AFCI issue

[beachbumjeremy]

Sorry if this is the wrong section, but couldn't find an appropriate spot. I Have a question regarding an AFCI issue. Two separate circuits both have an AFCI breaker. One for the smoke detector and smoke fire damper, the other for the bedroom receptacles and light. The bedroom light had not yet been installed, and the neutral was not capped off and it was sitting up against the metal box. When I turned on the bedroom circuit, the AFCI did not trip. When I turn on the second AFCI, the first one tripped. Capping the neutral solved this problem, but I can't figure out why turning on the second AFCI would cause the first to trip. I already verified the neutral are landed correctly and nothing is crossed....so any ideas why this happened?

 

[480sparky]

My first guess would be the neutrals are tied together somewhere.

Or the labels are switched.

You say you have verified the neutrals in the panel. What about the hots?

 

[beachbumjeremy]

Yes, I verified the hots as well. I also know the way the unit was roped, and there is no way the neutrals are tied together.

 

[mdshunk]

When the original information given just doesn't make sense, the information given was incorrect. What you believe to be true is not. Keep checking. Confirm everything that you've assumed is true is actually true.

 

[radiopet]

Marc- You should make that into a sticker...Like Charlies Rule...lol

I agree that is sounds like something is missing here, The only reason that I could think of that would make this happen is somewhere in the layout you have something crossed, mis-labeled or mis identified or mis re-identified and so on.

Check it all again even if it means opening up all connections.

 

[beachbumjeremy]

After this incident, my boss told me the same thing, something is crossed. I told him like I say here, nothing is crossed, so he came and looked himself. Nothing is crossed. C-10 goes straight to the smoke detector and then to the smoke fire damper. C-8 goes to the bedroom and loops through. It has been checked and double checked that nothing is crossed. I guess no one has experienced this before?

 

[76nemo]

After this incident, my boss told me the same thing, something is crossed. I told him like I say here, nothing is crossed, so he came and looked himself. Nothing is crossed. C-10 goes straight to the smoke detector and then to the smoke fire damper. C-8 goes to the bedroom and loops through. It has been checked and double checked that nothing is crossed. I guess no one has experienced this before?

Sorry Jeremy, have to agree with the rest, something somewhere is touching. Did you remove the conductors and megg them seperately?

 

[al hildenbrand]

After this incident, . . .

It has been checked and double checked that nothing is crossed. I guess no one has experienced this before?

I'm not clear. Was this a single shot event, or has it be repeating intermittantly or consistantly? Is it still happening?

Have you tried uncapping that light neutral and putting it back in contact with the ground?

Edit to add one more question.

 

[beachbumjeremy]

Yes, this was a one shot event. I did try uncapping it and seeing what happened. It's still the same. All the other units so far appear to be fine as I continue to trim.
With the fixture in, there is also no problem with either AFCI breaker. So I'm still clueless.

 

[76nemo]

Yes, this was a one shot event. I did try uncapping it and seeing what happened. It's still the same. All the other units so far appear to be fine as I continue to trim.
With the fixture in, there is also no problem with either AFCI breaker. So I'm still clueless.

One shot????? Does the problem remain, or not?

 

[al hildenbrand]

Yes, this was a one shot event.

Weird with a beard.

I'm clueless, too.:-?

 

[quogueelectric]

Was this a multi wire branch circuit?? Aka a 3 wire??

 

[al hildenbrand]

Was this a multi wire branch circuit?? Aka a 3 wire??

No.

He explains it in his posts. Two separate two-wire circuits.

 

[beachbumjeremy]

I meant 1 shot event as in this event is isolated to this one unit. But I was able to get the same results by uncapping the neutral.
Now the fixture is installed and there is no issue.