The Ground Fault Circuit Interrupter plays a critical role in everyday electrical safety. The subsequent details describe GFCI devices

1-What is a GFCI?
2-Where are they required?
3-When to test your GFCI.

What is a GFCI?

1-You may not think of the GFCI as an electronic device, but it is the most sensitive and important life saving device you can find wherever electricity is used. GFCI's are designed to minimize and reduce the chance of electrocution when using electrical appliances.

The sensitive electronic circuits inside GFCI's have two differential sensing circuits. The first one detects the amount of current being used by the tool, hair dryer etc. The second sensing circuit detects the amount of current returning to the power supply. When these two detecting circuits do not see the same amount of current, the leakage current must be returning to ground some other way. If that leakage current flows thru you, a lethal shock is possible. GFCI's are designed to detect leakage and eliminate or stop a lethal shock and shut off within 1/40th of a second. The maximum amount of leakage current is about 4 to 6 mA (0.004 to 0.006 Amperes). 0.010 Amps can be lethal.

There are many variations of GFCI's manufactured. You will find receptacles, plugs, extension cords and breakers with GFCI protection. All of these variations work on the same principle. The 2 way flow of electrical current is monitored and if there is a slight imbalance on how much electrical current returns back to the source, it's designed to shut off.

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Where are they required?

2- GFCI products are generally required where water and electricity are used in close proximity. Some typical examples are: Bathrooms, laundry rooms, outdoors, pools, saunas, hot tubs and most construction sites. Electrical tools and or appliances and water just do not mix. Would you cut the grass in the early morning dew with an electric lawn mower in your bear feet? Some people would not think of the possibility of electric shock. Some portable products like power washers are manufactured with a GFCI type plugs. That is why the Canadian Electrical Code mandates GFCI in many locations, to protect people.

Ontario in January 2003 introduced a new requirement for GFCI to be installed within 1 meter of any Kitchen Sink. This new requirement is not just for residential applications. Hotels, Motels, Commercial Kitchens etc are now required to comply. Check with your local inspection authority.

GFCI types: Manual Reset and Automatic Reset.

A manual reset type does not provide power when it is initially powered. This type is commonly used on power tools where if there were a power failure or when a tool is initially plugged in the tool would not turn on again and possibly injure someone or damage something. Automatic versions imply that when power is first supplied or power failure occurs, the device keeps providing protection. GFCI's in bathrooms are the automatic type. It would be a nuisance to reset all GFCI receptacles in your house if there was a power failure. Would you always remember to reset that GFCI that protects your basement sump pump? Automatic reset are used when the return of power would not be a hazard.

3-When to test your GFCI

GFCI's should be tested monthly.
Simply push the TEST button.
The GFCI will self test and trip.
Reset will re-energize the unit.
Keep a record.
Always replace a defective unit ASAP.