I’m doing some repairs and painting a lady’s house.
Today I was priming and backbrushing primer up under this piece of flashing running across the south exterior wall when ZAPPP!
I got a most surprising shock.
My little non-contact tester pen tells me that the entire wall is hot. The tester chirps practically anywhere on the wall–all the way down the wall–inside or out.
The panel is on the corner of this wall, and there’s a small subpanel fed right off it into the adjacent bedroom. The exterior panel is newer, but has no main disconnect, one ground rod I see. The subpanel is old but does have functioning breakers. The subpanel is fed by a 60a breaker in the exterior box.
A 15amp breaker in the subpanel labled “lights” shuts off the problem.
It’s panel siding, T1-111, and there’s cellulose blown in. I see the holes.
What in god’s name do you think is causing this whole wall to be hot?
My best guess is that the cellulose is damp and conducting?
Has anyone seen anything much like this?
Got any suggestions?
I recognize this is a very dangerous situation, I don’t need that lecture… but I’d like to possibly get a handle on it before I bring in the electrician…
Replies
Leakage going through a screw into metal studs or conduit...
PaulB
http://www.makeabettertomorrow.com
http://www.finecontracting.com
Wood T1-111 siding, wood framing.
Damp wood can coduct electricity."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I used to mow lawns when I was in High school. I remember one time pushing the mower under a bush with one hand and pushing the branches up with the other hand. The spark plug lead must have been hitting a branch because it got me at the other end of the branch. I never considered wood as a conductor till then.
Most likely a nail through the metal siding/flashing and into a wire. Which is why metal siding is supposed to be grounded.
The non-contact testers are unreliable, and not a good indication that the whole wall is hot.
wood siding and framing.
So you think that the tester is unreliable even though I can hold it 6" away from the exterior wall, just about anywhere on the wall, and it's going off, flip the breaker and it's quiet?
Do the electricians have a more reliable way of testing--finding where the short is?
P
If the entire flashing along the roof edge is "hot", that will make everything within several feet appear "hot" to the tester.With some of the non-contact testers there are ways for an experienced user to make an educated guess at how strong the field is and therefore how close the short is. But it's an "art" at best.The way I'd shoot it is to try to determine where the offending circuit is routed, and look for potentially offending nails along its path. A circuit tracer type tester might be useful for following the circuit in the wall, if that were available.In this case, if it really is "lighting", likely there is a wire running up though the top plate to a ceiling fixture, and a nail for the flashing went through the wire,
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Nail going through a conductor.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Probably a nail or screw into hot wire like others say, however here is another possibility. A powerful radio station is nearby and the metal is somehow at the right wave length to pick up the RF from the transmitting antenna. No Joke! I have a real confirmed experience about this phenomena. the radiation was strong enough to light a florescent tube nearly a foot away. Oops! I forgot about the light switch curing the problem, guess I better go to sleep.
Virginbuild
Edited 8/13/2009 9:04 pm ET by Virginbuild
But I got ZAPPED.. I didn't hear FM in my head or anything.
;-)
If I was the electrician I would start opening boxes and disconnecting the wires, testing as I go, until I isolated the offending segment of wire. Generally you try to guess which box is in the middle and then cut them in half in each subsequent step depending on which way the fault is.
Some lazy electrician (or bootleg carpenter) couldn't figure out how to get the wiring from point A to point B so just stuffed the romex up under the flashing to hide it. Forgot where the run was and nailed into it.
You got a floodlight somewhere nearby?
Once took an outdoor sconce off a wall to replace some siding. Got zapped when I stuck a flat bar between the siding and sheathing... it was Thermax (the foil covered foam board), and hot, hot, hot<G>http://www.tvwsolar.com
We'll have a kid
Or maybe we'll rent one
He's got to be straight
We don't want a bent one
He'll drink his baby brew
From a big brass cup
Someday he may be president
If things loosen up
One time I was replacing all knob and tube wiring in an old farmhouse
with a walk-in attic area leading to and ending over a garage which had a run of k&t wiring beneath the attic floorboards to the garage lights and rec's.
I never found out what exactly was causing it but the little hand held radioshack gizmo, that had a little red light come on if there is juice in a wire,
would come on when standing in the middle of the attic with the thing at shoulder height.
So there I am standing like I'm calling for an encore performance at a concert with my gizmo instead of a match or bic lighter with no wiring around except what is beneath the floorboards.
I replaced that floorboard wiring with romex and the light never returned.
Do you beleive in ghosts? snorK*
Sounds like a good situation for a tin foil hat. :)
BruceT
My metal roof here reads Hot , I have a circut for a cieling fan tucked up under the insul and it's close to outside skin. Makes it fun when checking other circuts that are run alike.I did do a job salvaging chestnut studs and panel boards in an old shack down in the smokies, and the damm roof would give ya a tingle ( metal) seems the power lines in had sagged and rubbed thru, the owner who OK'd the demo thought it was dead for the last 10 yrs, but it was very alive.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
"If Brains was lard, you couldn't grease much of a pan"Jed Clampitt
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Once again, this is why metal siding and roofing should be grounded.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Generally our copper roofs wind up with copper gutters, either box lined or fascia hung and that downspout is the ground path. Some roofs get lightning protection added by others.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
"If Brains was lard, you couldn't grease much of a pan"Jed Clampitt
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So, how did this turn out?
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I finished my work and put the owner in touch with the electricians I use.
I showed her what circuit the problem was in and suggested she leave the breaker off til she could have it ferreted out.
When I spoke to my electrician he said he'd had one recently where the wire lath corner and cove details in the plaster wall had become hot from a nail into the conductor.