GFCI trips when toaster oven turned on

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VaR
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GFCI trips when toaster oven turned on

Post by VaR » Mon May 28, 2018 12:40 pm

I have had an odd situation over the past few years and no one I've talked to has come up with a diagnosis.

I have a toaster oven plugged into an outlet on the island in my kitchen. When I turn it on, the GFCI trips over by the sink. But the outlets on the island continue to work, so the island outlets aren't "downstream" from the GFCI. No other items plugged into this outlet will trip the GFCI.

What could be causing this and what should I do about it?

The most perplexing thing is that this outlet isn't downstream from the GFCI, yet is tripping it. I've never heard of this before.

Thanks in advance!
Last edited by VaR on Mon May 28, 2018 1:09 pm, edited 1 time in total.

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Re: GFCI trips when toast oven turned on

Post by indexfundfan » Mon May 28, 2018 12:43 pm

How do you know for certain the outlet is not downstream from the GFCI? Have you tested it with a receptacle tester?
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Re: GFCI trips when toast oven turned on

Post by adamthesmythe » Mon May 28, 2018 12:54 pm

It may be advisable to get a new toaster.

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Re: GFCI trips when toast oven turned on

Post by sport » Mon May 28, 2018 12:56 pm

When the toaster trips the GFI, does the toaster continue to operate with the GFI tripped?
If not, that particular outlet is downstream from the GFI even if others are not.

VaR
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Re: GFCI trips when toast oven turned on

Post by VaR » Mon May 28, 2018 1:09 pm

sport wrote:
Mon May 28, 2018 12:56 pm
When the toaster trips the GFI, does the toaster continue to operate with the GFI tripped?
If not, that particular outlet is downstream from the GFI even if others are not.
Yes, the toaster continues to toast after the GFCI is tripped. I'm using that to assume that the island outlet is not downstream from the GFCI.

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Re: GFCI trips when toast oven turned on

Post by cadreamer2015 » Mon May 28, 2018 1:10 pm

Even if the toaster plugs are upstream of the GFCI, is it on the same circuit? (Check the breaker box). If it is on the same circuit, perhaps the CFCI is detecting some anomaly in the current/voltage when the toaster is turned on. But IANAE. I would look into replacing the toaster as well.
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The Wizard
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Re: GFCI trips when toast oven turned on

Post by The Wizard » Mon May 28, 2018 1:11 pm

Two separate problems:

I assume your toaster oven has a three prong plug with ground. So there's some sort of crack around the heating element which allows a small amount of current to leak to the metal body of the oven which is grounded, hence tripping the GFCI.

The issue of the other outlets is merely a wiring issue. When properly wired, outlets downstream will turn off also. When improperly wired, they won't...
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Re: GFCI trips when toast oven turned on

Post by The Wizard » Mon May 28, 2018 1:19 pm

VaR wrote:
Mon May 28, 2018 1:09 pm
sport wrote:
Mon May 28, 2018 12:56 pm
When the toaster trips the GFI, does the toaster continue to operate with the GFI tripped?
If not, that particular outlet is downstream from the GFI even if others are not.
Yes, the toaster continues to toast after the GFCI is tripped. I'm using that to assume that the island outlet is not downstream from the GFCI.
Very unusual situation.
This means the toaster oven outlet is miswired and not downstream from the GFCI.
Experiment by moving the oven to all the other outlets and you'll see it shut off when GFCI trips...

Note: all kitchen outlets should be GFCI protected...
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Re: GFCI trips when toast oven turned on

Post by dumbmoney » Mon May 28, 2018 1:34 pm

What outlets do lose power when the GFCI trips (use the test button on the GFCI)?
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Re: GFCI trips when toast oven turned on

Post by The Wizard » Mon May 28, 2018 1:37 pm

dumbmoney wrote:
Mon May 28, 2018 1:34 pm
What outlets do lose power when the GFCI trips (use the test button on the GFCI)?
That will ID the outlets downstream from the GFCI.
The original oven outlet, clearly, is upstream...
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Re: GFCI trips when toast oven turned on

Post by neilpilot » Mon May 28, 2018 1:37 pm

The Wizard wrote:
Mon May 28, 2018 1:19 pm

Very unusual situation.
This means the toaster oven outlet is miswired and not downstream from the GFCI.
Experiment by moving the oven to all the other outlets and you'll see it shut off when GFCI trips...

