Surge Question

I have been having electrical work done at my home by a licensed electrician. In the course of the work a power surge occurred, burning out a TV, timers for my sprinklers, a telephone and two surge protectors in an adjacent guest house (the main house is under construction and has no electronic equipment in it).

Sometime prior to the surge (24 hours?) the carpenter mentioned to me that a neutral wire in an outlet was disconnected, and the electrical workers were trying to locate where the disconnect occurred, but that I should mention it to the electrician to ensure that it was fixed. Which I did and it was.

In investigating the cause of the power surge, the power company, not knowing anything about this, told me that the power surge occurred because of a neutral disconnect which would cause the 110 wire to arch to between 60 -240 volts. So it seemed like the electrical people made a mistake and was the cause of the surge and my loss.

In speaking with the electrician about this, he says that he does not believe this to be the cause. He says in rewiring switches and receptacles, the neutral wire is often disconnected and no arching occurs.

I need someone who understands these things to help me understand the neutral wire issue so I can decide whether I should pursue the electrician to cover at least part of my loss. Can you help me?

Thank you,
hb

 

Power is supplied to your home in the form of 240V 'split in half' by a neutral. If you were to disconnect the neutral, then the full 240V would be shared by whatever loads were connected to the two halves of the supply, and the voltage on each half could range anywhere from 0V to the full 240V, depending upon the balance of the loads. This is where the potential 240V comes from.

But a break in the neutral only causes problems 'downstream' from the break.

If the broken neutral is an unshared neutral in a receptacle on a single branch circuit, it could not cause 240V anywhere, and could only cause 0V on that single circuit.

If the broken neutral is a shared neutral in a single 'multi-wire' branch circuit, then it could only cause problems on the two single phase circuits associated with that multi-wire.

If the broken neutral is the main neutral feed to your house, then it could cause problems for the entire house.

If the broken neutral is the neutral connection of the power company transformer, then it could cause problems for all the houses that are connected to that transformer.

There is not enough information in your post for me to form an opinion on who did what where, but the above should help you figure out where the problem occurred, based upon which circuits were affected.

-Jon

 

Hopefully when the electricians were working on your circuits, they turned off the breakers, thereby eliminating any type of open neutral problems. As long as they hooked them up correctly before turning back on the breakers, of course.

 

Thanks your comments were helpful. Now at least I can ask more questions.
hb

 

Opps. I ment to thank Scott, but wrote Steve.