110v line now registers 220v

newjerseybtJuly 12, 2011

My sister's neighbor came home from work and noticed his CFL bulbs in L.R. were not working. He replaced one with an incandescent and that blew immediately. Checking the line voltage at the lamp plug it read 220v instead of 110v.

Could this be a combination of problems such as as a miswire when the house was built or a combination of a miswire and/or a lost ground after a lightning strike? There is possible evidence of a lightning strike.

An electrician was called and all they could find was a burn't out basement pump motor but that motor was previously running on 110v.

The homeowner then said the power at the light plugs returned to 110v when the motor was replaced but I suspect the problem has not been corrected but hidden by the continuity/conduction of the motor windings.

Anyone ever encounter such a problem?

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Open neutral somewhere.

    Bookmark   July 12, 2011 at 9:55PM
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"Open neutral somewhere."


The loads on each leg are dividing the 240 V based on their impedance.
Since the loads are not identical the mid-point is not 0 V producing a pair of 120 V feeds.

The voltage on one leg can approach 240 V while the other will be almost zero.

This is an immediate fire and safety hazard.


    Bookmark   July 13, 2011 at 11:05AM
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Thanks for quick responses. I will forward your responses to homeowner immediately!

    Bookmark   July 13, 2011 at 4:44PM
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