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Old 07-17-2012, 10:24 PM   #1
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Neutral Energized


I just rewired a cabin that is seldom used. New panel and all new wire. As its seldom used, we have a habit of turning off all the breakers when we leave. The owner recently attempted to turn on a breaker and fire flew but did not trip a breaker. After he told me, we both went to try to find the problem. I turned on each breaker one by one and checked the appliance they were feeding. Everything worked as it should. I then turned off all breakers to check my wiring. I couldn't find any problems. I then attempted to turn on a breaker again, and sparks flew as the owner had described. Quite by accident I realized that with all the breakers turned off, the main neutral is hot.
As a secondary measure, I had another electrician check my work and meter all the circuits. His result was, no problems.
After doing some research, I find a rare occasion where the power company's neutral becomes energized for whatever reason. The main coming to the meter base is buried from a pole nearby. There is no apparent problem that I can see. I have also heard of one case where a transformer became shorted and energized the neutral.
Anybody else here ever experience this before?

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Old 07-17-2012, 10:41 PM   #2
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Neutral Energized


You should call the power company asap before you start frying stuff.

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Old 07-17-2012, 10:54 PM   #3
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Neutral Energized


Yes, thanks for your answer. But my original question was , "Anybody else here ever experience this before?"
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Old 07-17-2012, 11:16 PM   #4
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Neutral Energized


i have expierienced that and found that the grounds tied to the neutral, although up to code, were not enough and didnt properly ground the panel. sometimes rodents chew through copper on uninhabitted homes or cabins. in my case, I could drive a large screwdriver into the ground, wet it without saturation and find voltage from my panel ground to the screwdriver. I had a fault in the house. the pole ground wasnt working well either with a poor ground connection. be carful checking grounds on the pole one bad transformer could spell disaster for the guy making the connection to ground. goodluck
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Old 07-17-2012, 11:55 PM   #5
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Neutral Energized


Your description isn't specific enough to say whether anyone else has experienced exactly the same condition before. We would have to know what voltages and currents are present where to make a definite diagnosis of what the problem is. But based on the description, it sounds like the utility's primary neutral may be compromised, thus making your earth grounding system the return path for the utility's 7200V (probably) primary current. Definitely call the power company ASAP.
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Old 07-18-2012, 05:37 AM   #6
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Neutral Energized


There is at least one post a day on this type of situation.
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Old 07-18-2012, 10:27 AM   #7
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Neutral Energized


The utility pole primary neutral, secondary neutral, and ground are one and the same This consists of a usually bare wire from pole to pole halfway up together with ground wires going down, say every other, pole to ground rods. The 120/240 volt lines (secondary lines) from transformers to homes may be wrapped around this bare wire on the way to some of the houses.

If the the pole neutral/ground system is breached, then you can have the problem of primary current using the various home service neutral/grounds and ground rods as a return, passing through perhaps a few hundred feet of earth, and getting back up the grounding electrode at the bottom of a different pole.

The earth is not that great a conductor so if the above problem should happen there will be almost no voltage drop along the neutral/ground/messenger from pole to house and a significant voltage measurable between house panel neutral bar and the ground wire out at a pole.

In some rural areas where the total number of amperes of (7200 volt or whatever) primary current is small there is no neutral from pole to pole all the way back to the substation. The primary current relies on earth return vaguely following the parade of poles back to the substation. There is still a ground/neutral from pole to pole (wrapped with the 120/240 volt secondaries) only as far as any given transformer serves homes.

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Last edited by AllanJ; 07-18-2012 at 10:48 AM.
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