Home Electrical power faults (question)

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Feb 15, 2003
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Jupiter, Florida
I am not home, mama (wife) is troubleshooting over the phone. We are having trouble with one leg of power. When the 120V gas dryer kicks on, the UPS’s in the den go a-beeping and the internet drops out for a sec (despite being on a UPS) Voltage sags to 60, then recovers. Same with the microwave and the 120V air compressor won’t start Unless empty. I did change the start and run caps in the compressor motor, thinking that was a separate issue. But it seems not.

I believe all are on the Left set of breakers.

The main breaker is fairly new. The meter is electronic with an internal disconnect.

None of the breakers are warm.

I’ll be home on Saturday and will do some measurements. Thoughts on troubleshooting tips are appreciated. I’m a capable guy, understand electrical power and know how to be safe. But I don’t have all the answers and maybe there are troubleshooting tips that will help me determine if the problem is not at my home.

we have non stop brownouts when Windy. As the trees touch the local lines. Yet my power lines are buried From the pole to house.
 
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The problem could still be the buss bar connection, just alternate breakers. The OP wasn't real specific about which breakers on the left.
 
Since all of the affected breakers are on the same side of the panel then your issue is NOT confined to one leg . The bus bar connectors alternate back and forth . You need somebody to open that panel up and do some real troubleshooting .
Good point, thanks. I had forgotten about that aspect of breaker boxes. Still could be one leg though. I'll have to carefully note each.

The 240V 2HP well pump starts, no problem, and does not seem to cause a big voltage sag. So I am thinking it's not the pole transformer. However, I will have to study that one a bit more too.
 
The problem could still be the buss bar connection, just alternate breakers. The OP wasn't real specific about which breakers on the left.
I just don't recall at the moment. I will get my wife to text a pic. The good news is, the meter is easy to remove as it is on the generator transfer box outside, and the Main breaker is also outside.

I've had to change the main breaker before due to one leg being out. I did not disassemble the unit, but I suspect it was corroded. It is Florida after all, and the humidity is epic.
 
I just don't recall at the moment. I will get my wife to text a pic. The good news is, the meter is easy to remove as it is on the generator transfer box outside, and the Main breaker is also outside.

I've had to change the main breaker before due to one leg being out. I did not disassemble the unit, but I suspect it was corroded. It is Florida after all, and the humidity is epic.
You most likely know but to me maybe the transfer box is the first place to look? After all it disconnects power to the grid and reconnects it when power is restored. Since it doesnt seem like a common issue in homes and most homes dont have a transfer box might make sense to check?
 
It sounds like the neutral circuit is open. The neutral wire to the pole constrains the voltage on both "legs" to be 120 volts to neutral. If the neutral is no longer connected to the center tap of the pole transformer, the voltage will arbitrarily divide. When a heavy load is applied to one side, that side drops and the other one rises. The rise on the other side can burn out 120 volt appliances.

240 volt circuits are not affected because they don't use the neutral.

As others said she needs to turn off the main breaker until it is checked out and repaired.
 
Who is the maker for your home panel box? How old is your house is it the original load center. I ask that because there have been some recalls/field repairs on some load centers because of some loose neutrals in the load center/ panel box.
 
It sounds like the neutral circuit is open. The neutral wire to the pole constrains the voltage on both "legs" to be 120 volts to neutral. If the neutral is no longer connected to the center tap of the pole transformer, the voltage will arbitrarily divide. When a heavy load is applied to one side, that side drops and the other one rises. The rise on the other side can burn out 120 volt appliances.

If your power company is decent, they'll check for an open neutral between the meter and transformer before telling you to call an electrician. It's kind of like they realize that they should make sure that the problem isn't on their side of the meter first.
 
It sounds like the neutral circuit is open. The neutral wire to the pole constrains the voltage on both "legs" to be 120 volts to neutral. If the neutral is no longer connected to the center tap of the pole transformer, the voltage will arbitrarily divide. When a heavy load is applied to one side, that side drops and the other one rises. The rise on the other side can burn out 120 volt appliances.

240 volt circuits are not affected because they don't use the neutral.

