What is a GFCI
GFCI's are electrical devices designed to detect ground faults or stray current. Ground faults occur when electrical current is "leaking" somewhere outside o the path where the current is suppose to flow. If your body provides the path to the ground for the leakage, you could be burned, severely shocked, or electrocuted.
The GCFI constantly monitors electricity flowing in a circuit to sense any imbalance in the current. If the current going into the circuit differs by even a small amount from that returning, the GFCI switches off power to that circuit.
The GFCI interrupts power in a fraction of a second to prevent your receiving a lethal dose of electricity. Even with a GFCI, you might be shocked, but the GFCI limits your exposure to chock and helps protect against serious injury and electrocution. GFCIs should be tested periodically to determine that they are working properly.
Principles of Operation
The GFCI sensing system continuously monitors the current balance in the ungrounded 'hot' conductor and the neutral conductor. If the current in the neutral wire becomes less than the current in the 'hot' wire, a ground fault could exist. A portion of the current returns to the supply by some path other than the neutral wire. With a current imbalance as low as 6 milliamperes, the GFCI will interrupt the circuit and this will be shown by a trip or 'off' indicator on the device.
The GFCI does not limit the magnitude of the ground-fault current. It limits the time that a current of given magnitude can flow. The trip level-time combinations are based on physiological data established for avoiding injury to normal healthy persons.
Where Are They Required in a Dwelling Unit
- Bathrooms adjacent to the sink area
- Garages and grade level portion of unfinished accessory buildings or work areas
- Outdoors at grade level or accessible. Accessible/ Able to walk up to or reach without a ladder
- Crawl spaces (where mechanical equipment is located)
- Unfinished basements (only one is required)
- All kitchen counter top level devices
- Wet bars within 6-foot of the sink (counter top level devices).
- When you change an existing outlet in any of the above listed locations.
How to Obtain GFCI Protection
- Ground fault sensing receptacles
- Ground fault sensing circuit breaker
If a small device were installed in every home in the United States, more than two-thirds of all residential electrocutions could be prevented. The device is called a ground fault circuit interrupter, or GCFI.
When GFCIs Are Required by Law
In homes built to comply with the current National Electrical Code, GFCI protection is required for:
- Most outdoor receptacles (since 1973)
- Bathroom receptacles circuits (since 1975)
- Garage wall outlets (since 1978)
- Some kitchen receptacles (since 1987)
- Outlets in crawl spaces and unfinished basements (since 1990)
You should inspect your home to see if GFCIs are installed in these areas.
Different Types of GFCIs
Circuit breaker type GFCIs can be added in electrical panels to replace ordinary circuit breakers. They may be installed by a qualified electrician.
Replace type GFCIs may be used in homes protected by fuses or circuit breakers. They should be installed by an electrician wiring practices.
Portable GFCIs simply plug into the receptacle and require no special knowledge or equipment to install. They can be used in any receptacle.