We are renovating a large building with three separate services,Yesterday we shutdown service "A" and installed a temp service to feed all sub panels while we install the new switchgear .while the power was down to service "A" only one feeder had 99v from the DMM on a,b,c and neutral to ground each. Each of the wires were disconnected on each end except the neutral. I could not find out why I was getting the stray voltage.when all of the temp feeds were finished I have 3 single pole 20a breakers from two different panels that keep tripping and the surge protectors on the wall receptacles were fried. One other electrician said when one of the breakers were turned on there was an arc at the transformer.This service is a 277/480 with a y 120/208 system. Any thoughts?
One building three services, stray voltage
- Thread starter Csdub3
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- Licensed Electrician
Welcome to the forum.
I don't know that the 99 volts is a problem or just phantom voltage and I don't think that it has anything to do with the tripping breakers.
Do you have normal voltage at the panels now? If so then I would concentrate on finding the fault that's tripping the 20A circuits. I'm not sure what to say about the surge protectors except they're fried so get rid of them for now.
I don't know that the 99 volts is a problem or just phantom voltage and I don't think that it has anything to do with the tripping breakers.
Do you have normal voltage at the panels now? If so then I would concentrate on finding the fault that's tripping the 20A circuits. I'm not sure what to say about the surge protectors except they're fried so get rid of them for now.
voltages elsewhere are all fine and rotation at every panel is correct.
I think there might be two neutrals tied together from one of the other services?
i was getter my the 99 volts with the wires of the sub panel hooked up to nothing at all besides the neutral that was still landed in the panel.
I think there might be two neutrals tied together from one of the other services?
i was getter my the 99 volts with the wires of the sub panel hooked up to nothing at all besides the neutral that was still landed in the panel.
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- Placerville, CA, USA
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- Retired PV System Designer
It looks like phantom voltage. All that would be needed to cause that would be hot wires from one service running in the same raceway with wires from the disconnected service.
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