2 pole 20 amp afci on multi wire branch circuit

crtemp

Senior Member
Location
Wa state
I had another electrician tell me this will not work on a multi circuit and it is only meant for a 240 volt circuit like wall heaters. Last I knew 240 volt circuits were not required to be afci. I've been using these for years on the SABC and the microwave circuit and have never had an issue. Now all of the sudden I have one that randomly trips. I've swapped out the breaker but it didn't seem to help. I've opened everything up and have no grounds touching neutrals anywhere. The gfi on the SABC holds fine as well. The home owner can't re create the problem when I'm there. Anything else I can try? Would a megger test tell me anything?
 

ramsy

Owner/Operator
Location
LA basin, CA
Occupation
Service Electrician 2017 NEC
No, nothing against code.
You missed a few things:
1) 110.3(B), If OEM says otherwise.

2) OP provides Link above, with "Question & Answer" section, just below "Specifications"
Question: "Does this fit a panel with br type breakers?"
Answered by: SIEMENS Product Expert:
"This circuit breaker is only UL listed to be used in a Murray panel..."

3) Look closer at product picture - See sticker on side, "Use only in Listed Enclosures"

Not listed for Cutler Hammer, or Eaton load centers.
 

crtemp

Senior Member
Location
Wa state
+1. Is fine for MWBC's otherwise, and until AFCI is required for 240 volt circuits MWBC's is all they are really intended for.
I'm still having problems with these. They are installed in a Eaton BR panel. It fits on the bus perfectly. Could this possibly have anything to do with them tripping? They hold fine when reset but once the microwave runs for about 10 seconds it trips. Or it will work fine for a few days and then start acting up again. I've had about 10 different breakers in 10 different houses with the same issue. Could it just be a bad batch of breakers from the factory?
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
I'm still having problems with these. They are installed in a Eaton BR panel. It fits on the bus perfectly. Could this possibly have anything to do with them tripping? They hold fine when reset but once the microwave runs for about 10 seconds it trips. Or it will work fine for a few days and then start acting up again. I've had about 10 different breakers in 10 different houses with the same issue. Could it just be a bad batch of breakers from the factory?
Welcome to the wonderful world of AFCI breakers!:thumbsdown:
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
I'm still having problems with these. They are installed in a Eaton BR panel. It fits on the bus perfectly. Could this possibly have anything to do with them tripping? They hold fine when reset but once the microwave runs for about 10 seconds it trips. Or it will work fine for a few days and then start acting up again. I've had about 10 different breakers in 10 different houses with the same issue. Could it just be a bad batch of breakers from the factory?
Swap it out temporarily with a gfci breaker to see if it is a problem with the circuit. If it holds then you've got a ghost chase on your hands.
 

crtemp

Senior Member
Location
Wa state
Swap it out temporarily with a gfci breaker to see if it is a problem with the circuit. If it holds then you've got a ghost chase on your hands.
I've swapped it with 2 other afci breakers and same problem. I haven't tried a gfci breaker but I have done a continuity test between the neutral wire and the ground bar in the panel without the neutral pig tail hooked up and I get nothing. Won't that produce the same result? Also again, this is happening with multiple breakers in multiple houses.
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
I've swapped it with 2 other afci breakers and same problem. I haven't tried a gfci breaker but I have done a continuity test between the neutral wire and the ground bar in the panel without the neutral pig tail hooked up and I get nothing. Won't that produce the same result? Also again, this is happening with multiple breakers in multiple houses.
I have no problem believing it's the AFCI swapping with a GFCI is just the easiest way to rule out other problems.
 

crtemp

Senior Member
Location
Wa state
I have no problem believing it's the AFCI swapping with a GFCI is just the easiest way to rule out other problems.
I've pretty much ruled it out to bad breakers. I just wanted to see if anyone thinks it could possibly be just because of a different brand breaker than what the load center is. I can't possibly think why it would matter but I figured I ask before I send the breakers back to seimens.
 

