AFCI's tripping on generator start-up

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goldstar

goldstar

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Location
New Jersey
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Electrical Contractor
A friend called me the other day and asked what would cause AFCI's to trip on generator start-up. This is happening during the exercise cycle. The HO is concerned that if he is away and has a power outage that he'll come home to frozen pipes and/or flooding. I don't recall if the unit was a Generac or a Kohler but the breaker panel is Square D. Have any of you experienced this ?
 
I have heard of this years ago but I thought the issue was resolved. I would change the afci's to the newest generation and see if that helps
 
goldstar said:
A friend called me the other day and asked what would cause AFCI's to trip on generator start-up. This is happening during the exercise cycle. The HO is concerned that if he is away and has a power outage that he'll come home to frozen pipes and/or flooding. I don't recall if the unit was a Generac or a Kohler but the breaker panel is Square D. Have any of you experienced this ?
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You said this during exercise cycle, most of them don't transfer any load during exercise cycle do they? If not then it must be some sort of interference issue rather than a current issue.
 
goldstar said:
The HO is concerned that if he is away and has a power outage that he'll come home to frozen pipes and/or flooding.
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Is the furnace on an AFCI? If not at least you could assure the homeowner that the tripping problem won't cause such damage, even though it obviously needs to be fixed.

There is a connection from the generator unit to the utility power for monitoring whether power is present, charging the battery, etc. independent of the transfer switch. So that might be where interference is being conducted that's tripping the AFCIs.
 
Dennis Alwon said:
I have heard of this years ago but I thought the issue was resolved. I would change the afci's to the newest generation and see if that helps
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And if one breaker can be picked that consistently or at least frequently trips, then as a test case that breaker could be replaced with a new one to see if that helps before replacing all of them.
 
romex jockey said:
If there's an N/G bond anywhere in the genny system, a toroidal might pick up on it ~RJ~
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^Especially if the large (and noisy) current through the starter motor is passing through a ground path between the unwanted N/G bond point and the equipment ground connection point in the generator. That could create noise on the neutral that might trigger the AFCI breaker.
--Just speculating on possible causes.
 
kwired said:
You said this during exercise cycle, most of them don't transfer any load during exercise cycle do they?
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I'm reaching out to my friend to verify that. It doesn't make sense that they would trip on the exercise cycle.
 
synchro said:
^Especially if the large (and noisy) current through the starter motor is passing through a ground path between the unwanted N/G bond point and the equipment ground connection point in the generator. That could create noise on the neutral that might trigger the AFCI breaker.
--Just speculating on possible causes.
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which would be the 12V system most genny's have.

indeed grand speculation synchro

~RJ~
 
OK. I have a correction to the OP. The AFCI's trip on transfer to gen power during an outage. The breakers were able to be reset during the outage and remained on until the transfer back to POCO power. Breakers did not trip upon return to POCO power. Sorry for the mix up.:slaphead:
 
goldstar said:
OK. I have a correction to the OP. The AFCI's trip on transfer to gen power during an outage. The breakers were able to be reset during the outage and remained on until the transfer back to POCO power. Breakers did not trip upon return to POCO power. Sorry for the mix up.:slaphead:
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Post #2 stands as is.

QOs history would support the suggestion of the latest AFCI replacements.
 
Just as a point of clarification, this is a fairly new installation (both breaker panel and generator). It was completed within the past year. If I find out more info I'll post it.
 
It’s worth contacting your breaker manufacture rep or have supply house contact them because they may replace them with the latest version at no cost. At least this is what Siemens does for me when I have major issues with erroneous tripping related with equipment.
 
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