# Finding hidden electrical wire?



## 232323 (Mar 31, 2008)

We are looking at installing a new, mechically fastened membrane over corregated roof panels. Between many of these corregations, conduit was run tight to the bottom of the roof decking. Is there any tool available that would detect these electrical wires from the top of the roof that would help eliminate the possibility of screwing into the conduit. Most of the ceiling below is finished with no attic access.


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## 480sparky (Feb 1, 2009)

If the existing roof is metal, you're gonna find this a tough challenge. I doubt there's much out there that will be able to trace wires through a metal roof and a metal conduit.


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## Tinstaafl (Jan 6, 2008)

Are the existing panels metallic?


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## 232323 (Mar 31, 2008)

Tinstaafl said:


> Are the existing panels metallic?



Yes it's galvanize metal...maybe 20 or 22 gauge. I talked to the local electrician, he thought his underground detector would work. But, he too wasn't sure if it would work through metal???


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## Tinstaafl (Jan 6, 2008)

Not likely, unless it's a very high-end device. Even then, it wouldn't be foolproof.

I agree with 480, tough situation.


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## ohiohomedoctor (Dec 26, 2010)

I would say make access and a diagram which can be transferred above. No matter what you do you need to get a rock solid cya contract from day one.


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## Hardly Working (Apr 7, 2005)

Heavy load on the wires and a Thermo Cam?


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## griz (Nov 26, 2009)

Unless you can send a signal (pulsed?), that you can identify/detect, through existing wires/conduit, don't know how you can do it.


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## hdavis (Feb 14, 2012)

NCV won't work because of the metal. I have a thermal imager, and it wouldn't work either. It's theoretically possible to pick up the magnetic field if there is a load on the circuit, so maybe there is something out there that will work, I just don't know what it is.


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## 480sparky (Feb 1, 2009)

hdavis said:


> ........ It's theoretically possible to pick up the magnetic field if there is a load on the circuit, so maybe there is something out there that will work, I just don't know what it is.


Whatever it is, it ain't gonna be cheap.

I'd say $5k at minimum.


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## GO Remodeling (Apr 5, 2005)

try professionalequipment.com Also, somewhere I read that there was an ultrasonic scanner for wall cavity inspections. Might be the ticket. If you get one, can I play with it?


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## rselectric1 (Sep 20, 2009)

232323 said:


> We are looking at installing a new, mechically fastened membrane over corregated roof panels. Between many of these corregations, conduit was run tight to the bottom of the roof decking. Is there any tool available that would detect these electrical wires from the top of the roof that would help eliminate the possibility of screwing into the conduit. Most of the ceiling below is finished with no attic access.


Good for you for even asking.

Most times, the roofers just shoot them all home and they will eventually hit one just below the surface and play dumb.

SOP is for the roofers to do their thing, and plan on having an electrician trace down the shorts.

Happens all the time with corrugated roofs. I never blame the roofers, and actually appreciate the work.


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## GO Remodeling (Apr 5, 2005)

thermo camera might work if you leave the lights on all night and then scan on a cool morning. the fixtures should telegraph through. It's a matter of connecting the fixture pattern dots (electrical runs) and thinking like an electrician :whistling. Otherwise, cut an access and explain it's cheaper than hitting a bunch of wires and less dangerous for your workers.


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## 480sparky (Feb 1, 2009)

olzo55 said:


> thermo camera might work if you leave the lights on all night and then scan on a cool morning. the fixtures should telegraph through. .........


That's assuming only _lighting _circuits are installed there.


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