As others said she needs to turn off the main breaker until it is checked out and repaired.
Thank you! That’s a great place to start!
 
Who is the maker for your home panel box? How old is your house is it the original load center. I ask that because there have been some recalls/field repairs on some load centers because of some loose neutrals in the load center/ panel box.
The house was new in 2002. I will have to look at the panel box manufacturer when I return home.

it has been a while since I’ve looked inside. I remember the connections being very well torqued when it was installed.
 
Breakers on one side? might be a neutral buss on each side, I wonder if the tie between the two busses is loose. For that, you might be able to tie DMM to ground (service in), then to neutral on bad side. Kick on a heavy load. Should be little voltage rise on neutral inside the box.

Hard to capture transients unless if your meter has hold feature, but I suspect heavy loads will show a voltage drop somewhere.
 
One of the best indicators for a loose neutral is having some lights get BRIGHTER. This used to be obvious with incandescents, not sure how this'll go with modern energy saving LEDs.
 
I am not home, mama (wife) is troubleshooting over the phone. We are having trouble with one leg of power. When the 120V gas dryer kicks on, the UPS’s in the den go a-beeping and the internet drops out for a sec (despite being on a UPS) Voltage sags to 60, then recovers. Same with the microwave and the 120V air compressor won’t start Unless empty. I did change the start and run caps in the compressor motor, thinking that was a separate issue. But it seems not.

I believe all are on the Left set of breakers.

The main breaker is fairly new. The meter is electronic with an internal disconnect.

None of the breakers are warm.

I’ll be home on Saturday and will do some measurements. Thoughts on troubleshooting tips are appreciated. I’m a capable guy, understand electrical power and know how to be safe. But I don’t have all the answers and maybe there are troubleshooting tips that will help me determine if the problem is not at my home.

we have non stop brownouts when Windy. As the trees touch the local lines. Yet my power lines are buried From the pole to house.
FWIW and in keeping with the comments above, FPL now requires at least TWO ground rods at the meter connection to the house. I think they are to be spaced 6 feet apart and connected w/solid bare wire.
 
Breakers on one side? might be a neutral buss on each side, I wonder if the tie between the two busses is loose. For that, you might be able to tie DMM to ground (service in), then to neutral on bad side. Kick on a heavy load. Should be little voltage rise on neutral inside the box.

Hard to capture transients unless if your meter has hold feature, but I suspect heavy loads will show a voltage drop somewhere.
I could video the Fluke 77 and watch the digits flash and the bar move, and I think the one I have at home includes a min/max function. I no longer have the Simpson 260 analog meter. And for the life of me, wish I still had one. I ended up chucking mine in the trash, as it was truly falling apart and beyond practical repair. Maybe I could pick up a halfway decent analog replacement.

The interesting thing is, it really does not take a heavy load to generate this problem. I am fairly sure the gas dryer only pulls a few amps. I'll put the Kill A Watt on it to check starting loads. The motor is a tiny thing. And the igniter is prob about 400 watts max.
 
FWIW and in keeping with the comments above, FPL now requires at least TWO ground rods at the meter connection to the house. I think they are to be spaced 6 feet apart and connected w/solid bare wire.
It would be a relatively simple matter to install another (new) ground rod or two. They are adjacent to the panel and driveway, easy access. The installation looks healthy, but it is worth checking out.
 
I am not home, mama (wife) is troubleshooting over the phone. We are having trouble with one leg of power. When the 120V gas dryer kicks on, the UPS’s in the den go a-beeping and the internet drops out for a sec (despite being on a UPS) Voltage sags to 60, then recovers. Same with the microwave and the 120V air compressor won’t start Unless empty. I did change the start and run caps in the compressor motor, thinking that was a separate issue. But it seems not.

You have a loose neutral somewhere at junction (buried) or transformer (above ground)
 
It would be a relatively simple matter to install another (new) ground rod or two. They are adjacent to the panel and driveway, easy access. The installation looks healthy, but it is worth checking out.
AND easy to drive into the "soil". When I asked for pointers on driving one near my pool transformer, the guy at HD said to clamp a pair of vice grips on the top before hitting it. He said if you don't, it may drop out of sight! :D
 
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