4 breakers tripping all at the same time

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MannyBurgos

Senior Member
Location
Waukegan, IL
Hey all,

I have a situation that i've never experienced before. Got called to a job where main breaker was constantly tripping. While i was there, random circuit breakers would trip including main breaker at times. sometimes only one breaker would trip and other times 3 or 4 breakers would trip at the same time. Checked for continuity between all wires across each other and checked for continuity between wires an EGC and all checks out. This thing has me puzzled. Anyone experience this before? It is a 100 amp square d homeline panel. There are actually 2 main 100 amp breakers. I at the panel and 1 at the meter socket. The one at meter socket is the main that keeps tripping along with the branch circuit breakers. Checked the feeders and they are in good condition. Im puzzled....
 
Put a peak catching ammeter in place. You are almost certainly getting an arc or intermittent short circuit in a load somewhere.
The multiple branch breakers tripping is the only part that does not fit though.
 
Check for hot breakers and/or aged breakers that might trip on lower than nominal current or on vibration.
Hmm. If the branches have large motors running, a short upstream might pull enough backfeed to trip a branch breaker.
A Megger test might show a wiring problem.
 
GoldDigger said:
Check for hot breakers and/or aged breakers that might trip on lower than nominal current or on vibration.
Hmm. If the branches have large motors running, a short upstream might pull enough backfeed to trip a branch breaker.
A Megger test might show a wiring problem.
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This is actually an apartment with no motors. Actually, we disconnected everything and made sure that everything was completely off. It still trips after a few minites and at times instantly. I think i agree and will have to meg it out. Now i will need to go amd find a megger....
 
MannyBurgos said:
This is actually an apartment with no motors. Actually, we disconnected everything and made sure that everything was completely off. It still trips after a few minites and at times instantly. I think i agree and will have to meg it out. Now i will need to go amd find a megger....
Click to expand...
Are the breakers that trip all on the same buss if so swap on opposite buss and see if it is one leg causing issue meg that leg check connection see if it is loose 'heating up buss etc
 
MannyBurgos said:
It is a 100 amp square d homeline panel. There are actually 2 main 100 amp breakers. I at the panel and 1 at the meter socket. The one at meter socket is the main that keeps tripping along with the branch circuit breakers. Checked the feeders and they are in good condition. Im puzzled....
Click to expand...
I see you found your cause, but wanted to mention the breaker at the meter is socket is very likely a different type then the main in the panel - with a different trip curve and is probably a curve that would trip before the one in the panel.

A factory installed main in a Homeline panel is likely the QOM1VH series with a 22k interrupt rating. Good chance that your breaker at the meter is a 10k interrupt rating. Though that doesn't tell us the trip curve - they likely are different.
 
John120/240 said:
Glad that you found the problem. Now the question is "What caused the insulation to burn off". You don't want this to happen again.
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It actually looks like 1 guy originally pulled the wires 40 feet away. Had nicks throughout the wires. Wires were enclosed in 3/4" emt under concrete and we had a smooth pull with our new wires so we determined that connections were still intact. I megged out wires after installation and all were good. I assume it was original installer error....
 
kwired said:
I see you found your cause, but wanted to mention the breaker at the meter is socket is very likely a different type then the main in the panel - with a different trip curve and is probably a curve that would trip before the one in the panel.

A factory installed main in a Homeline panel is likely the QOM1VH series with a 22k interrupt rating. Good chance that your breaker at the meter is a 10k interrupt rating. Though that doesn't tell us the trip curve - they likely are different.
Click to expand...

Oh i forgot to mention that one. Feeders from main disconnect to subpanel are actually aluminum conductors with asphalt cloth covering. Actually found arcing marks inside the nipple between main disconnect and sub. You can actually see arcing whenever 2 or more breakers tripped due to overcurrent. This service has 8 meters with a common trouf where the feeders run to each panel and you can actually see what appears to be some liquid-grease substance on the inside of the trouf. Probably due to overheating and wear of the aluminum asphalt-cloth conductors....

We did replace the feeders and subpanel for the unit we were working on.
 
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