Locating wiring in poured concrete

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Old 11-11-08, 03:44 AM
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Question Locating wiring in poured concrete

Hello, quick question here. My home is constructed of poured concrete w/ rebar. The wiring is run through EMT. Is there an easy way to locate where these runs are at inside the walls? Some of them are easy enough to assume where they are at due to location, but the other ones I've done plenty of electrical projects in the past, but this one simple thing is driving me nuts I'm trying to figure this out just so I can hang some pictures (need to use Tapcon's in the concrete). I think the hammer-drill would make quick work of the EMT if I hit the wrong spot. Thanks in advance.
 
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Old 11-11-08, 04:25 AM
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I doubt you would hit the conduit if you used 1" tapcons, since the conduit should be centrally located in the wall cavity. However, I understand your reluctance to light up things inadvertently. Many electricians will have deep scan type electrical detectors that would help map out the current in the conduit.
Thanks for your service.
 
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Old 11-11-08, 08:23 AM
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I would think the grounded metal conduit would block the detection of electric lines.

But they do make "stud finders" which also detect metal in walls. I don't know if this would work through concrete or not.

Anyway if it did work, I suppose you would want to avoid rebar as well as conduit, so you could drill where no metal was detected.

Hardware and home improvement stores sell stud finders.
 
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Old 11-11-08, 11:59 AM
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I just tried my stud finder as Bill suggested because it does pick up wires when I'm looking for studs. Nothing, the concrete just triggers it to full scale. Thought I might be able to spot some rebar. Maybe another brand. I also tested my Infrared camera to see if I could get any indication, no again.
For just a couple of pictures, I would think a go-slow approach might work, you know, stop and inspect every
1/32"
Good Luck
Bud
 
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Old 11-11-08, 01:35 PM
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most of the time emt is tye-wired to the rebar inside the wall for support. Usually rebar is in the middle of a wall. I highly doubt you will have any problems hanging pictures with plastic anchors.
 
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Old 11-11-08, 01:48 PM
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I agree that the conduit should be deep enough inside the wall so that you won't hit it as long as you don't go crazy with the hammer drill. It should be at least 2" deep or so, but probably closer to the center of the wall.
 
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Old 11-12-08, 11:28 PM
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Thanks for the help, guys. I've been using 1" tapcons for hanging stuff around here. Walls are about 6" thick, so it looks like I'll be ok.
 
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Old 11-13-08, 04:30 AM
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Bill, the detection devices we use don't just detect the solidness with sonar, you actually hook a wire to the device and scan it. The conduit doesn't present a problem, since you are only using one wire in the bundle. But, I think overall the OP will be fine drilling 1" tapcons in the wall, don't you?
 
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Old 11-13-08, 09:19 AM
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I've seen too much construction work which was not done like it should have been done. So I will remain silent on this one!
 
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Old 11-14-08, 02:33 AM
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I think I might take some measurements to see if they did indeed place the conduit in the middle of the wall. There are a few conduit runs on the roof, where I can take some inside and outside measurements to compare the two. BTW, home was built in 1977. Everything (mostly...) appears to have been built according to NEC for that time period.
Service was updated a few years back to 200A w Square D generator interlock panel. At least there's no AL wiring!
 
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