GFCI Breaker

Red Rover, Red Rover, Send Tige Over


Last Changed 2/11/2007
What is a GFCI? Most of us know that GFCIs (Ground Fault Circuit Interrupter) are used to protect us but most of us do not know why. This section is to give a brief discussion of GFCIs and why we should use then. Most of us think of AC electricity as having a Hot wire (usually Black or Red) and a Neutral wire (usually White). We think of the Hot wire as having voltage while the Neutral wire does not. In terms of reference to Ground, this is true. However both wires carry current and current is what can kill you. In AC (Alternating Current), the current travels from the source, through the Hot lead, through the appliance, and finally through the Neutral wire back to the source. Then the current reverses direction going through the Neutral and back through the Hot wire. This happens 60 times a second.
	A GFCI is a dual pole circuit breaker with addition circuitry. The main concept of the GFCI is that, when all things are working correctly, all the current that travels out one wire should return through the other wire (Hot to Neutral or Neutral to Hot). By sensing the out-going current and comparing it to the return current, the GFCI can determine if things are working correctly. When things are not correct, some or all of the current is returning to the source through other paths like electrical shorts or most importantly through you.
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If the GFCI senses as little as 5 milli-amperes difference between the outgoing and incoming circuit legs, it will open the circuit breaker. A current flow of only 10 milli-amperes through you can kill you. How do you use them? There are two buttons on the GFCI. The Red button pops out when the GFCI detects and current imbalance and opens the circuit. Pressing the Red button back in with reset the circuit. This should be done only after the cause of the current imbalance has been determined. The other button is to test the circuitry. Pressing the other button (usually black) will cause the GFCI circuitry to sense a current imbalance and trip. This is something to check from time to time. GFCI Installation Since a GFCI senses the difference in current between the Hot and Neutral circuits legs, it is important that the GFCI be directly connected to the AC source which in most cases is the circuit breaker panel. The shortest path is the GFCI that mounts in the breaker panel but is not the most convenient. A GFCI should never be added as an extension of an existing circuit since the upstream circuit (the one you are extending) could have a current imbalance that the GFCI would sense but not protect. You can add outlets to a GFCI and the GFCI will protect the downstream circuits. There are screws specifically marked as Line and Load. The Line connections are to the AC source. The Load connections are to the extension circuits. What to do if the GFCI trips? A tripping GFCI is an indication of a current leakage problem. If the GFCI is tripping, find the leakage. This is very important because you could become part of the leakage path and that leakage current could kill you. Where to use GFCIs? GFCIs should be used on any circuit where you can easily become part of the leakage path. Outside circuits and circuits in wet areas like the kitchen and bathroom are the most obvious. If you can connect a new circuit to the source, there is not reason not to use a GFCI instead of a regular electrical outlet.

Disclaimer: The information in this site is a collection of data we derived from the vendors and from our personal experiences. This information is meant as a learning guide for you to make your own decisions Best practices and code should always be followed. The recommendations we make are from our personal experiences and we do not receive any compensation for those recommendations.

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