spiking voltage

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zapped 1

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recieved emergency service call for burnt wire smell arrive on scene no smell start checking panel no obvios signs of trouble put tester on a phase to nue 153v b phase 96 turn off breakers 1 by one get to ref voltage balances out repeat steps and spikes again on nook bed 2and3 master circuits no common neu circuits in panel try moving thing around still same problem different circuit my gut tells me there is a nuetral problem somewhere but why so many different circuits checked attic no melted wires ripped apart many joints still cant figure out neeeeeeeeeeeeeeed help this is a challenger 150 resi application house is 10 yrs old no work done recently could it be the main ????????? checked poco side 122/122 volts with main off any advice even had boss man out he is stumped also
 
zapped 1 said:
.........checked poco side 122/122 volts with main off any advice even had boss man out he is stumped also
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If you turned the main back on, your voltages would jump out of line again. You need the loads on both sides of the service to induce the voltage variations.
 
zapped 1 said:
checked poco side 122/122 volts with main off any advice even had boss man out he is stumped also
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I think you are probably going to need to leave the main on ( put a load on the system ) and check voltage on the line side the meter socket to see what you get ( each phase to neutral).

When a neutral opens it changes what is normally a parallel circuit into a series circuit and you need the load to provide differences in resistance. It's the voltage drop across the different amount of resistance that gives these weird readings. Voltage drop is not constant in a series circuit.
 
zapped 1 said:
checked poco with main off good voltage turn main on things get crazy i dont believe it is a poco problem how to find open nue bob by box???
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I think you need to call the power company and tell them they have a problem. If voltage is crazy on the line side of the meter socket.
 
zapped 1 said:
recieved emergency service call for burnt wire smell arrive on scene no smell start checking panel no obvios signs of trouble put tester on a phase to nue 153v b phase 96 turn off breakers 1 by one get to ref voltage balances out repeat steps and spikes again.
Click to expand...

That nice burned wired smell is from the sensitive electonic equipment being destroyed.

The good thing is that if you are there and the power company admits that they caused the problem it's possible for the homeowner to put in a claim against the power company for damages and even collect for the cost of the service call. Check everything that had micro-processor based controls and any ballast or small transformers ( almost every thing these days). Even the the door bell x-former.
 
First of all If you ever suspect an open neutral you never turn all the breakers on, you can do more damage doing this and might even cause a fire!!!

Only turn the main back on after you have turned each branch circuit breakers off!!!

Load only one leg of the panel by turning on only the "A" phase single pole breakers, make sure which leg they are on by the type of panel it is, some of the older panel manufactures (like Zinco) can have two "A" leg breakers side by side, so unless you are sure check continuity with the main off to see which breakers are on "A" leg

And only do this when you know there is nobody around anything that is connected to the grounding of the service!!! make sure no one touches anything metal, as the lost neutral will cause the voltage on the grounding of the house to rise to 120 volts to Earth when you preform this test, so don't leave the main on for long!!! have someone at the ready to test the neutral voltage to the "B" leg at the main and at the meter both line and load side, to the wires not the terminal.

many times the POCO can miss this if not loaded like the above when they arrive to do their test, so try to be there when they are.

Anytime you have an over voltage symptoms (lights getting brighter, electronics frying), Kill the main ASAP!!!, and only turn it back on to test as in the above, but only after you have turned all the branch circuit breakers off.

also make sure there is no boot legged loads ahead of the main!
 
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