What to look for?

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nizak

Senior Member
I got a call from a homeowner who is telling me that the utility somehow energized the neutral conductor with 120V and ruined several electronic items in their home.

The utility is not denying that it happened. The owners insurance company wants to have the wiring checked to make sure there is not additional damage that is unseen at this point.

I really don't know what to look for. NM cable is rated for 600 volts so I don't see damage occurring that way.


What else is there to look for?

Suggestions appreciated.
 
Most likely no further damage to internal wiring as you’ve said, just check all the equipment in the home for damage. Of course this is just visual so you can’t vouch for something that may crap out in a couple weeks because of some weakening effect, And I would state it as such.

What was the power company doing to accidentally put 120 on the neutral?
 
Depending on how they apparently miswired a transformer, some 120v devices and breakers undoubtedly saw 240v.

aside from the customers equipment, I would check all GFCI and afci devices, and all dimmer switches for proper operation. anything that could have been damaged from over-voltage or reversed polarity. I cannot think of any potential problems with the wiring from such an error.
 
I had one of those a while ago, everything metered out fine, made multiple visits, drove me nuts....etc

Came to realize the tape had worn off the very old OH splices & were clicking together on windy days

~RJ~
 
Probably no further damage other than anything electronic or with a digital display is now toast. Damage would be somewhat similar if you lost the neutral at the utility pole.
 
mopowr steve said:
Most likely no further damage to internal wiring as you’ve said, just check all the equipment in the home for damage. Of course this is just visual so you can’t vouch for something that may crap out in a couple weeks because of some weakening effect, And I would state it as such.

What was the power company doing to accidentally put 120 on the neutral?
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I agree, most damage should already be obvious. Minor damages that may have occurred may not show themselves for years, and by then no one will know any different.

What did they do - maybe miswired transformer connection, or service drop/lateral connection. (Service drop not so likely simply because neutral is likely a bare conductor, but not impossible).

They also can on occasion get high leg on the wrong lead on high leg services or wrong rotation.

Most are pretty good at pulling meters, opening switches, etc. and verifying proper voltage, rotation (when applies) before installing meter or closing switches though.
 
It's also possible the actual situation was an open neutral which, as we have discussed ad nauseu, can act as an energized neutral under load.
 
Tony S said:
You could “Megger” all circuits, then you can give the insurance company measured values. If US insurance companies are anything like the UK they’ll try to wriggle out of paying.
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I agree that they will try to get out of paying claims, but megging something that is working is sort of useless information for proving any damages if you don't know what the results would have been before the abnormal voltage incident occurred.
 
Tony S said:
You could “Megger” all circuits, then you can give the insurance company measured values. If US insurance companies are anything like the UK they’ll try to wriggle out of paying.
Click to expand...

I have found insurance companies are generally pretty good at paying out claims.

Something like this could be lightning, could be POCO issues, could be failed wiring or equipment. I can kind of understand not wanting to pay out unless it can somehow be shown as a legit claim that is actually covered by the policy. A key part being that the policy covers the loss.
 
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