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Discussion Starter · #1 ·
Hello everyone. First time posting on here and I would love to get some advice on an issue that just popped up last night. First a little background:

I wired my basement myself a couple years ago, passed inspection. Wired a subpanel from the main box with a 60amp breaker. I believe I have 7 or 8 circuits on that subpanel all with AFCI breakers. I have had no trouble with the subpanel since I installed it, except a couple times with running the vacuum and one of those AFCI breakers would trip, which I know is a problem that does happen with that type of breaker.

Yesterday, however, I walked downstairs to my basement I noticed that now my lights wouldn't turn on, which I thought was strange. I walked over to panels and noticed that on the subpanel 4 or 5 of the breakers were tripped. I have never since that before where multiple were tripped. My first thought was that my wife was vacuuming yesterday down there and keep tripping the breakers and had to move the vacuum to different locations. So I decided to flip the breakers back on and on a couple of them, I could hear a sizzling sound coming from the panel located on each circuit breaker themselves like they weren't getting a good connection. But once I reset them, the sound stopped. So, I went back upstairs and went to bed.

This morning I asked my wife about the vacuuming and she said she only used one outlet down there yesterday, but today when she went down there she noticed that the bathroom light was not working. So, I went back down there to investigate and sure enough, the bathroom lights weren't working and that one breaker had tripped again. So, I reset it again, didn't hear any sounds coming from the sub panels, and it stayed reset so, I went into the bathroom and turned the light on to see if I could recreate the problem. As soon as I turned the vanity light one, I noticed it went dim and then I could hear multiple breakers popping in the panel. This, of course, made me very concerned. I went back to the sub-panel and noticed that around 3 to 4 breakers had tripped all at once and when I tried to reset a couple of them, I could hear that sizzling sound coming from the circuit breakers again even after it had reset, so I finally just went into the main breaker and turned off the whole subpanel. These seemed to stop the sounds coming from the sub-panel, which made sense to me. The only thing I can figure of why multiple breakers could trip at the same time, is if my feeder cable coming from the main to the sub-panel is loose in the sub-panel, but that is just a guess on my part, I didn't have time to open up the panel yet and investigate further. I just have never seen multiple breakers trip at the same time, and with no load on them for that matter.

Does anyone have any suggestions or have seen this problem before with a subpanel? I will be going back home in a couple hours and I will open up both panels to see if I notice any loose wire. Thanks, everyone for the help!
 

· Electrician
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I have actually encountered this before.

Turn the power off before starting.

Check to make sure all the connections are tight in the sub-panel.
There may be 1 breaker that is causing them all to trip.

In my case, it was the breaker feeding the sub-panel. It was loose on the bus, and the sub-panel was Siemens breakers.

Remove each breaker from the sub-panel and check to see if there are any signs of arcing. If you see any black marks or any discoloration, it's usually a sign that there has been arcing happening.
Another sign there may be arcing happening is if the breaker is too loose on the bus in the panel. When you remove or install a breaker there should be some force required. If it comes out too easily (or goes back in too easily) there may be an issue with the connection on that breaker.
A quick way to tell if one is too easy is to test them all. It's unlikely (but still possible) that all the breakers in the sub-panel would be too loose for the bus. They should all feel about the same to remove and re-install.

If there isn't anything in the sub-panel that is happening, check to make sure the breaker feeding the sub-panel is tight and not arcing.

Keep in mind that it doesn't have to be an arc-fault breaker that is causing the arc-fault breakers to trip. A normal breaker can cause them to trip. (Or at least in my case it was a normal breaker).
 

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Discussion Starter · #3 ·
Thanks for the help, Kevin. I do believe there was some arcing because I could hear it when I reset some of the breakers in the subpanel. When I get home in a couple hours I will open up both panels, turn off the main breaker:biggrin2:, and look for any loose connections. So in the main panel, if the feeder breaker is tight than one of the subpanel circuit breakers could be loose and causing several of them to trip? Wow, I didn't know that could happen.

I will post again, once I get into the panels and have a look around.
 

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Discussion Starter · #4 ·
One more thing Kevin. if I do find that some of the circuit breakers in the subpanel have been arcing and do have discoloration, can I still use those going forward? I would assume so, but want to be sure. Thanks again
 

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Discussion Starter · #5 ·
Thanks for the help, Kevin. I do believe there was some arcing because I could hear it when I reset some of the breakers in the subpanel. When I get home in a couple hours I will open up both panels, turn off the main breaker, and look for any loose connections. So in the main panel, if the feeder breaker is tight than one of the subpanel circuit breakers could be loose and causing several of them to trip? Wow, I didn't know that could happen.

One more thing Kevin. if I do find that some of the circuit breakers in the subpanel have been arcing and do have discoloration, can I still use those going forward? I would assume so, but want to be sure. Thanks again

I will post again, once I get into the panels and have a look around.
 
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