Locating conduit in walls by radar

Blitz,

Is the conduit expected to be in the middle (4" depth) of an 8" thick wall, or at 8" depth in a 16" thick wall?

Depending upon the diameter of the conduit, you are looking for, it might be difficult to differentiate it from the rebar that (should be) in the wall...

Have you tried a Metal Detector??? Certainly more affordable than radar.

The wall is 8" thick but if you have had some experience looking through thicker walls, that should help.

I'm not sure about using radar, but I have seen thermal imaging used to good effect to locate cables in walls and in concrete floors. Heating cables buried in a concrete floors stand out like neon signs when viewed with a thermal imager. For best results I suggest running some heavy current either through any cable in the conduit, or even better through the conduit itself (assuming that it is metal conduit that is), before looking for the thermal signature.

Thermal imaging was the first thing that came to my mind...

If the wall is steel-reinforced, using radar or a metal detector will be problematic. Thermal imaging might work. However, if you are using specialized equipment anyway, I would suggest an underground locating system such as utility companies use. Although it's similar to radar, it does not use reflection. The transmitter and receiver are separate devices. Attach the transmitter to an accessible section of conduit, and it turns the conduit into an antenna, generating a high frequency signal. The directional receiver then locates the conduit easily. If the conduit is non-metallic, you can use a clamp-on attachment and turn the wires themselves into the antenna.

I have used the Aqua-Tronics A7 to find conduit 5 feet underground, below an asphalt roadway with concrete base. It should certainly work for an 8" wall. You may even be able to rent one from a local test equipment shop. The first time I saw one, the sales representative came out and used it to find our problem conduit as a demonstration to convince us to buy it (which we did!).

Maybe an ultrasonic scanner would be the solution.

I thought we are talking about ultrasonic radar here?

Try a cable sniffer. I used one all the time when I used to some IT work.

Just hook the cricket to one end of the wire and start scanning the wall. You trace any wire anywere.

Just my two cents....(cause that is all its probly worth)

bill12780

The comments show me where I wasn't clear. There is no access to most of the conduits in the walls or at least we don't know where the ends are. So we can't put a signal on the conduit or wire. For those we do have access to, the conduits contain signal cable that we can't interfere with but which would not pose a hazard if cut. The conduits of most interest are those carrying power circuits and we don't know where those are. The conduits may be either metal or PVC and range from 3/4" to 3". Most of this conduit has been in place for 10-20 years or longer.

Based on this we have decided to use radiography (gamma ray, x ray, other names) since it can detect the voids caused by PVC, which radar might miss, and will distinguish rebar from conduit better than radar.