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Oak Park, IL
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Linn, OR
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 Multiple GFCIs
[#2] Posted: 06/20/2008 - 12:29:53 PM |  |  |
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Looking at the circuit diagrams of a few GFCI's, I can't see where installing a GFCI breaker and then an additional GFCI outlet on the same circuit would keep one of the GFCI's from protecting you. Circuit Diagram...
http://www.rhtubs.com/GFCI/gfc...cuit.gif
Although there may be other circuit designs out there which might not work when they are mixed or one used with another??? I don't know.
GFCI's work by detecting an "imbalance" in the electricity used in both the hot and neutral. If everything is normal, the flow of electricity through the hot equals the same flow in the neutral. If you are being electrocuted, some electricity would be flowing through your body and the GFCI would notice more electricity was flowing through one wire and not coming back through the other. Then this would cause the GFCI to trip. (By creating an electric current in the donut shaped ring in the above diagram.)
To me this situation is like having two circuit breakers on the same circuit. Or like a power strip with a breaker plugged into a circuit which has a breaker.
Then there is the case of a hair dryer which has its own GFCI in the plug. In that case you would also have two GFCI's - one plugged into the other if the bathroom has a GFCI outlet. More on this...
http://home.howstuffworks.com/...yer4.htm
I would not install a GFCI breaker then a GFCI outlet on the same circuit just because it would cost more and is not needed. Waste of money!
And then I would see an issue of "confusion" in that there are two GFCI's and a homeowner not knowing clearly what to reset should one or the other trip.
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Evanston, Illinois
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Multiple GFCIs
[#3] Posted: 06/20/2008 - 1:11:45 PM | | |
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I spoke with an electrician about these scenarios a few years ago, and he agreed with you billy bob.
I have found that when I check the GFCI's receptacles that are either wired into a GFCI breaker, or downstream of other GFCI's the confusion factor comes into play. Sometimes it trip here, sometimes it trips there. I usually just make a note of it in the report sighting the confusion factor but not as a safety hazard. I let 'em know that if they want to call an electrician to clean up the confusion they can.
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Oak Park, IL
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Multiple GFCIs
[#4] Posted: 06/20/2008 - 1:49:21 PM | | |
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Thanks for the help. I'll note the confusion factor only.
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Rick Sabatino
Sabatino Consulting, Inc |
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Severna Park, Maryland
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Multiple GFCIs
[#5] Posted: 06/20/2008 - 2:47:43 PM | | |
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A few months ago I had an inspection that had garage receptacle which was protected by a GFCI in main bathroom. That GFCI was fed by another GFCI in the master bathroom. When I tripped the receptacle in the garage with my tester it tripped both GFCI's.
You can feed from a GFCI without being protected by it. This is done by wiring to the "line" terminal instead of the "load" terminal.
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John Dirks Jr - Arundel Home Inspection LLC - MD license: 29827
Maryland Home Inspectors - Maryland Home Inspection - Maryland Radon Testing - Baltimore County Rental Inspection
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Linn, OR
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Multiple GFCIs
[#6] Posted: 06/20/2008 - 8:36:13 PM | | |
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When a GFCI trips, it activates an electrically powered mechanical switch to turn off the power (with the models I have seen).
So some GFCI's could be slightly faster than others and in that case only one would trip. (Once one GFCI has tripped, the "fault" and/or power would have been removed from the line. If the mechanical arm on the other GFCI was in the process of moving to trip, it would no longer have power to continue moving and might not finish its "trip" motion.)
Both of your GFCI's were exactly the same speed! (A race!)
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Orient, Ohio
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Multiple GFCIs
[#7] Posted: 06/20/2008 - 9:37:39 PM | | |
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"The breaker has 4 wires connected to it. Each heads out a different conduit run. Two of these go to the exterior outlets. The other two go to the upstair bathrooms where they are connected to GFCI outlets. "
I've seen breakers that allow two wires to be connected but NEVER four wires. Isn't that alone a reason to make safety improvements??
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| David A. Inspecting Columbus, Ohio |
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Evanston, IL
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Lexington, KY
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Virginia Beach, VA
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Oak Park, IL
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Multiple GFCIs
[#11] Posted: 06/27/2008 - 09:41:31 AM | | |
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Thanks to all that replied.
Yes. Conduit is required here. I did write up the quadruple lugging and suggested separating the circuits, there is room in the box. I was just unclear about multiple GFCI's on the same circuit. I was not sure they would function properly.
Thanks for all the help.
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Rick Sabatino
Sabatino Consulting, Inc |
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