Puzzling GFI trip on coffee maker.

F

fastline

Senior Member
Location
midwest usa
Occupation
Engineer
This is my own, nothing urgent, but I am sort of wanting to know. The other day I realized I had circuits off. Check breaker, had a GFI trip. That's usually not good. Unplugged a bunch of stuff, got it back online knowing that wasn't the end of it. Next day was the same, but realized it was when I was making coffee.

I've narrowed this down that the coffee maker runs on the circuit just fine until it gets all the coffee made and the thermal switch kicks out, when it kicks back in to reheat, that's it, and it will then blow the the GFI instantly. Let it cool, it works.

This is not an AFI breaker, but it might be doing AFI things? I sort of suspect a flaky thermal or relay. There is no ground pin so no way to check that. Is this an excuse to buy a new gadget that can capture the amount of imbalance at trip?
 
If you put in a different coffee maker does it still trip? How long has this coffee maker been on this circuit before it started tripping like that?

It sounds like a issue with the coffee maker.

I would try the coffee maker on another circuit first. Just to see if it is unique issue to that circuit. Like maybe on the receptacle near the AC unit. I would then probably buy a receptacle type power monitor and see if it captures it.
 
Spoke too soon. Realized I didn't follow diag 101 and move to another receptacle. I ran a test and the coffee cooker ran perfect, no trips, same circuit, different recep. I will have to open that box later and see what's up in there.
 
fastline said:
Spoke too soon. Realized I didn't follow diag 101 and move to another receptacle. I ran a test and the coffee cooker ran perfect, no trips, same circuit, different recep. I will have to open that box later and see what's up in there.
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Was that other receptacle that you tested with fed off the load side of the GFCI receptacle that was tripping?
 
Sounds like the trip is due to electrical noise. Moving to a different receptacle likely changed the impedance between the coffee maker and the breaker, (longer conductors?) and attenuated the noise enough to alleviate the problem.
 
retirede said:
Sounds like the trip is due to electrical noise. Moving to a different receptacle likely changed the impedance between the coffee maker and the breaker, (longer conductors?) and attenuated the noise enough to alleviate the problem.
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Technically the recep that worked is further away from the source. The load has been on that other recep for years without issue. Super odd that it would trip only after getting hot. That one is throwing me for a loop.
 
fastline said:
Technically the recep that worked is further away from the source. The load has been on that other recep for years without issue. Super odd that it would trip only after getting hot. That one is throwing me for a loop.
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Perhaps the contacts on the thermal switch are getting pitted/eroded and the arc when it breaks is bigger and generates more noise now than it did previously?
 
Breaker is GFI. Different recep on same circuit apparently worked so far, so that sort of points to the recep. This CM is ultra cheap, only one element as many in that class have. For the time being, I will just leave the CM on the new recep and see if it trips before I go tearing into the recep. I was actually at Wally last night trying to buy another CM, convinced it was hosed.

I've worked on many CMs but this one ain't worth touching at $12. Torn down a Bunn when at an electric co, with all the electricians standing around me because we had no coffee!!! You wanna talk about an emergency!
 
fastline said:
Breaker is GFI. Different recep on same circuit apparently worked so far, so that sort of points to the recep. This CM is ultra cheap, only one element as many in that class have. For the time being, I will just leave the CM on the new recep and see if it trips before I go tearing into the recep. I was actually at Wally last night trying to buy another CM, convinced it was hosed.

I've worked on many CMs but this one ain't worth touching at $12. Torn down a Bunn when at an electric co, with all the electricians standing around me because we had no coffee!!! You wanna talk about an emergency!
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Folgers or Maxwell House??🤔
 
I have a $15 one. It has two elements. Must be a step up from yours. The pot warmer and boiler are always on. The brewing just stops when the water boils away. Instant steam if you add water. Every week or so I brew a pot of vinegar to keep it going. I think three years for this one.
 
I have the same problem with my Kuerig coffee maker. It doesn't happen every time, maybe once every ten times and it happens right after brewing the cup of coffee. It is on a GFI outlet protected circuit. I figure it is time for a new coffee maker.
 
JZE14 said:
I have the same problem with my Kuerig coffee maker. It doesn't happen every time, maybe once every ten times and it happens right after brewing the cup of coffee. It is on a GFI outlet protected circuit. I figure it is time for a new coffee maker.
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Calling what comes out of a Keurig “coffee” is a stretch!
 
Well day two was a win on a different receptacle. Runs perfect. On the old recep, 2 days in a row was not only a tripped GFI, but I tested the hot CM several times and it would consistently trip the GFI immediately.

I will probably a find a loose screw when I get around to checking it....lol
 
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