Note: all kitchen outlets should be GFCI protected...
All kitchen COUNTERTOP outlets should be GFCI protected. As an example, we have several outlets along the wall that are not GFCI. In fact, most kitchens would include a refrigerator outlet that in my opinion should definitely NOT be GFCI, unless you want to risk food spoilage on a compressor restart.
Last edited by neilpilot on Mon May 28, 2018 1:39 pm, edited 1 time in total.

VaR
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Re: GFCI trips when toast oven turned on

Post by VaR » Mon May 28, 2018 1:38 pm

The Wizard wrote:
Mon May 28, 2018 1:19 pm
Very unusual situation.
I agree!
This means the toaster oven outlet is miswired and not downstream from the GFCI.
You mean under the 2014 NEC, right? I'm pretty sure that under whatever version of the NEC that was in force back in 1987, you were only required to GFCI protect outlets that were under a certain distance from the sink. But that's not what I'm asking. :)
Experiment by moving the oven to all the other outlets and you'll see it shut off when GFCI trips...
I used my GFCI tester and verified that only the outlets by the sink are GFCI protected.
Note: all kitchen outlets should be GFCI protected...
I agree in general principle and in fact for all kitchens brought up to current NEC code.

Another information point: When I plugged my GFCI tester into the troublesome GFCI outlet, it tripped - even before hitting the "test" button. This doesn't happen with my other GFCI outlets.

I wonder if I just have a bad GFCI outlet and need to replace it? It still doesn't explain to me why turning on the toaster trips the unrelated GFCI.

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Re: GFCI trips when toast oven turned on

Post by dumbmoney » Mon May 28, 2018 1:54 pm

VaR wrote:
Mon May 28, 2018 1:38 pm
Another information point: When I plugged my GFCI tester into the troublesome GFCI outlet, it tripped - even before hitting the "test" button. This doesn't happen with my other GFCI outlets.

I wonder if I just have a bad GFCI outlet and need to replace it? It still doesn't explain to me why turning on the toaster trips the unrelated GFCI.
Yeah, replace it.
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Re: GFCI trips when toast oven turned on

Post by GW208 » Mon May 28, 2018 2:12 pm

VaR wrote:
Mon May 28, 2018 1:09 pm
sport wrote:
Mon May 28, 2018 12:56 pm
When the toaster trips the GFI, does the toaster continue to operate with the GFI tripped?
If not, that particular outlet is downstream from the GFI even if others are not.
Yes, the toaster continues to toast after the GFCI is tripped. I'm using that to assume that the island outlet is not downstream from the GFCI.
The GFCI has line and load terminals. The hot wires from the breaker panel go to the line terminals, the wires feeding the outlet on the island should be connected to the load terminals. I'll bet that both sets of wires are connected to the line terminals.

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Re: GFCI trips when toaster oven turned on

Post by whodidntante » Mon May 28, 2018 3:20 pm

GFCI outlets are cheap and easy to replace.

VaR
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Re: GFCI trips when toast oven turned on

Post by VaR » Mon May 28, 2018 3:42 pm

The Wizard wrote:
Mon May 28, 2018 1:11 pm
I assume your toaster oven has a three prong plug with ground. So there's some sort of crack around the heating element which allows a small amount of current to leak to the metal body of the oven which is grounded, hence tripping the GFCI.
I should have mentioned that there's nothing wrong with the toaster. It doesn't trip a GFCI outlet when it is actually plugged into it.
The issue of the other outlets is merely a wiring issue. When properly wired, outlets downstream will turn off also. When improperly wired, they won't...
The outlets are upstream from the GFCI, not downstream.

