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Most of the outlets in my workshop stopped working last week. My 220V outlet, a dedicated outlet for a compressor, and the garage door are still working. The shop has a dedicated circuit box, which is a GE sub-panel from the main panel at the house.

I unscrewed the front panel and measured the voltages of the 2 buses using my multi-meter and found the right bus measures 120V, but the left one measures around 20V and bounces around. All the breakers connected to the left bus are the ones that stopped working. The box has it's own double pole main breaker rated at 100A.

Could it be that one half of that breaker is bad? What would be the most cost effective way to troubleshoot the problem? I would like to avoid buying all new breakers for the receptacles if that is not the problem.

  • I take it these readings were taken at the main lugs of the subpanel, no? – ThreePhaseEel Mar 28 at 19:20
  • Yes, one lead on the buses themselves and the other on the ground bar – Fiver Mar 28 at 19:24
  • Take the reading in the main panel. – JACK Mar 28 at 19:40
  • Does everything work in your house? – JACK Mar 28 at 19:41
  • @Fiver -- can you open the main panel and take readings from the lugs of the subpanel breaker to ground, please? – ThreePhaseEel Mar 28 at 20:08

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