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With the main house breaker turned off, I have electrical continuity between the hot lug at the service entrance and the neutral bus in my service panel.

I also have electrical continuity from neutral to one leg of the service.

Does this indicate that I have a bad main breaker?

  • How are you determining that there is continuity? If there were, that would be a dead short and your main service wires would quickly overheat and catch fire and/or blow a fuse at the street. – Hank Sep 30 '14 at 2:22
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    Try turning off all the branch circuit breakers, and test again. Or disconnect the ungrounded "hot" and grounded "neutral" conductors from the panel, and test them while not connected to the panel. If you find that you still have continuity, you'll want to find the short before connecting the service (otherwise the service provider is going to be really mad at you). – Tester101 Sep 30 '14 at 9:33
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Since you are not connected to the grid yet, the wires from your mast a probably just hanging or coiled up, and the ends are touching. Check those wires.

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If anything is turned on -- a light, the heating/ac system, whatever -- that's a path between hot and neutral. Motors are a near short circuit for dc; their load is almost all inductive. Resistances in parallel decrease. So a static continuity measurement may be misleading.

Turning off all breakers, and turning them back on one at a time, should help you isolate the path(s) being taken.

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To start with you never test for continuity on a live circuit depending on the type of tester you are using you could damage the tester or yourself or both. By calling it the "hot lug" it sounds like that is what you are doing. If you are testing from one of the phase wires on the load side of the main breaker with it off to the neutral you will get a reading if any of the branch circuit breakers are on and connected to loads. Turn off all of the breakers and check again it should read no continuity.

  • It's a new house. No power to the service, no loads. With the breaker off I can measure continuity from one of the service legs before the breaker across to the neutral bus in the box. I stumbled across this when I went to check for line damage. There service comes off a mast to a meter. From meter to a power box with a breaker. 250 underground cable to the main panel in the house. If the main breaker is off there should be no connection between either "phase" wires before the breaker across to the neutral? I'll check with all breakers off in case of a bad wiring job. – G Woody Sep 30 '14 at 4:04
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    Is the meter installed? – user24125 Sep 30 '14 at 4:07

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