I'm in electrical classes and we are hooking up a 240v trainer. Last year the trainer worked fine. When connected to power there is a 120v light bulb that lights up to show that power is on. Yesterday we plugged it in and the light would not come on, but we had 240v through the meter. This is being connected on a new panel box that is 120v/240v, no stinger. Power coming into disconnect is reading 126v on L1 and L2 to neutral or ground, 246v between them.

I decided to work on just getting the light to work first, (yes the bulb is good and the light base is good). I hard wired it out of the panel box using L2 and Neutral and wire nutted the L1 off. Turn power on, no light. when I check the voltage at the light I get 0. From the breaker I get 0 on L2 and 246v on the L1. When the load is disconnected, at the breaker I read 126v from L1 to Neutral or ground and 126v from L2 to neutral or ground. I did do a continuity check from the disconnect to the panel box. When checking the L2 it beeped on L2, Neutral and ground. It is very strange, and I have been told several times that it is impossible to get 240 from one leg, but it is happening. All I can come up with is that L2, neutral and ground are somehow connected because of the continuity test. However wouldn't it trip the breaker?

  • You have continuity on L2 to Neutral and the breaker didn't trip? Is there continuity between Neutral and Ground? Perhaps the breaker is going bad and you are shorting somewhere? If L2 is shorting to L1 then that would explain 240V reading on L1. – maple_shaft Dec 13 '12 at 19:37
  • Did you wire up the service drop (the cable feeding the disconnect) as well, or is that supplied to you by the teacher? This might be caused by a problem before the disconnect, and the teacher could be testing your knowledge. – Tester101 Dec 13 '12 at 20:19

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