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Had an instance before when I had a voltage while running on a treadmill. I flipped all the breakers and it seem to work again for a month and now it is back and now when we use a high load appliance like the microwave the voltage drops.

I tested all the breakers by adding a load and it seems it’s on one leg. And I tested the lugs and the voltage did drop with a load. Unfortunately the tested I am using isn’t digital and doesn’t display the actual voltage but the 120 light is completely off under load and only the 24v is light. The 120v light comes back on when the appliance turns off.

Is there a problem in the house on one of the circuits? Or does the drop on the lug indicate a problem before the breaker panel?

Thanks in advance for any advice.

Edit: I picked up a digital multimeter and now under normal loads the one leg reads 125-126 and other 115ish. With the microwave on it goes becomes more unbalanced 130v one lug to 110v on the other

Edit2: with the washer a full when agitates(using the motor) voltage dropped to 97v on one leg and the 140v ish on the other. Again coming in from the service line to the main breaker. That seems to be getting too much so I called in with the PoCo reporting a partial outage.

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  • Can you get a better tester that displays the actual voltage?
    – ThreePhaseEel
    Commented Jan 19, 2019 at 17:04
  • Getting one now
    – ecco88
    Commented Jan 19, 2019 at 17:18
  • If you keep turning off loads/circuits, do the legs start to balance each other out?
    – ThreePhaseEel
    Commented Jan 19, 2019 at 19:41
  • Actually turning off the breakers results in little or no change. One leg is 125-126 other now is 116-117. I literally had every breaker on the one leg turned off. Should I rearrange the breakers to see if it changes? Is it an issue on one of the branches that is causing the problem. Seems more like a service line issue.
    – ecco88
    Commented Jan 19, 2019 at 20:44

2 Answers 2

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I bet I'm in a race with ThreePhaseEel to post this.

Call your power company NOW and report an outage

Specifically, a lost neutral.

My company came out in less than 2 hours on a Saturday. It will be free, and most likely they'll find a problem on pole or service drop. Just the same, helps to have the front off your service panel.

As you know, American houses get 240V power, but appliances are 120V, or half. What keeps the center centered is the neutral.

If you lose neutral, then each leg becomes biddlebooble, but the two legs still add up to 240V pretty much on-the-money. That means when one is under 120V, the other is over by the same amount. And the high leg can switch. This is what makes it an emergency: the significant overvoltage can blow out appliances and start fires.

At this point it seems like a partial failure, but it's likely to become a total failure soon. My power company just fixed one of those, our neutral was flapping in the breeze, but a neighbor's hot was nearly worn through from a bad termination on the pole and years of cable swaying just wearing it down.

Also, total neutral failures will act like partial failures, because they are still able to return some neutral current via earth to the transformer's ground strap.

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  • 1
    Thanks Harper. I went and got a digital meter to get actual readings . Are my actual readings delta (125-115) large enough to call the PoCo?- Should I call the poco and say I think there is a lose neutral? My meter is inside but maybe it is even before the meter - maybe on the drip loop outside?
    – ecco88
    Commented Jan 19, 2019 at 20:46
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    If you can load it up with additional loads, and the center point moves more but the endpoints don't sag, that's a lost neutral. The drip loop is a likely candidate, the poletop is even more likely.
    – Harper - Reinstate Monica
    Commented Jan 19, 2019 at 20:57
  • Thanks for posting this. I was annoyed at my apartment management for ignoring mine being at 110 with my ACs on. Today it was at 108 with everything OFF and 100 with one AC on! I was looking it up out of concern for my own stuff, but if me being at 100 puts one of my neighbors at 140...you can bet I called the power company right after reading that.
    – Vanessa Phipps
    Commented Jun 1, 2023 at 16:23
  • @Vanessa We have 120V at my winter cottage; when I went down my neighbor went up. However, the vast majority of housing stock in North America gets both poles, so the 140V may be at some of your sockets! Upside: it's usually a power company problem on their equipment, not a landlord problem, so it can usually be fixed without landlord complications "getting in the way".
    – Harper - Reinstate Monica
    Commented Jun 1, 2023 at 18:54
  • @Harper-ReinstateMonica My apartment only has 1 circuit...which is its own problem.
    – Vanessa Phipps
    Commented Oct 14, 2023 at 23:46
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On your main breaker, Are you checking at the connection of the service to the breaker or after the breaker? If after the breaker try turning all loads off and flip the main breaker 10+ times, this can reseat the hammers in the breaker. If measuring prior to the breaker call your utility and tell them you are having a service problem.

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    Tested on the lugs so before the main breaker.
    – ecco88
    Commented Jan 19, 2019 at 20:25

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