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I have 240 volt service to my house. I have a 50amp dual pole breaker feeding a sub panel 60 feet away. At the breaker I have 120 volts on each leg. At the end of the sixty foot run, L1 has 100 volts, L2 Has 140 volts. This is measured under no loads, just the end of the wires. I swapped the wires and the readings followed the Wire swap. I’m thinking wiring issue. Does this sound right to everyone?

Update: Thanks everyone for the info. I picked up 100' of new copper, and bypassed the neutral in the circuit, that fixed the problem. So I'll be pulling it through conduit tomorrow... possible disaster averted!

  • are you measuring the voltage under load? – jsotola Jul 7 '18 at 19:13
  • Which end did you swap the wires at? – ThreePhaseEel Jul 7 '18 at 19:26
  • At the breaker main panel in house, the suBpanel is 60 ft away for a storage building – Marcus R Hall Jul 7 '18 at 19:27
  • This is measured under no loads, just at the end of the wire run – Marcus R Hall Jul 7 '18 at 19:30
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    When they are not correct but do add up to 240V, that's a neutral problem. Go over your neutrals with a fine tooth comb. – Harper Jul 7 '18 at 20:27
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It's an open neutral

This sort of voltage imbalance is symptomatic of one thing and one thing only -- an open neutral somewhere. Fix the neutral issue, likely at a termination although it could be a damaged neutral on a direct bury cable or the likes, and the problem will go away. Keep the shed turned off at the feeder breaker until then though, as open neutrals tend to be rather...incendiary to electrical equipment.

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