kwired

Electron manager
Location
NE Nebraska
Possibly microwave doesn't play well with AFCI's. Have you tried other substitute load - something with similar amp draw though like a heat gun or hair dryer?
 

crtemp

Senior Member
Location
Wa state
Possibly microwave doesn't play well with AFCI's. Have you tried other substitute load - something with similar amp draw though like a heat gun or hair dryer?
I was thinking of plugging in my conduit heater box and trying that but never got around to trying it. I'll give it a try tomorrow.
 

kwired

Electron manager
Location
NE Nebraska
I was thinking of plugging in my conduit heater box and trying that but never got around to trying it. I'll give it a try tomorrow.
If that trips it, the problem is likely in the branch circuit somewhere, otherwise the microwave just doesn't play well with AFCI would be my conclusion.
 

crtemp

Senior Member
Location
Wa state
If that trips it, the problem is likely in the branch circuit somewhere, otherwise the microwave just doesn't play well with AFCI would be my conclusion.
What would I even do at that point? Who's responsibility would it be to fix it? It's just very strange that I have been using these breakers for the last couple of years with no problems and now all of the sudden I have a bunch that trip (all on microwave circuits).
 

kwired

Electron manager
Location
NE Nebraska
What would I even do at that point? Who's responsibility would it be to fix it? It's just very strange that I have been using these breakers for the last couple of years with no problems and now all of the sudden I have a bunch that trip (all on microwave circuits).
I don't know what to tell you. If you want to follow code you are in a bad situation. I don't care if I do residential work anymore because of AFCI and stories like this. I have been lucky to not have any issues with AFCI's so far other then wiring problems that would have caused problems with GFCI's as well.
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
What would I even do at that point? Who's responsibility would it be to fix it? It's just very strange that I have been using these breakers for the last couple of years with no problems and now all of the sudden I have a bunch that trip (all on microwave circuits).
And now you know why there are one thousand AFCI haters for every AFCI defender.
 

crtemp

Senior Member
Location
Wa state
I don't know what to tell you. If you want to follow code you are in a bad situation. I don't care if I do residential work anymore because of AFCI and stories like this. I have been lucky to not have any issues with AFCI's so far other then wiring problems that would have caused problems with GFCI's as well.
Yes it's a f***ing nightmare. Makes me want to quit.
 

crtemp

Senior Member
Location
Wa state
The logic makes no sense either. What is the difference between a light in a bathroom and a light in a bedroom or a 20 amp counter top kitchen receptacle and a 20 amp bathroom receptacle. Why would one need to be on arc fault and the other doesn't. Or who cares how long the circuit is? Why if it's under 50 or 75 feet does it not need to be a breaker but it can be on an afci receptacle? Who comes up with this crap?:happysad::?
 

kwired

Electron manager
Location
NE Nebraska
The logic makes no sense either. What is the difference between a light in a bathroom and a light in a bedroom or a 20 amp counter top kitchen receptacle and a 20 amp bathroom receptacle. Why would one need to be on arc fault and the other doesn't. Or who cares how long the circuit is? Why if it's under 50 or 75 feet does it not need to be a breaker but it can be on an afci receptacle? Who comes up with this crap?:happysad::?
From recollection it started with consumer product safety commission wanting something to help prevent fires from arcing faults. The concept makes sense, they have not perfected anything that reliably does what was wanted, yet lobbied and maybe even outright lied about what they do have and what it can do to get it into code so they could start seeing returns on R & D. There are many threads here that hash this issue out, with only a small percentage of people who actually think the things are worthwhile. My opinion is if it would do what they said it would do it might be a good thing, but I don't think they do what their makers promise they will do. This then puts the electrical contractors right in the middle, code requiring them, customers not happy with them because of unexplained tripping issues, and manufacturers aren't the ones out in the field trying to figure out what is wrong.

Wiring issues are often a problem but there is still appliances with nothing wrong with them at times that don't want to play well.
 
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