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Norm
Norm, Master Electrician
Category: Electrical
Satisfied Customers: 67
Experience:  Registered professional electrical engineer and licensed master electrician.
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Have problems with electrical power into my home and property..

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Have problems with electrical power into my home and property.. have 400 AMP service coming in to electrical panel from PG&E but it appears that of the 2 200 AMP electrical feeds from PG&E is when under load dropping down to 0 volts or sometimes 53 volts AC.
My question is voltage going into top of 200 AMP breaker is 125v Ac but, is only reading 0-53 volts coming out bottom of breaker at same time.. It this breaker BAD as it looks to be or is there something else i should be checking..?

Norm :

Hi, I'm Norm and I'd like to help. Your readings indicate a failing connection on the affected breaker. It could be on the line or load side, but is most likely not the breaker itself. Depending on how badly the heat from the bad connection has damaged the terminals, the breaker might well have to be replaced. The safest thing to do is open that breaker and have an electrician test the breaker and connections to make repairs. ...... Norm

Customer:

Thank you Norm, I would open that breaker as you suggest but it is also part of a Double Breaker for all incoming power, and has Double single pull lever so to open one breaker i have to open both and cut off all all power to entire place and was trying to figure out before doing so, and scheduliing PG&E to cut power off so that breaker can be removed and replaced.. Just wanted to try to make sure if that was for sure the problem.. As you can understand, plus replacing price of replacing Double 200 amp breaker is not going to be cheap.. lol

Customer:

Oh also Norm, thought should meantion,, There does not appear to be any damage externally to breaker or any of the terminal connections of any kind, no discoloration or anything from heat..

Norm :

You are right on that. Since your readings were 120 Volts rather than 240, I assume you read between each pole and the neutral. You didn't mention any other problems, such as bright or dim lights, which would implicate the neutral. Your readings, it sounds like, were made between one pole of the breaker and neutral, then the load side of that same pole to neutral. That being the case, the problem is definitely a failing connection on the line or load side of that pole. Since you can't open just one breaker, I'd suggest opening the subpanel breakers on that feed to eliminate load on the failing connection. A failing connection can generate enough heat to cause a carbon-limited fault in the panel and subsequent fire. If you can't see the damage, the failure may well be inside the breaker, so I would strongle receommend eleiminating load on that breaker.

Customer:

Norm you are right on the money,,, I was checking reading on each pole and neutral because i discovered that only the one pole seemed to be having a problem,, and then proceeded to try to isolate down to if a problem with individual load breaker, taking all load off that pole and slowing adding back on, one subpanel breaker at a time, and found that no specific breaker along would cause the pole to drop but as i added more once it reach certain point a single 20 Amp breaker would cause if to instantly drop from 125v to 0 or sometimes 53-78volts.. then when opened 20 Amp breaker it would come back up to 125v.. But whole time it was low when i would check at top incomeing side of the pole's breaker the input voltage is still reading 125v. Does that all make sense. ?

Norm :

It makes perfect sense. That is the pole with the failing connection. The fact that the voltage drops under load is positive confirmation of a failing connection on that breaker.

Customer:

Great Norm, I really appreciate all your expert advise, I just wanted to make sure my logic was correct before preparing to power down entire place for replacement of that Very Large and intiminationg 400 amp breaker,,, because i have 2 other residences with tenants that are connected to this service that will be effected when i have to shut it all down. But I have no problem replacing regular breakers 100 amp or so,, with power live but can snap loose from backplane to work on or open breaker so safer. But this 400 AMP has no backplane just one big breaker with terminal on top and bottom and 200-400AMP is no joke,, it would do alot more that maybe hurt to get hit by it for sure... lol

Customer:

Thank you so much for all your help really appreciate it.. I will go ahead now and fill out the rating questions and release the deposit so you can get paid.. Thanks again Norm.

Norm :

Thank you. And good luck with your problem.

Customer:

You welcome thans..

Customer:

opps. You are welcome Norm...

Customer:

have a great day..

Norm and other Electrical Specialists are ready to help you
Hi Tim,

How did things work out? Is there anything else I can help you with?

Norm