And yes, I understand that this 1987 kitchen is not up to 2011/2014 NEC, but rewiring my kitchen to bring it up to code is something I was going to take care of if I ever remodel the kitchen.
dumbmoney wrote:
Mon May 28, 2018 1:34 pm
What outlets do lose power when the GFCI trips (use the test button on the GFCI)?
None, just the GFCI outlet itself. The same goes for the GFCI outlet on the other side of the sink.
GW208 wrote:
Mon May 28, 2018 2:12 pm
The GFCI has line and load terminals. The hot wires from the breaker panel go to the line terminals, the wires feeding the outlet on the island should be connected to the load terminals. I'll bet that both sets of wires are connected to the line terminals.
I'm a little hesitant to turn a whole set of wiring into the downstream of a GFCI in an old house. Never can tell what's on the rest of the circuit. For instance, it surprised me that the (wired) kitchen smoke alarm was on the same circuit as the bedroom outlets.

I'm guess I'll never figure out exactly what was happening and I'll just replace the GFCI outlet. I guess I may as well replace the island outlets with GFCI outlets since (as per above) I don't want to risk putting the whole downstream circuit onto the GFCI. But perhaps I'm being too conservative?

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Re: GFCI trips when toaster oven turned on

Post by rustymutt » Mon May 28, 2018 7:40 pm

Your toaster is ....well, toast. LOL The other outlet may be on another GFCI Breaker. My kitchen island is on different GFCI circuist.
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Re: GFCI trips when toast oven turned on

Post by CurlyDave » Tue May 29, 2018 12:23 am

The Wizard wrote:
Mon May 28, 2018 1:19 pm

...Very unusual situation.
This means the toaster oven outlet is miswired and not downstream from the GFCI.
Experiment by moving the oven to all the other outlets and you'll see it shut off when GFCI trips...

Note: all kitchen outlets should be GFCI protected...
I would very strongly recommend that you go down to Home Depot and get a receptacle tester (less than $10) instead of using the toaster oven in that way. Get a tester with a button that you can push to trip the GFCI.

Test every outlet in the kitchen. Push the button the the tester for every single one and be certain they go off. This is a safety issue.

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Re: GFCI trips when toaster oven turned on

Post by DavidW » Tue May 29, 2018 12:46 am

I am very leary of countertop appliances. I have read that some home have been burned down because those appliance shorted and caused a fire. For that reason, I use a wall timer (https://www.amazon.com/BELKIN-F7C009q-C ... wall+timer) so that I can only have the toaster set for 30 minutes (30 min, 3 hrs or 6 hrs) before there is no power going to the device.

I know some people unplug their devices but that is too much of a hassle for me.

I also have this for the home printer/copier/fax. I found that these multi function deices use 40+ watts even in sleep mode. It don't sound like much but it comes to close to 1 kw per day and 30 kw /month... That is about $9-$10/month just to have the printer ready all hours of the day...

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Re: GFCI trips when toast oven turned on

Post by inbox788 » Tue May 29, 2018 6:40 am

CurlyDave wrote:
Tue May 29, 2018 12:23 am
I would very strongly recommend that you go down to Home Depot and get a receptacle tester (less than $10) instead of using the toaster oven in that way. Get a tester with a button that you can push to trip the GFCI.

Test every outlet in the kitchen. Push the button the the tester for every single one and be certain they go off. This is a safety issue.
Yes, get one of these and test all the outlets. https://www.homedepot.com/p/Pro-sKit-GC ... /206303237

I'm guessing the toaster is causing some current leakage.

Does the toaster trip the GFCI if plugged directly into the outlet? What about known downstream outlets?

The tester should also trip the GFCI if plugged into the outlet that the toaster is currently plugged into.
cadreamer2015 wrote:
Mon May 28, 2018 1:10 pm
Even if the toaster plugs are upstream of the GFCI, is it on the same circuit? (Check the breaker box). If it is on the same circuit, perhaps the CFCI is detecting some anomaly in the current/voltage when the toaster is turned on. But IANAE. I would look into replacing the toaster as well.
Based on what's happening, I would assume the toaster plug is upstream of the GFCI.

