Main Breaker Problem

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sean1

Member
In May of 2006, I installed a 50 amp circuit for a spa in a 100 amp Bryant meter distribution panel with pop-in breakers. I noticed at that time that the main breaker body had melted around the areas that clip onto the buss on both phases. I replaced the main breaker. On 8/25/06 I got a call to the same residence that there was no power to the house. When I arrived on site, I noticed the same problem with the main breaker. I changed the main breaker again, and went back on 8/26 to inspect, and already noticed that heat damage was starting to occur. Besides the usual convenience lighting and regular household circuits, the only large amperage draws are for a 30 amp oven circuit and a 40 amp AC circuit. Customer keeps AC circuit off and cools his house with 2 120 volt evaporative coolers powered by existing plug circuits. No individual circuits trip and all other breakers appear to be in good condition. My theory is that there is too much load on the buss system, collectively from all circuits, and it is causing the buss to overheat. I reccommended that the customer upgrade his service to 200 amps. Am I on the right track, or am I missing something?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
When there is heat damage at the breaker/bus connection, you need to replace both the breaker and the bus. You found out what happens when you only replace the breaker.
Don
 

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
If those main breakers are not specifically listed (matched) for the panel, arcing from inproper tollerances would not surprize me. Same thing if that panel buss was previously scratched or damaged by forcing unlisted breakers.

It would surprize me if a frequency meter or RMS-clamp meter found high-Hz currents, under 100 amps, generating skin-effect heating on that bus. It seems to me, all the breakers and equipment loads would suffer the same heat problems, if it was frequency related.
 

marcb

Banned
Location
Roseville
I have to say the buss was damged when the first breaker had burned and most likely caused the failure the second time. The buss should have been replaced with the breaker. I doubt the "collective load" caused the main to fail. I see alot of main breaker replacements and for some reason nobody seems to address the buss and 99% of the time there is alot of damage. If all the parts are not in great condition then they will fail.
 

charlie tuna

Senior Member
Location
Florida
one,
your first clue was when you found the damaged main breaker --- and you realized it was a 100 amp breaker ---- and the customer was asking you to add a 50 amp load to this problem.......... when a breaker gets hot enough to discolor it's bus stabs and/or the bus is discolored -- replacing the breaker is only a temporary fix. the original load is too high. yes your customer is going to tell you he never runs the a/c of never uses the oven -- but something caused the original damage to that main breaker. the addition of the spa should have been reason alone to tell your customer he needs a service change. can you imagine the damage this is causing to all his computerized appliances?? once the customer understands the effects of running 150 load on a 100 amp bus --- he will gladly dig down and spring for the 200 amp service change. it is the job of the electrician to educate the customer and if he doesn't listen --- reach out and shake his hand as you leave......
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
something screwy here. I agree with don. there is clearly something causing excess heat and from your description it is not excess current. excess current would just trip the main.
 

marcb

Banned
Location
Roseville
petersonra said:
something screwy here. I agree with don. there is clearly something causing excess heat and from your description it is not excess current. excess current would just trip the main.
You should do a load calculation before you just change the panel. You should address the problem instead of changing the part until you find the fix
 

dave1976

Member
you might want to cheak the a/c i had a 3 p 208 600 amp main breaker heating up and tripping. the problem was a compressor in an a/c unit. the melted the main breaker but in the a/c panel all the breakers were cool to the touch.
 

sean1

Member
Main Breaker Problem

Thanks guys, for your reponses, and sorry it took so long for me to get back to you. According to my suppliers, Bryant is no longer in business and original buss and breakers are not available, and therefore cannot be replaced. At the initial hook-up of the spa, I told the customer that a service upgrade was going to be required, but he wanted to see if his system would work by disconnecting the 30 amp dryer circuit and using the space for his spa. I've gotten the ok to do a 200 amp service upgrade, and I think that this will take care of his problems.
 

celtic

Senior Member
Location
NJ
sean1 said:
According to my suppliers, Bryant is no longer in business and original buss and breakers are not available, and therefore cannot be replaced.
I think your suppliers have a strong desire for filet of sole....
boot-sole.jpg

...this kind of sole, usually attached to a boot or shoe and a foot.

Your suppliers are telling you that now the millions of Bryant panels that have been installed over the years are all obsolete? Heck...you can buy replacements for FPE and that's a worse choice than Bryant.

Here's a thread from a few months ago where replacements for Bryant CB's was discussed:
[Cutler Hammer / Bryant Breakers]

Your suppliers might want to reconsider their diet :)


Good deal on selling the service upgrade...just keep in mind there ARE replacements for Bryant CBs.
 
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