The actual run may be a little more difficult to determine, but if your are trying to find-out where it ends-up, or maybe any intermediate junction boxes, here are two suggestions:
1. Use a small air
horn (party
horn) and place the
horn bell as close to the
conduit entry as possible, maybe even use some putty to seal the joint, then when the building is quiet: toot the
horn in short bursts while you have other helpers listen for the sound. It may take awhile, but you can usually find it.
2. Use a
smoke generator and make a nozzle
adapter so you can pump it into the
conduit. Look around for where the
smoke comes out. If you can color the
smoke, that helps, too, as white
smoke is difficult to see. Also, adding an aroma to the
smoke can help, too. An old electrician's trick is to blow cigar
smoke into a
conduit. You can't see it, but you sure can smell it.
3. DON'T use water or other liquids.
Conduit comes in abut 10' sticks, so liquids just seep out of the joints. If this is above a sheet-rock ceiling, well . . . . you get a mess.
To double-check you have the right
conduit, count the number and type of cables entering each endpoint. If they are close, but maybe missing a few wires, then there is probably another intermediate
junction box you have not yet found.
Metal detectors can sometimes be helpful, but they don't work for
PVC conduit in a floor slab.
On a more serious note - court cases have upheld that contractors can be held liable for producing inaccurate as-built documents. One case I know about was where a worker cut into a wall that showed on the as-built plans to be 'empty' and instead, cut through a
power conduit which killed the worker. If you are cutting into conduits,
kill the building power if you don't know what's in them!
From a VERY personal experience, don't go poking a metal fish tape down an empty
conduit to see where it goes. I ran one into a hot electrical panel and killed the
power to the whole building. Fortunately for me, the 400 Amp service grounded to the
conduit and blew the
circuit breaker before I was fried. I was left stuck in a dark crawl space waiting for someone to get the
power back on so I could extricate myself. They showed me the melted fish tape in the
breaker box and I just about fainted.
USE NON-METALLIC FISH TAPES!
!!