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Re: GFCI trips when toaster oven turned on

Post by neilpilot » Tue May 29, 2018 8:27 am

DavidW wrote:
Tue May 29, 2018 12:46 am
I am very leary of countertop appliances. I have read that some home have been burned down because those appliance shorted and caused a fire. For that reason, I use a wall timer (https://www.amazon.com/BELKIN-F7C009q-C ... wall+timer) so that I can only have the toaster set for 30 minutes (30 min, 3 hrs or 6 hrs) before there is no power going to the device.

I know some people unplug their devices but that is too much of a hassle for me.

I also have this for the home printer/copier/fax. I found that these multi function deices use 40+ watts even in sleep mode. It don't sound like much but it comes to close to 1 kw per day and 30 kw /month... That is about $9-$10/month just to have the printer ready all hours of the day...
The Belkin device highlighted above is also idea for limiting the time your phone is on charge overnight. Note that while Amazon's price using the above link is $24, Homedepot & Walmart lists the same unit for under $14.

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Re: GFCI trips when toaster oven turned on

Post by lthenderson » Tue May 29, 2018 11:35 am

Lots of bad advice on here. GFCI's only last about ten years before failing. Most fail by not delivering power downstream. Some fail but still deliver power to downstream which I think is the situation you have here. GFCI's manufactured post 2006 will show you that they have failed. Those manufactured prior to 2006 may not.

The best way to test failure is to buy a GFCI tester that plugs into the GFCI socket that keeps tripping. The cheapest solution is simply to replace it especially if it is more than ten years old.

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Re: GFCI trips when toaster oven turned on

Post by The Wizard » Tue May 29, 2018 11:50 am

lthenderson wrote:
Tue May 29, 2018 11:35 am
Lots of bad advice on here. GFCI's only last about ten years before failing. Most fail by not delivering power downstream. Some fail but still deliver power to downstream which I think is the situation you have here. GFCI's manufactured post 2006 will show you that they have failed. Those manufactured prior to 2006 may not.

The best way to test failure is to buy a GFCI tester that plugs into the GFCI socket that keeps tripping. The cheapest solution is simply to replace it especially if it is more than ten years old.
I'm not sure about that.
I have three or four GFCI protected branch circuits in my garage/workshop that are still working fine thirty years after I installed them.
All sorts of things can go defective over time, but I prefer to identify the problem first and then fix it.
That GFCI tester sounds like the right idea...
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Re: GFCI trips when toaster oven turned on

Post by lthenderson » Tue May 29, 2018 11:58 am

The Wizard wrote:
Tue May 29, 2018 11:50 am
lthenderson wrote:
Tue May 29, 2018 11:35 am
Lots of bad advice on here. GFCI's only last about ten years before failing. Most fail by not delivering power downstream. Some fail but still deliver power to downstream which I think is the situation you have here. GFCI's manufactured post 2006 will show you that they have failed. Those manufactured prior to 2006 may not.

The best way to test failure is to buy a GFCI tester that plugs into the GFCI socket that keeps tripping. The cheapest solution is simply to replace it especially if it is more than ten years old.
I'm not sure about that.
I have three or four GFCI protected branch circuits in my garage/workshop that are still working fine thirty years after I installed them.
All sorts of things can go defective over time, but I prefer to identify the problem first and then fix it.
That GFCI tester sounds like the right idea...
Like anything, it depends on quality of the brand, loads, etc. I've seen some fail as soon as five years and others still going strong 25 years later. But on average 10 years is what is considered normal.

