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TITAN2390 09-28-2010 08:59 PM

Voltage in Metal Roof and Gutters
 
I recently purchased an older home with a back porch that was converted to an added room many years ago, maybe 20 or 30. The only electricity in that room appears to be pulled from the original back porch light that was on the wall and ran to a light in the center of the room and two corner flood lights. I had a metal roof installed to cover the poor quality and leaking existing roof. I was up on a ladder installing a TV antenna and bumped against the metal roof and thought I felt a shock. I quickly touched the gutter and did get a shock. A voltage meter to the gutter/roof and ladder showed 115 volts. I immediately figured the roof was nailed into a wire to the flood lights. I can open the breaker and the voltage goes to zero. Before pulling up the metal roof or removing the gutter I wanted to see the extent of the voltage so I took a jumper wire to the ladder and touched the gutter quickly expecting to see a spark or pop a breaker similar to a direct short but nothing happened. I can conect a jumper directly between the ladder and roof and the breaker does not pop nor is there any sparks but the voltage goes to zero. Remove the jumper and voltage back to 115. Can someone explain how this happens?? There is obviously a voltage leak but it is much less than a direct 120 volt wire pinched to the roof or gutter. Any advise on how to proceed??

jddavis 09-28-2010 09:12 PM

Depending on the type of ladder and how good your grounding system is, is most likely the reason the breaker did not trip.

Yes, you do have a short somewhere, if you know which circuit it is on, start by finding all devices on that circuit, then one by one, one device at a time, switch, light, or receptacle. Undo the hot legs then check to see when the voltage goes to zero.


When the voltage stays you are behind the problem wire and it will lie between that device and the one before or after. Most likely you will have to physically trace every wire in that circuit and check for damage.

The reason voltage went to zero when you "jumpered" the ladder was there was zero potential between the two, you effectively made the ladder hot, if you got off the ladder and grounded yourself you would have been shocked again.

TITAN2390 10-04-2010 06:17 AM

Found It.

Fixed It.

Thanks!

a7ecorsair 10-04-2010 07:55 AM

Quote:

Originally Posted by TITAN2390 (Post 511079)
Found It.

Fixed It.

Thanks!

It's great to know you found the problem but since you posted it here, you should at least tell us the fix:yes:

TITAN2390 10-07-2010 07:44 PM

Pulled the gutter down and the 14-2 wire that ran to the flood light on one corner was pushed up behind it. A gutter screw was shot thru the wire contacting the Hot wire. The ground wire was not conected. Due to this and the fact the gutter touched the metal roof and flashing around the overhang it was all energized.


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