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Discussion Starter · #1 ·
To begin with, this happened several years ago. The house in question is a 45 min. drive away. So no im not going back and what info i give in this post is all i have.

HO calls and says Roofer says they are getting shocked between the new tin roof they are installing and the earth. First thought, nails/screws are too long. I call the roofer and have a friendly conversation (i purposely kept it that way, i want him on my side). Meanwhile i find it hard to believe.

Go to the site, get the vom and an aluminum ladder (on purpose). Meter shows about 60VAC from roof to ladder. Again I find that hard to believe, so i put my sweaty arm on the edge of the roof and the ladder, sure enough it stings a little. Now im on the hunt, i did my best to check every penetration of the roof in some way.

Eventually im at the service entrance and looking for amp differences between phases and neutral in the primary panel, cant find it. I cut the main breaker off, roof is still hot. Finally I pull the meter, still there .....

Go to the natural gas supply line and check for unusual voltage, go to the gas meter and unroll 250' of 12-2G romex for a test jumper back to the house. cant find it.

In desperation to get the roofers back on the job, I drive a ground rod at the edge of the lake (house is located close to a lake/ aka Lake house around here) and connect my jumper to the roof.

At my request roofer calls to let me know every thing is fine, of course HO does not want that eyesore hanging from the roof, so I remove it after the roofer is done.

Long story short ... I still dont know how this happened. Dont forget, I pulled the meter and roof was still hot, I examined the service drop very carefully, it was not touching the roof.

I eventually convinced the HO (a nice lady) that it was the fault of a new cell phone tower about a 1/4 mile away, and therefor was something akin to static electricity. Im not sure if that is possible, but thats my story and im stickin to it LOL


Any ideas ????
 

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Service properly grounded otherwise? Didn't get a tingle off the service mast?

Any HV transmission nearby?
 
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Did you physically go into the attic and check for romex stapled to the rafters that was compromised?
 

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How about an energized metallic plumbing vent?

Any other penetrations?
 
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Is it a areal service? could the roofing material have rubbed the SE cable? I ask because you said you pulled meter (meaning no voltage from meter to load center to house)) and still had the 60v potential.
 

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If you opened the main, and verified it really opened, then it couldn't be a nail or other fault to the branch circuit wiring, it had to be something upstream of the main. If it wasn't in the aerial conductors where you could examine, maybe inside the mast or something.

Another possibility is that there's a problem with a neighbor, a neutral problem on a neighbor's service, or something with the power company. Checking to see if there was a problem anywhere other than the roof would have been helpful.
 

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Discussion Starter · #12 ·
Is it a areal service? could the roofing material have rubbed the SE cable? I ask because you said you pulled meter (meaning no voltage from meter to load center to house)) and still had the 60v potential.
If you opened the main, and verified it really opened, then it couldn't be a nail or other fault to the branch circuit wiring, it had to be something upstream of the main. If it wasn't in the aerial conductors where you could examine, maybe inside the mast or something.

Another possibility is that there's a problem with a neighbor, a neutral problem on a neighbor's service, or something with the power company. Checking to see if there was a problem anywhere other than the roof would have been helpful.
I checked the mast to the ground rod below it. 0V . No way for a line problem to get to the roof, I looked hard for that
 

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Discussion Starter · #13 ·
I checked the mast to the ground rod below it. 0V . No way for a line problem to get to the roof, I looked hard for that
Come to think of it, it was a through the roof/eaves service. what we call a roof-jack, meter on the outside wall. So I tried Very hard to make the problem related to that
 

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I checked the mast to the ground rod below it. 0V . No way for a line problem to get to the roof, I looked hard for that
What about maniac roofer putting nail or screw into it? I am not being condescending btw. If it is areal service, and you pulled meter, there is no way there is potential from the house. Did roofers use generator for power or the house for there cords, which btw are probably **** and all rigged?
 

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Discussion Starter · #15 ·
Come to think of it, it was a through the roof/eaves service. what we call a roof-jack, meter on the outside wall. So I tried Very hard to make the problem related to that
One tiny possibility just occured to me, what if the airial nuetral was a poor connection? But Im still not sure that would put voltage on the roof.
 

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Discussion Starter · #16 ·
What about maniac roofer putting nail or screw into it? I am not being condescending btw. If it is areal service, and you pulled meter, there is no way there is potential from the house. Did roofers use generator for power or the house for there cords, which btw are probably **** and all rigged?
My first thought before i went. roofers didnt have gen, they left early about half way through the job and said well be back when it is fixed. I did my checks with no roofers on the job and nobody home
 

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One tiny possibility just occured to me, what if the airial nuetral was a poor connection? But Im still not sure that would put voltage on the roof.
If roof is not in contact with ungrounded conductors, and you are saying the meter is pulled, a loose neutral at the mast is not going to give you 60v potential from roof to earth. Something energized is touching roof.
 

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Discussion Starter · #18 ·
If roof is not in contact with ungrounded conductors, and you are saying the meter is pulled, a loose neutral at the mast is not going to give you 60v potential from roof to earth
i was actually thinking about at the trnsfrmr. However, before i killed power i was measuring with a clampmeter and getting an almost perfect sum of the phase and neutral current readings. Just a few tenths off, but attribute that much at least to the meter placement on the conductors
 

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My first thought is "WHY DID YOU LEAVE IT LIKE THIS". If some one leans a aluminum ladder on the house is wet weather you now have that shock hazard at ground level when someone touch's the ladder.

Think of it theory wise.
You have a ungrounded roof, that is hot how is it getting there?
Nail in wire. -- no you pulled the meter.
Service entrance entrance issue. - you say you checked and it looks good. ( should of called POCO to pull main fuse to confirm).
Backfeed from water or gas pipe. you did not say what the current was on the temp ground wire.
Jumping over air from cell tower - If you found this true you would be rich.

Cowboy
 

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Discussion Starter · #20 ·
My first thought is "WHY DID YOU LEAVE IT LIKE THIS". If some one leans a aluminum ladder on the house is wet weather you now have that shock hazard at ground level when someone touch's the ladder.

Think of it theory wise.
You have a ungrounded roof, that is hot how is it getting there?
Nail in wire. -- no you pulled the meter.
Service entrance entrance issue. - you say you checked and it looks good. ( should of called POCO to pull main fuse to confirm).
Backfeed from water or gas pipe. you did not say what the current was on the temp ground wire.
Jumping over air from cell tower - If you found this true you would be rich.

Cowboy
I didnt want to leave it like that. But I had tried everything i could think of. I dont recall if there was current on the grounding jumper. I am inclined to say there was none, or i wouldnt have left it that way. I do realize the danger and liability/responsibility of that.
 
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