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We just had our kitchen remodeled, and 5 new electrical lines were installed:

Line/circuit 1: Room lights and hood

Line/circuit 2: 1st 1/2 of the outlets + 1st GFCI outlet

Line/circuit 3: 2nd 1/2 of the outlets + 2nd GFCI outlet

When we turn the hood on along with the room lights, it trips the breaker to line/circuit 1, even though only 4.7 of the 15 amps is being used. The GFCI outlets also sometimes trip even though they are on separate circuits.

When we turn the hood on without the room lights, it works fine and uses only 0.7 of the 15 amps.

When we plug the hood into the GFCI outlets (Line/circuit 2), it trips circuit 2 AND circuit 1, even though it is not longer connected to circuit 1.

Any ideas? Crossed circuits? Problem with the hood? Other ideas/recommendations?

Thank you!

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  • Is this a multi wire branch circuit? – Ed Beal Sep 1 '17 at 18:22
  • Hi Ed, To be honest, I don't know. I had an electrician complete the work. – user74954 Sep 1 '17 at 20:00
  • Can you post the nameplate for the hood? I'm wondering if the starting spike is causing the trip... – ThreePhaseEel Sep 1 '17 at 22:13
  • Sure... Its a Z-Line KL3-30 wall range hood – user74954 Sep 1 '17 at 22:23
  • How many GFCI outlets are on circuit 2? Does each one have a test/reset button? Did the electrician recommend this or did you request it? – Harper Sep 1 '17 at 23:17
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You either have a short or you are back feeding from another circuit. I'm not sure, but let's start at the Panel. Since you know which breakers are tripping, turn off one circuit breaker and check the load side of the that breaker and see if we are reading a voltage. Try it again in reverse with the other breaker. If you are reading voltage with the breaker in off position then you know you have a phase to phase sort somewhere in the wiring. You simply have to go out and find where they are connected together. By the way use a voltmeter.

I would be looking for a white wire that is being used as a part of a switch leg that is somehow feeding back into a neutral.

If you have no voltage as discussed, then disconnect all equipment and check to see if it is the wiring or a piece of equipment. If it's the equipment, get it replaced. If its the wiring we are back to tracing the wiring out.

What ever you are doing just make sure the power is of before working on it. I would only have the power on when I was looking for voltage.

I am assuming you installed the 5 circuits yourself and are familiar with what was done. If you had an electrician do the work, just call him and have him come back and fix his problem.

Good luck and stay safe.

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  • Thank you very much, RME. Very helpful. When you say "a white wire that is being used as part of a switch leg that is somehow feeding back into neutral," what do you mean? I know more than the average consumer about electrical circuits, but my knowledge is still pretty limited! – user74954 Sep 1 '17 at 20:22
  • Also... What do you mean by "Try it again in reverse with the other breaker" ? Thank you! – user74954 Sep 1 '17 at 22:24
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    He is basically saying turn breaker 1 off, use a meter and read hot & neutral of the LOAD side of the circuit to circuit breaker #1. In other words, when the breaker is off, there should be 0VAC read on the hot line coming off the breaker. Then, Turn on Breaker1, turn off Breaker 2, test again, but read for 0VAC on breaker 2's output – noybman Sep 2 '17 at 0:38
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GFCI's and AFCI's both want to see the exact same amount of current going down the hot line as coming back on its partner neutral line. This method of detection absolutely depends on the hots and neutrals in any circuit being faithfully monogamous with each other.

GFCIs don't look at ground at all. So all the grounds can intertwine (as long as they come out of the same service panel).

So if circuit 1 is tripping GFCI or AFCI on circuit 2, the meaning is plain: something on circuit 1 is bootlegging off a hot or neutral from circuit 2. If circuit 1 also had an AFCI or GFCI, that may also trip, if the bootleg is downstream (i.e. in the area of wiring protected by the device).

It may not be the electrician's mistake. Back before GFCI, you were supposed to keep hots and neutrals monogamous for a simple reason: neutrals don't have circuit breakers, and the only thing that keeps a neutral from overloading is the breaker on the partner hot. If neutrals got shared, they could overload. But the system never enforced it, so if someone grabbed the wrong hot or neutral, you would've never known.

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What it sounds like is that you have a crossed neutral somewhere.

Perhaps the GFCI's were not wired correctly.

They might have done something like connect hot and ground for you Hood Fan and skipped out on the Neutral. While Neutral and Ground are 'basically' the same - they are NOT.

You do not mention if the Circuit Breakers were new or not - are any of those Arc protected breakers ? [Arc Fault CI].

EDIT 9-2-2017

Based on what you have commented I am adding this: What it sounds like is that there is a crossed up neutral or crossed up GFCI circuit. Given you have two GFCI receptacles, they are probably wired up down stream one from the other. These units have a special connection Line In and Line Out - verify that this is not only correct Line In and Line out (to down stream) but also make sure that your L1 and Neutral are properly connected to the GFCI on both Receptacles.

While I suspect the GFCI .. As for your Range hood - make sure your hot, neutral and ground are wired appropriately. In the USA it is most likely 120V, Black is hot, white is neutral and green is ground.

EDIT 9-2-2017 Some wiring images for GFCI receptacles:

GFCI with protected downstream outlets. GFCI protected downstream outlets

GFCI to GFCI to Load.

GFCI to GFCI to Load

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  • Thank you, Ken. Yes... The circuit breakers were just installed. I think they are Arc protected. – user74954 Sep 1 '17 at 19:53
  • @user74954 Your Arc protection Circuit breakers can be very finicky. The Hood I am amazed the motor runs and the lights trip the circuit (LED lights maybe or are they halogen?) ,Normally a motor could kick out the Arc fault interrupter. You might try to add an isolation transformer between the range hood and the power line. However I think there is something else going on here considering your GFCI circuits trip both breakers. I am going to add something to my answer. – Ken Sep 2 '17 at 7:07
  • They are LED lights. The electrician said he wanted to Che he the transformer in the hood to possibly fix the problem. It sounds like you are saying this would likely not actually fix the underlying problem. Am I understanding you correctly? – user74954 Sep 2 '17 at 19:31
  • @user74954 LED lights are frequency controlled power which could interfere with the ACFI but should not affect the GFCI.when I mentioned Transformer I was talking about installing an Isolation Transformer. it is basically a 1 to 1 xformer. 120 in 120 out. I am still thinking that something is not wired correctly - double check GFCI - the instructions and labels on GFCI receptacles are quite simple to see how it is to be connected. I will attach some images.. – Ken Sep 2 '17 at 22:59

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