Why causes all the lights to dim and then brighten repeatedly?

My house has a problem with dimming lights, appliances, etc. For no apparent reason, all the lights will dim, appliances (fan, microwave, etc) will slow down, etc. It is not due to a single circuit, I’ve isolated various circuits via breaker panel and the lights still dim and then brighten. Check the voltage on the main feeders during one instance and one leg was 85V, the other 155V (this was the extreme, usually its around 130/110). Flipped a couple breakers and lights returned to normal and voltage read 122/122. Next time they dimmed, turned off the same breakers but the lights stayed dim. I’ve tried turning off all 220V appliances, turning off the circuits that use aluminum, etc, but the problem still remains. Its as if the problem is with power coming into the house.

Electrical system details: Pushmatic Service Panel (160amp), 1/2 the circuits are aluminum, other half copper. 3-220V appliances / 10 15-20A 115V circuits.

Does anyone know what would cause this?


I have an electrician coming on Tuesday, just trying to arm myself with a little knowledge before he shows up! I was an electrician in the Navy and am fairly familiar with electricity, but this one has me baffeled!

At first I thought it was a problem with the aluminum circuits so I completely disconnected all the aluminum cables from the breaker but the problem remained.

I really think its a power company problem, just wondering if anyone else had this issue and what solved it!

9 Answers

  • J84
    Lv 4
    1 decade ago
    Favorite Answer

    it sound like you have to many things on one circuit and you are over loading it that can be a dangerous thing you should call a electrician.

  • 1 decade ago

    You have two power legs coming into your house from the power company. When you have a short in the one power feed with the ground wire the result will be no power at all on that power leg with no 220 systems working at all. When you have a short between the the two power feeds the result will be one leg will have higher voltage and the other will have lower voltage. You should have 230 or 240 Volts coming into your house running in parallel with equal amounts voltage on each each leg. When they short together the two power feeds run in series and the voltage will increase thus your readings that seem to be fluctuating.

    With half of your panel being aluminum and half copper, you automatically have an unbalanced load even if your circuits are balanced since copper is a better conductor of electricity. Your power company will more than likely trace out this problem for you. My experience is that they generally won't even charge you. Time to do a panel upgrade! Good Luck.

  • 1 decade ago

    do you have problems with both the copper and aluminum circuits? or just the aluminum ones? if just aluminum, bad connections. if both, the problem might be where the mains connect. do you see corrosion on any of the wires at the terminals? if this all appears good then the trouble is with the electric company supply. call them and have them check the supply to your house for you. good luck, and have a happy new year!!

  • 1 decade ago

    I had this same problem every time that my heat pump kicked on. I had a bigger capacitor put on the condensing unit of the heating and cooling system and it still happened a little. Then AEP replaced my transformer on the pole in my front yard and the problem is fixed. Just a start.

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  • 1 decade ago

    I agree with the previous poster, and recommend that you contact your local electric company. You should not be having such extreme voltage swings, and may be a faulty transformer or bad line connection in your neighborhood.

  • Anonymous
    5 years ago

    Sounds like a loose ground .make sure every connection is tight. Try moving the connections around by hand and see if something is slipping. Its not your belt It is usually around whatever was replaced

  • 1 decade ago

    #1 contact your utility company

    #2 contact a licensed electrical contractor

    #3 this is NOT a do it yourself project

  • 1 decade ago

    Have you tightened the connectors where the incoming feeds are?

  • Anonymous
    1 decade ago

    its power supply problems

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