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Re: GFCI trips when toaster oven turned on

Post by celia » Tue May 29, 2018 12:09 pm

Appliances that heat and cool use more electricity than other fixtures. The major appliances that heat and cool are supposed to be on their own circuit, according to manufacturer (and often building code) requirements. These appliances include refrigerator, oven, cooktop, dishwasher, microwave, washer, dryer and maybe the garbage disposal. Putting something else on the same circuit can trip the circuit.
VaR wrote:
Mon May 28, 2018 12:40 pm
I have a toaster oven plugged into an outlet on the island in my kitchen. When I turn it on, the GFCI trips over by the sink. But the outlets on the island continue to work, so the island outlets aren't "downstream" from the GFCI. No other items plugged into this outlet will trip the GFCI.
I don't know what you mean by "downstream", but have you ever mapped which outlets are on each circuit? We made a rough floor plan of our house and located all the outlets and major appliances. Then we turned one circuit off at a time and went around with a small appliance (can opener, tiny lamp) to see all the outlets that were on that circuit and marked the map. (Our circuit box already had the dedicated appliances labeled as to their circuit.) This is best done with 2 or 3 people working together depending on where the circuit box is located.

Specifically, you are looking to see what else is on the same circuit as the outlet where you plug in the toaster oven. Most likely you need to move the toaster oven to a different circuit.

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Re: GFCI trips when toaster oven turned on

Post by Dudley » Tue May 29, 2018 12:12 pm

The neutral for the GFCI is wired to a point that is behind where the neutral for the toaster line is being taken off ? Hence the return current from the toaster flows through GFCI neutral return (but not the through the GFCI live side, hence GFCI is imbalanced and trips but toaster continues to operate).

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Re: GFCI trips when toaster oven turned on

Post by celia » Tue May 29, 2018 12:14 pm

lthenderson wrote:
Tue May 29, 2018 11:35 am
Lots of bad advice on here. GFCI's only last about ten years before failing. Most fail by not delivering power downstream. Some fail but still deliver power to downstream which I think is the situation you have here. GFCI's manufactured post 2006 will show you that they have failed. Those manufactured prior to 2006 may not.

The best way to test failure is to buy a GFCI tester that plugs into the GFCI socket that keeps tripping. The cheapest solution is simply to replace it especially if it is more than ten years old.
That does not locate the "cause" of the problem. I've never heard of GFCIs being the cause, unless they were defective to begin with. But the electrician who installed it would have tested it during installation.

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Re: GFCI trips when toaster oven turned on

Post by lthenderson » Tue May 29, 2018 12:19 pm

celia wrote:
Tue May 29, 2018 12:14 pm
lthenderson wrote:
Tue May 29, 2018 11:35 am
Lots of bad advice on here. GFCI's only last about ten years before failing. Most fail by not delivering power downstream. Some fail but still deliver power to downstream which I think is the situation you have here. GFCI's manufactured post 2006 will show you that they have failed. Those manufactured prior to 2006 may not.

The best way to test failure is to buy a GFCI tester that plugs into the GFCI socket that keeps tripping. The cheapest solution is simply to replace it especially if it is more than ten years old.
That does not locate the "cause" of the problem. I've never heard of GFCIs being the cause, unless they were defective to begin with. But the electrician who installed it would have tested it during installation.
You are assuming there is a problem. I don't think there is a problem other than the GFCI has failed to work properly. Google "GFCI Life Expectancies" and you will find lots of literature talking about failure rates. Modern GFCI's are required by law as of 2006 to not allow a reset once the GFCI stops working properly as a way to combat their failure rates. Pre 2006, anything could happen including the situation presented which is definitely not desirable and why the law was enacted.

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Re: GFCI trips when toaster oven turned on

Post by criticalmass » Tue May 29, 2018 12:22 pm

It's very possible that the GFI is the issue. There are lots of cheap (often Chinese made) GFI outlets out there. I had a cheap one trip when the washer would start to spin. Replace the interrupter and see if that fixes your problem. It is possible that the malfunctioning GFI can't deal with the transient created by your toaster starting.

