FAQ:Whats the Difference Between GFCI and Circuit Breakers

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FAQ:Whats the Difference Between GFCI and Circuit Breakers

Postby bdosborn » Sun Sep 24, 2006 12:25 pm

This topic seems to come up a lot. Here's the differences:

-Ground Fault Circuit Interrupters

A GFCI receptacle monitors the amount of current going out on the hot wire and the amount returning on the neutral. A difference of 0.005 amps or greater will cause the receptacle to trip. If there's a current difference between the hot and neutral it means that current is going somewhere it shouldn't, like through you to ground. It also trips so fast that you might not even feel anything if you are being shocked. GFCI is specifically for personnel protection against being electrocuted. GFCI is available integral with circuit breakers so its possible to combine the two and not have to use GFCI receptacles.

-Fuses/Circuit Breakers

I like circuit breakers so I'll just talk about those. Fuses can be considered essentially the same thing for our purposes. Circuit breakers are for protection against over current conditions. An over current occurs for two reasons: you've plugged in too many things (or too large a device) and from short circuits. Current flowing through a wire causes it to heat up. If it heats up too much the insulation will melt and/or burn. Most of our trailers use a single 20A, 120V circuit to power all the AC devices. A #12 wire will safely carry 20A forever. If for some reason the wire is carrying too much current (for the reasons shown above) we want something to turn off the power. Thats what a circuit breaker does. A circuit breaker is to prevent damage to wiring and to prevent fires from overheated wires. It serves a different purpose than GFCI

But campgrounds all have circuit breakers, you say. Why do I need one in my trailer? Because a lot campgrounds have crappy equipment thats old and is never tested. You don't want to rely on someone elses crappy stuff to protect your trailer from burning up. Also, a lot of campgrounds only have 30A receptacles that require an adapter for us to use our 20A plugs. We need a circuit breaker to make sure we don't draw more than 20A.

So which one do I use? Use BOTH. The GFCI and circuit breakers provide different kinds of protection and compliment each other.

Hope this helps,
Bruce
P.S. An equipment ground is not required for a GFCI to work but should be provided for safety reasons. That could be another topic...
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Postby apratt » Sun Sep 24, 2006 12:45 pm

Bruce what are your thoughts on gfci circuit breakers.
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Postby bdosborn » Sun Sep 24, 2006 12:59 pm

Functionally they are the same as an outlet but they're kind of spendy and take up two poles instead of one. Also, GFCI can be burned out by voltage spikes which is why they have a test button. I'd rather replace an outlet than a spendy circuit breaker.
Bruce
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Postby kayakrguy » Wed Nov 22, 2006 8:44 am

Bruce,

Thanks for your post...simple, clear, and life and property saving! :applause: :thumbsup: :applause: :thumbsup: :applause: :thumbsup:

Jim
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Postby bdosborn » Thu Nov 23, 2006 1:38 pm

Its my pleasure. I can post more electrical FAQs if you have any questions.
Bruce
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