# MWBC Electrical Circuit issue



## layne (Jul 18, 2013)

Wondering if we have any electricians in the house?
My issue is that I have a multiwire branch circuit (MWBC) running to the home theater room, one circuit goes to a small sink and is GFCI protected, the other circuit goes to the equipment area. The GFCI is the first outlet on the first circuit, when I test the GFCI it cuts off power to the downstream outlets in the HT but the GFCI outlet itself stays hot.

I can't figure out how the GFCI is staying hot while opening the switch to all downstream outlets?
I'm sure it has something to do with the MWBC and the shared common but I can't figure out what that is and was hoping someone might have an idea.

Thanks


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## stereo2.0 (Sep 25, 2009)

I don't think it's a multi-wire branch circuit problem at all. It sounds like the GFCI was wired backwards by mistake. (*DANGEROUS!!!*)

A GFCI should have a pair of contacts on the back labelled "input". This is where the "always live" wires from the breaker panel should be connected to.
Once the GFCI test button is pressed the front outlets should lose power.
There is also a pair of contacts on the back labelled "output". Any subsequent outlets wired to this output should also lose power once the test button is pressed.

Sounds like you need an electrician friend to come by and turn off the breaker that controls the GFCI outlet before swapping the wires between the input and output contacts.
That should correct this inherently dangerous situation.


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