mystery circuit fault

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Old 12-16-10, 09:36 PM
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mystery circuit fault

We're having new floors put in and today suddenly two breakers blew while the workmen were here. I can't reset either breaker.

One outlet is a standard 2-wire GFCI outlet, when I removed the outlet and put an ohmmeter across the red and white wires, it reads a short.

The other outlet is the washing machine/refrigerator circuit (two outlets on opposite sides of the wall) that's an oddly wired 2-phase outlet (one red wire, two whites, with one of the whites carrying current). I disconnected the outlet there and there's no short from the red wire to either white wire, but both white wires do read shorted to ground.

I don't know enough about this stuff to understand what might be going on here. I suspect that the workmen might have driven a nail through the white wire that was carrying the load, would this explain why the breakers for both circuits are not resetting?
 
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Old 12-16-10, 10:37 PM
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We're having new floors put in and today suddenly two breakers blew while the workmen were here. I can't reset either breaker.
Were they using a large floor sander or large saw?

One outlet is a standard 2-wire GFCI outlet,
Can you reset it? What do you mean by standard 2-wire GFCI outlet?

put an ohmmeter across the red and white wires, it reads a short.
Don't do that again. You could of damaged your meter or hurt your self. Normally you only use it to check voltage. There are exceptions but they must be done only after checking there is no voltage.

The other outlet is the washing machine/refrigerator circuit (two outlets on opposite sides of the wall) that's an oddly wired 2-phase outlet
Not 2phase.
one red wire, two whites, with one of the whites carrying current).
Explain what you mean by white carrying current. Are there black wires also?

I suspect that the workmen might have driven a nail through the white wire that was carrying the load, would this explain why the breakers for both circuits are not resetting?
Yes if it also pierced a black wire or just pierced a black wire and touched something grounded. Or maybe they shorted the two branch circuits together.

would this explain why the breakers for both circuits are not resetting?
It could. If you feel comfortable working in the breaker box, turn off the main breaker, remove the cover, and then remove the wires from each of the branch circuit breakers you can't reset. Turn on the main breaker and test if you can now reset the two problem breakers. Caution there are exposed electrified metal surfaces in the breaker box even with the main breaker off. Be very careful.

I would suggest politely asking the floor installer to have a licensed electrician check it out This may be above beginner DIY skills and if they caused it it is their responsibility.
 
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Old 12-16-10, 11:13 PM
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Originally Posted by ray2047 View Post
Were they using a large floor sander or large saw?
Yes. Could they have simply overloaded something?



Can you reset it? What do you mean by standard 2-wire GFCI outlet?

No, I can't reset the GFCIs. But I read that newer GFCIs do not reset if there is no current.

Don't do that again. You could of damaged your meter or hurt your self. Normally you only use it to check voltage. There are exceptions but they must be done only after checking there is no voltage.
The power was off at the breaker, so what danger is there to checking continuity?


Not 2phase. Explain what you mean by white carrying current. Are there black wires also?

No, just one red wire and two whites. As I recall from when I installed the GFCI a long time ago, if I measured across the red wire to one white, I got 110V. But if I measured across the red wire to the other white, I got 220. I was told that this was because it was a 2 phase circuit. This gets beyond my ability so I don't know for sure.




I would suggest politely asking the floor installer to have a licensed electrician check it out This may be above beginner DIY skills and if they caused it it is their responsibility.

Yes, this is beyond what I feel comfortable doing. I will call an electrician, but I am just looking for as much information as possible. Thanks.
 

Last edited by ibpooks; 12-17-10 at 07:54 AM. Reason: fixed quote tags
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Old 12-17-10, 12:07 AM
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Originally Posted by toecheese View Post
We're having new floors put in and today suddenly two breakers blew while the workmen were here. I can't reset either breaker.

One outlet is a standard 2-wire GFCI outlet, when I removed the outlet and put an ohmmeter across the red and white wires, it reads a short.

The other outlet is the washing machine/refrigerator circuit (two outlets on opposite sides of the wall) that's an oddly wired 2-phase outlet (one red wire, two whites, with one of the whites carrying current). I disconnected the outlet there and there's no short from the red wire to either white wire, but both white wires do read shorted to ground.

I don't know enough about this stuff to understand what might be going on here. I suspect that the workmen might have driven a nail through the white wire that was carrying the load, would this explain why the breakers for both circuits are not resetting?
I think it will be wisest to call in the electrician due you mention workmen were working on the floor what equiment they did use to work on the floor and did they used the nail gun or screw gun ??

If the latter two items just call in electrician they can able find the short and get it fix

I have ran into this kind of situation before and one flooring contractor did hit few cables and I end up replace quite few of them and that flooring contractor have to pay my time to fix this up.

So I am not really suprised if they did ran super long nail or screw that useally the curpits.

Merci.
Marc
 
  #5  
Old 12-17-10, 05:06 AM
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Fault

Do you have access to the under side of the floors being replaced? If so, look for nails driven into electrical cable(s).
 
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