just wondering why I would have 170V to ground on my home run at a light box when at the breaker it reads 118V to ground. What is the reason for this voltage spike?


  • 2
    The #1 way I know for that to happen is a lost neutral a) at the pole, b) in the meter/panel, or c) in a multi-wire branch circuit. Look for 120V circuits on the other leg having lower than normal voltage. This is an emergency; deal with it immediately or power down all 120 and 120/240 loads. Nov 8, 2019 at 19:41
  • 2
    Possible duplicate of Panel breakers are alternately 90 V and 140 V Nov 8, 2019 at 19:56
  • The bad news is that if voltages of both legs in the panel are fine then it's likely not the power company's problem.. meaning you're on the hook to pay to have it fixed as well as any equipment that gets damaged. But it is an emergency: equipment subjected to out-of-spec voltages can fail in spectacular and fire-igniting ways.
    – Greg Hill
    Nov 8, 2019 at 20:35
  • I would unplug everything that's on that circuit until you find and fix the problem. The fact that it's OK at the breaker leads me to believe it's an indoor problem. Has anyone done any electrical work there recently???
    – JACK
    Nov 8, 2019 at 20:53
  • is this without any load at all?
    – dandavis
    Nov 8, 2019 at 20:58


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