. The "reset" button is used to reactivate the GFCI after it has been tripped. The GFCI will not reset if (1) the cause of the electrical short is still present, (2) there is no electricity coming into the outlet or (3) the GFCI is incorrectly wired. Correct wiring is important and the directions should be followed to the letter!
GFCIs are normally used to protect outlets near water supplies, such as bathrooms and kitchens, as well as all outlets outside the home. They are also used in garages, basements and other locations that may present shock hazards. Local electrical codes vary, so your best source of information would be your local building inspector or a friendly electrician!
One question that frequently arises is the issue of grounding. Some older homes do not have third "grounding" wire in their electrical circuits. This is not a problem... GFCIs do not need a grounding wire to function properly.
However, there is a little fly in the ointment. Be cautious when using appliances that require a ground! These appliances are easily identifiable by the third rounded "prong" on the electrical plug. (Raise your hands... how many of you have used one of those little adapters to plug a three-prong appliance into a two-prong outlet?)
Never fear... the GFCI will still work! But you still might receive a slight momentary shock if you are touching metal parts of the appliance when the short-circuit occurs! This is because YOU are acting as the only path from the appliance to ground. As fast as the GFCI is, electricity is faster. Though the level of the shock would typically be slight, there is a small chance of involuntary muscular contraction, which could cause indirect injury or even death. Imagine getting an unexpected shock from your electric drill when standing on a tall ladder! So be careful and, whenever possible, use double-insulated tools that do not require a ground in these situations!
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