Uneven voltage on legs at main panel - troubleshooting?

[JoeMX82]

I have two main panels each 150amp breaker. House was built in 83 and lived here for 6 years no issues. About 6 months ago we had a power surge and our main ac fail (hard short) and tripped the breaker. Had the unit replaced but it seems since then we have had issues with lights diming and electronics where you can hear them surging. I decided to do some testing and when I put my volt meter on the incoming mains I get some decent flucations. With nothing on in the house the range is like 115 on one side to 125 +|- 3 or so volts. But when we turn on a microwave for example it goes to 105 and 135. Assuming that is not normal?? No obvious signs of damage in the panel and I had the power company come look at the meter but they came when I wasn’t home and told my wife everything was normal - who knows. Any advice on what to do next?

 

[Megawatt]

I have two main panels each 150amp breaker. House was built in 83 and lived here for 6 years no issues. About 6 months ago we had a power surge and our main ac fail (hard short) and tripped the breaker. Had the unit replaced but it seems since then we have had issues with lights diming and electronics where you can hear them surging. I decided to do some testing and when I put my volt meter on the incoming mains I get some decent flucations. With nothing on in the house the range is like 115 on one side to 125 +|- 3 or so volts. But when we turn on a microwave for example it goes to 105 and 135. Assuming that is not normal?? No obvious signs of damage in the panel and I had the power company come look at the meter but they came when I wasn’t home and told my wife everything was normal - who knows. Any advice on what to do next?

I’m not understanding what you mean by replacing the unit. It sounds like you have a neutral problem. If your voltage is fluctuating then you need to check your # 6 bare wire is attached to the ground rod from the panel and make sure that it is tight in the panel. Also you have to install a surge suppression device or SPD. Sorry I can’t be of much help, if you have anymore info or pictures would be very helpful.

 

[JoeMX82]

I’m not understanding what you mean by replacing the unit. It sounds like you have a neutral problem. If your voltage is fluctuating then you need to check your # 6 bare wire is attached to the ground rod from the panel and make sure that it is tight in the panel. Also you have to install a surge suppression device or SPD. Sorry I can’t be of much help, if you have anymore info or pictures would be very helpful.

I appreciate the reply and since my original post I have had some success. It was a broken neutral between transformer and meter - poco ran a temporary fix above ground to my meter and I’m waiting on them to fix them main underground cable. For now, with the temp fix, voltage is steady on both legs. I have checked my grounding and found only one of my two rods was being use so I ran a new #4 bare copper wire and connected both rods. I will also be installing surge protectors on my panels but one panel is full so might be getting a larger panel (more spaces) to help with that.

 

[Megawatt]

I appreciate the reply and since my original post I have had some success. It was a broken neutral between transformer and meter - poco ran a temporary fix above ground to my meter and I’m waiting on them to fix them main underground cable. For now, with the temp fix, voltage is steady on both legs. I have checked my grounding and found only one of my two rods was being use so I ran a new #4 bare copper wire and connected both rods. I will also be installing surge protectors on my panels but one panel is full so might be getting a larger panel (more spaces) to help with that.

Depending on what type of panel you have you can buy slim line breakers for your panel and free up space for your SPD. Good luck my friend