AFCI and generators

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scottdbutcher

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I went to a customers house yesterday to add on a 10 circuit generator panel, no ATS or anything fancy, basic line/off/gen switch. Anyhow he wanted his master bed on one cir, and it was a seimens AFCI. I have never done TS with AFCI's and warned him that it may not work.

It worked on line power fine, as soon as it was kicked to gen, the afci tripped. Of course. I would love to know how the MFG approaches this issue, other than the obvious "cant do that circuit" which as we all know is not really an option with some ppl. Anyone have any experiance with this?
 
scottdbutcher said:
I went to a customers house yesterday to add on a 10 circuit generator panel, no ATS or anything fancy, basic line/off/gen switch. Anyhow he wanted his master bed on one cir, and it was a seimens AFCI. I have never done TS with AFCI's and warned him that it may not work.

It worked on line power fine, as soon as it was kicked to gen, the afci tripped. Of course. I would love to know how the MFG approaches this issue, other than the obvious "cant do that circuit" which as we all know is not really an option with some ppl. Anyone have any experiance with this?
Click to expand...

I have heard similar issues with the AFCI and the generators. Many work fine while others have problems. Did you change out the AFCI?
 
Dennis Alwon said:
I have heard similar issues with the AFCI and the generators. Many work fine while others have problems. Did you change out the AFCI?
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The voltage regulation of the generator and the cycling inrush load on the generator could all produce current profiles that would 'confuse' the AFCI. It's a crapshoot until the algorithm becomes more sophisticated in couple of generation down the street.

I would suspect the larger and better generators would have a more accurate voltage regulators and if the individual loads are 1/5 th or even smaller of the generator size and not switched frequently, you would have a better chance of keeping the AFCI's 'alive'.
 
I didnt have a seimens afci on the truck, so i didnt change it. Not sure if that will make a difference. I explained the purpose and NEC reasoning of the AFCI to the customer, and he would rather have a regular 1p breaker, but i was going to try changing the AFCI before i result to that.......... I agree with weressl, but that unfortunatly dosent slove the problem! I live in an area where power loss if frequent and these systems are all over the place. I cant just go to a customers house and say oh, sorry cant put that in for you, you have AFCI's it wont work! Anybody else run into this or solve the problem? I know my solution....................... not really the right one though.....:D
 
scottdbutcher said:
I didnt have a seimens afci on the truck, so i didnt change it. Not sure if that will make a difference. I explained the purpose and NEC reasoning of the AFCI to the customer, and he would rather have a regular 1p breaker, but i was going to try changing the AFCI before i result to that.......... I agree with weressl, but that unfortunatly dosent slove the problem! I live in an area where power loss if frequent and these systems are all over the place. I cant just go to a customers house and say oh, sorry cant put that in for you, you have AFCI's it wont work! Anybody else run into this or solve the problem? I know my solution....................... not really the right one though.....:D
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You can explain it to them that when they operate under generator service the AFCI operation may become unpredictable and that tripping does not necessarily means that there is a problem. Instruct them of the use, test and reset procedures, based on the manufacturer's instructions, and be on your way.:)
 
Laszlo,

If a delay relay was installed on the afci circuit, would that cure the inrush
and allow the afci circuit to function properly?
 
benaround said:
Laszlo,

If a delay relay was installed on the afci circuit, would that cure the inrush
and allow the afci circuit to function properly?
Click to expand...

I am not sure the circuitry of what you imagine, but my hunch is that it would not 'cure' the problem. If you explain your idea a little more in detail maybe I can get a better 'hunch', but maybe you too.....:D
 
The circuitry doesn't matter, the gen. starts and 60 sec. later the afci circuit
comes back on line. Your comment was the gen's inrush current was most
likely the culprit to tripping the afci c.b. , so if you can delay that part maybe
the c.b. won't trip, or get changed to a regular c.b.
 
When inspecting homes with no power I use my generator. This tripping has never happened that I know of and the Ideal AFCI receptacle tester will not trip the device by itself. The circuit has to be tripped at the breaker itself. Of course this may be due to the size of the generator itself as I am using 125 volts at 2500 watts. Again this is only for inspection purposes.
 
ill have to change the acfi out, it is a few years old, maybe a fresh one wouldnt trip like this one does, i also waited for the inrush current to subside before resetting with the same effect (trip). New breaker it is!
 
scottdbutcher said:
ill have to change the acfi out, it is a few years old, maybe a fresh one wouldnt trip like this one does, i also waited for the inrush current to subside before resetting with the same effect (trip). New breaker it is!
Click to expand...

The old siemens had problems anyway. I would change it. Let us know the results
 
benaround said:
The circuitry doesn't matter, the gen. starts and 60 sec. later the afci circuit
comes back on line. Your comment was the gen's inrush current was most
likely the culprit to tripping the afci c.b. , so if you can delay that part maybe
the c.b. won't trip, or get changed to a regular c.b.
Click to expand...

Yeah, that would work for THAT scenario. I suspect that as equipment - such as freezers, AC and well pumps - start/stop while the genny is running would not be remedied by this solution.
 
I haven?t really had a chance to think this scenario through thoroughly, as it takes time for things to percolate the sieve that is my brain, but was wondering if the generator neutral was connected to ground either at the generator frame or inside the cabinet of the 10-ckt transfer panel, could this possibly cause this type of AFCI tripping issue?
If so, could a manual transfer switch that isolated the neutrals and created a true separately derived system help?
 
KJay said:
If so, could a manual transfer switch that isolated the neutrals and created a true separately derived system help?
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That was exactly what was proposed by a fellow I know. He thinks that if the transfer switch insluded the grounded conductor then the issue would not be there. If that were the case it would seem to be there all of the time. He thinks the utility neutral may cause the issue. Not sure how but....
 
I didnt open this perticular switch to see if the neautral and ground were isolated, but they should be from the mfg for the sole purpose of using this on a subpanel where grounds and neautrals need to be seperated. I cant imagine ul listing board would let that slide, b/c they would always be connected in the switch defeating (hypotheticly) the purpose of islotaing neautrals and grounds in a sub. There is nothing said about hooking up / not hooking to a subpanel in the instructions, and it also never mentions anyhting about gfi/afci potectred circuits either........
 
I was just mulling over my own 10-ckt Gen-Tran panel connections in my head.
If you are using the Gen-Tran type switches, don?t you take power from the load side of the AFCI cb?
This could most likely the problem.
When you transfer to the generator you are breaking the load side of the AFCI and it probably senses this imbalance and trips.
If this turns out to be the problem, unless you actually install the AFCI cb in an generator breaker type priority panel board, I can?t see how it will work.
 
Dennis Alwon said:
The old siemens had problems anyway. I would change it. Let us know the results
Click to expand...
I heard from a CH rep that when Arc Fault first came out, the were making them for everybody, Siemens, Square D, ect, due to their manufacturing facilities were not building them yet. We also have Cutler Hammer to thank for Arc Fault protection.
 
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