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Re: GFCI trips when toaster oven turned on

Post by The Wizard » Tue May 29, 2018 12:41 pm

celia wrote:
Tue May 29, 2018 12:14 pm
lthenderson wrote:
Tue May 29, 2018 11:35 am
Lots of bad advice on here. GFCI's only last about ten years before failing. Most fail by not delivering power downstream. Some fail but still deliver power to downstream which I think is the situation you have here. GFCI's manufactured post 2006 will show you that they have failed. Those manufactured prior to 2006 may not.

The best way to test failure is to buy a GFCI tester that plugs into the GFCI socket that keeps tripping. The cheapest solution is simply to replace it especially if it is more than ten years old.
That does not locate the "cause" of the problem. I've never heard of GFCIs being the cause, unless they were defective to begin with. But the electrician who installed it would have tested it during installation.
No. LT is right.
Stuff breaks over time.
I even had one side of my 200 amp main breaker fail 20 years ago...
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Re: GFCI trips when toaster oven turned on

Post by tev9876 » Tue May 29, 2018 12:46 pm

Many electric heating elements use Magnesium Oxide (MgO) ceramic powder as an insulator to prevent the heater wire from contacting the outside metal casing. MgO sucks up moisture like a sponge, so if there is a break in the outer casing it will suck up the moisture and provide a path to ground. It may only be milliamps of current that is leaking, but that is enough to trip a GFCI. If you plug it into a non-GFCI outlet it would probably not be enough for a dead short which would destroy the heater and possibly trip the breaker, so the element just gets hot and bakes out the moisture. With the moisture gone it would work on a GFCI again, until the cycle repeats as the MgO sucks up humidity again. The industrial controllers I used to work on actually had logic built in to slowly ramp up the voltage because of this issue. Putting 240 volts on a cold 5000 watt heater could blow a short through it instantly, so the controller kept voltage low enough to not short out until the heater was above 212 degrees and moisture was evaporated.

Current code also calls for two counter circuits in a kitchen, so it is possible there is another GFI somewhere and you are actually trying two different circuits. It sounds like you might have some other weird wiring going on if your smoke detectors are on with outlets. I'm 99% sure they should be on a dedicated circuit.

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Re: GFCI trips when toaster oven turned on

Post by Dudley » Tue May 29, 2018 2:38 pm

Take the cover off the GFCI. Are there any wire connections to the LOAD side of the GFCI ?

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Re: GFCI trips when toaster oven turned on

Post by BrandonBogle » Tue May 29, 2018 3:00 pm

Dudley wrote:
Tue May 29, 2018 12:12 pm
The neutral for the GFCI is wired to a point that is behind where the neutral for the toaster line is being taken off ? Hence the return current from the toaster flows through GFCI neutral return (but not the through the GFCI live side, hence GFCI is imbalanced and trips but toaster continues to operate).
This is the closest post to my line of thought. The Op could have a faulty GFCI (especially given that a tester trips it without hitting test - though the tester could be bad too). But given the houses age, one option could be a shared neutral across multiple circuits. This could lead to the GFCI-protected outlet(s) being on one circuit, and the toaster on another, but they share a neutral; then imbalanced voltage on the neutral could cause the GFCI to trip.

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Re: GFCI trips when toaster oven turned on

Post by VaR » Wed May 30, 2018 1:11 pm

Thanks everyone for all the ideas and advice.

I replaced the GFCI and that solved the problem. No more odd tripping of the GFCI from the toaster on the "sister" circuit.

Here's some additional info for completeness:
1. I did notice that the electrical box with the GFCI contains two leads - presumably one from the electrical panel and one that goes to island outlets. I need to do some additional circuit tracing but I will put the outgoing circuit on the load line after I assure myself that only the island outlets are served by the outgoing circuit.
2. Note that I do have a standalone circuit and GFCI tester. The island outlets are not GFCI protected and the GFCI tester does not trip the GFCI at the sink. Like I said, I will correct this as soon as I do some circuit tracing.
3. I do know that the island outlets and the sink outlet (GFCI) are all on the same circuit breaker.

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