Two GFIs on One Circuit

[sk5223]

One of the shows on HGTV (gulp) had an electrical "expert” say that having two Ground Fault Interrupters (GFIs) on the same circuit would cause them to be ineffective because they would cancel each other out. Is that really true?

Why would I want to do that in the first place, you ask? This is for an outdoor receptacle close to a pond. So one GFI would be at the panel, built in to the breaker, in order to protect the entire line. The second would be at the receptacle providing a convenient switch.

First post . . . please be gentle.

 

[dittle fart around]

Eliminate the ground fault breaker, otherwise what you think is a handy switch by the pond would require you to go back to the breaker. A ground fault device protects everything on the circuit past the device. If there are more outlets closer to the house on the same circuit they wouldn't be protected by the pond ground fault outlet.

 

[sk5223]

Many thanks.

 

[ripperd]

Also, I think the TEST function you want to use as a switch actually causes a ground fault. You might trip the breaker box gfci if it is more sensitive than the outside box when you hit TEST!

 

[sk5223]

Yes, quite right, Ripperd.

I think that was the point that "dittle fart around" was making, too.

Advice much appreciated.

 

[wyliesdiesels]

Not only is it a bad idea to have one GFCI feeding another due to possible conflict between the 2, its a waste of money.

 

[67carl]

Just for my education - if he wanted to have a GFI near the pond so he could reset it there (convenience) and have another GFI on the same circuit, earlier in the run, say in the garage, couldn't he do what's in the pic below and everything would function as it's supposed to? I understand it's not necessary and adds extra cost, but for convenience?

 

[C96]

The test button on GFCI receptacles are not meant to be used as a switch.

Remove the GFCI receptacle at the pond and install a switch for on/off operation.

Your circuit is already protected by the GFCI breaker at the panel.

 

[teamextreme]

All good advice above. Regarding the HGTV expert, he's clearly not. 2 GFI's is not necessary, a waste of money and can cause nuisance tripping, but they certainly don't cancel each other out and not work.

Coincidentally, I just did some poking around the garage in my newly purchased house and found the PO had installed 2 GFI receps feeding each other. Hitting the test button on the downstream one tripped both. I'll be removing one of them soon.

 

[foodgroup]

Just for my education - if he wanted to have a GFI near the pond so he could reset it there (convenience) and have another GFI on the same circuit, earlier in the run, say in the garage, couldn't he do what's in the pic below and everything would function as it's supposed to? I understand it's not necessary and adds extra cost, but for convenience?

I wired my kitchen countertops like that, 4 independent GFCI receptacles on 2 different circuits, so any one can trip without affecting the others and you don't need to know how the kitchen is wired to reset them.

They were only about $12/each and have indicator lights so you can tell that the outlet is live, I like them very much.

 

[lbmcse]

The notion that multiple GFCI's on a circuit causes tripping is nonsense. They work independently, and one is not affected by the other--except that any tripped GFCI will shut down everything downstream of it. That said; there is no good reason to have a GFCI receptacle downstream of another. Any GFCI receptacle fed by one is already GFCI protected. You'd have redundancy, but this redundancy doesn't cause nuisance tripping.

As for putting a GFCI receptacle on a circuit already protected with a GFCI breaker, this is also wasteful.

GFCI redundancy is a wasteful. Either use a GFCI breaker with non-GFCI receptacles; or a standard breaker, with the first receptacle on the circuit a GFCI, and feed non-GFCI receptacles from that. Every receptacle downstream is protected.

You wouldn't put a vault inside a vault, would you?

 

[Aquamoose]

FYI, you could wire / install more than one GFI's on the same branch provided that the first is NOT protecting downstream. Kinda like one branch to provide two rooms, each with its own GFI's. The first GFI can protect just the standard outlets in the first room only and the 2nd room circuit would branch FROM that first GFI (tapping the hot before the GFI), feeds to the second GFI in the second room and therein, protects standard outlets in that room.


Sent from my iPhone using Tapatalk

 

[Gooch]

The notion that multiple GFCI's on a circuit causes tripping is nonsense. They work independently, and one is not affected by the other--except that any tripped GFCI will shut down everything downstream of it. That said; there is no good reason to have a GFCI receptacle downstream of another. Any GFCI receptacle fed by one is already GFCI protected. You'd have redundancy, but this redundancy doesn't cause nuisance tripping.

Yes. It can cause nuisance tripping. There was a thread a few weeks ago where someone had that exact problem.

 

[BFBOB]

Maybe we're not using the term "nuisance trip" the same? I would consider a nuisance trip one where no ground fault exists but the GFI trips anyway. I very much doubt that having two GFI's on one circuit with one on the Load side of the other would cause this.
On the other hand, having one GFI "protected" by another could very well cause both to trip if either senses a ground fault. I still would not consider that a "nuisance trip"; there really was a ground fault. But, it would certainly be inconvenient to have to reset both GFI's (and in the right order!) to restore power.

The correct answer to OP's question has already been given. Leave the GFI breaker in place, eliminate the far end GFI outlet, install a proper switch at the far end.

 

[Gooch]

Maybe we're not using the term "nuisance trip" the same? I would consider a nuisance trip one where no ground fault exists but the GFI trips anyway. I very much doubt that having two GFI's on one circuit with one on the Load side of the other would cause this.
On the other hand, having one GFI "protected" by another could very well cause both to trip if either senses a ground fault. I still would not consider that a "nuisance trip"; there really was a ground fault. But, it would certainly be inconvenient to have to reset both GFI's (and in the right order!) to restore power.

The correct answer to OP's question has already been given. Leave the GFI breaker in place, eliminate the far end GFI outlet, install a proper switch at the far end.

Nope, we both understand nuisance tripping. the problem was the HO had GFCI breaker and a GFCI recp. at the POU, when anything was plugged in it would trip the breaker. I've come across this at work repeatedly aswell, not all breakers will do this with all receps. but some combonations will cause them to trip when there is no issue.

 

[bmbsqd]

I wired a small garage at my old house with 5 GFI's. I did not want any trip to take out the rest of the outlets. My breaker box was an old Pushmatic so using GFI breakers was out of the question. As long as you don't wire one GFI to the load terminals of another there should be no problems. I never had any issues with nuisance trips. Bear in mind that they do get old and stop functioning correctly and that can be the cause of the nuisance trips. I replaced one in a different house that kept tripping with only a 2 bulb strip light plugged into it. No more trips with a new GFI.

 

[msgross]

Your GFI probably came with instructions on how many regular outlets it could protect, for some reason the #6 comes to mind for the last one I installed. I guess if you had 10 outlets on a circuit then #1 and #7 or #8 would need to be GFI's in that case...

I do know that my outside outlets are protected by the bathroom GFI and it was a PITA to figure out when it tripped. Would have been nice to simply reset it at the location.