Is it ok to wire 2 or more GFCIs in series?

orourkeAugust 30, 2008

I have one receptacle string in my house where two GFCIs are wired, in series. Is that a problem?

In theory two in series should provide at least as much protection as having just on on the first receptacle in the string. But is there a chance that the two could somehow "synchronize/resonate" and end up not tripping or significantly delaying power shutoff?

Why do I have two GFCIs in a string and not just one on the first receptacle in the string? Because previous owner had already put a GFCI in the bathroom - which is somewhere midway in the string - and yesterday when I put GFCIs in the 1st receptacle of every string I saw no reason to bother reverting the bathroom GFCI to a regular receptacle.

BTW, I tested the protection at every receptacle by taking some current from the hot(black) wire and routing it through a 25W light bulb to the neutral(white) of another circuit to create an actual leakage. I noticed that for those receptacles that are after both GFCIs, both GFCIs tripped when I tested with the light bulb.

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Not a problem with doing this. However the one that will trip may not be the one closest to the fault.

    Bookmark   August 30, 2008 at 3:19PM
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Yep, and your test demonstrated the biggest problem with this approach: potential for confusion. When a GFCI trips, which outlet had the problem? Which GFCI tripped? Or worse, which combination of GFCI(s)?

GFI receptacle manufacturers must love it. How many times have we seen posts in this forum that begin something like this:

My [garage/bathroom/basement/take your pick] GFI outlet tripped and I tried resetting it. I couldn't get it to work so I went to Home Depot and bought a new one. The new one doesn't work either. Why is my outlet still dead?

If I'm putting more than one GFI outlet on the same circuit (and there are some cases where that makes sense), I prefer to avoid wiring to the second one to the load side of the first one wherever feasible.

    Bookmark   August 30, 2008 at 4:51PM
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why not just take the original 1st outlet and put it where the 2nd GFCI is now?

    Bookmark   August 30, 2008 at 6:13PM
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Or feed the hot line to the "line" terminals of both GFCI receptacles.

That way they are not actually in series.

    Bookmark   August 31, 2008 at 9:28AM
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I wasted two hours today trying to replace 2 reg outlets with 2 gfci's. The 2 outlets are on either side of the sink and then the circuit continues on to another outlet and then the microwave. There's a 20 A breaker at the board so I bought 20 amp gfci's. I wired them in the holes for behind wiring and could nor get them to work no matter how I wired them. What am I missing?

    Bookmark   February 15, 2011 at 8:28PM
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