Removing defective wiring from conduit

I have an underground metallic conduit that carries the circuit to my pool light. After feeling a slight shock in the water, only when the light is on, I began troubleshooting the light circuit. There are three wires running through the conduit. After disconnecting all three wires on both ends I performed a resistance test between the three wires. I am consistently reading 20K ohms between any of the individual wires. As a further test, I connected a GFCI receptical in place of the switch and connected the light circuit back to the load terminals on the GFCI and it immediately trips when I turn on the breaker. This happens even when the light fixture is disconnected at the pool end. I does not trip with only the GFCI connected to the line and the light circuit disconnected.

Would the above test results indicate that I need to replace the wires in the underground conduit?

If yes, what method could I use to pull out the old wires? They seem to be stuck.

 

Another yikes ,,, give them a yank and see what happens. Any shock near a pool is extremely dangerous as there may be a small shock now but that potential could change at any time and lead to a big shock.

 

Is there some kind of lubricant I can pour down into the conduit, in sufficient quantity, to loosen the wires and which can remain there after I install the new wires?

 

I dont think lube is the answer. The pipe is probably big enough to take more wire should some melted insulation stick,, just yank.

 

I took out a screw-in plug from the top of the junction box so I would have a straight line out of the conduit. I then wrapped all three wires around a 3 foot long pipe. I used a block of wood as a pivot on one side and pulled up on the other end. These wires are not moving at all. I am estimating I had at least a hundred pounds of pulling force and they didn't budge. The conduit is at least 80 feet long and has at least three 90 degree bends.

Any other ideas I could try?

 

I think that it is time to get out the shovel...and not just for the handle to wrap the wires arround. It has been my experience that when wires go bad in a conduit they tend to arc and weld themselves to the wall. Even if you could pull them out (probably breaking at least one in the process) you would leave sharp metal globs on the interior of the pipe which will tear at the new wire's insulation. Secondly, the metalic conduit could be entirely corroded and that could be the cause of the tight wire. I would suggest trenching a new PVC conduit in and pulling new wire. Make sure the wire is moisture resistant! THWN, I think.
Scott E.

 

I pulled so hard that the wires snapped off about a foot into the conduit. The conduit is encased in the concrete surrounding the pool. Digging is out. Looks like I don't have a pool light anymore!

I appreciate all the help regardless.

David

PS I am posting a new question titled, "Installing new 220v line".

 

you could always start at the opposite end from the pool and start digging up the conduit, taking it out joint by joint until you find the bad section of wire. Then you could replace just the removed sections of conduit, leaving the part that is embeded into the concrete alone. That, of course, assumes that the bad section of wire is not in the conduit section that is embedded in the concrete.

 

I am not an electrician but I pull wire in conduit day in and day out for last 30 years. Metalic conduit is a real problem, rust corrosion and electrolysis. I would recommend digging up the conduit at the first place you can reach it outside the pool apron. If you can pull the wire from there to the light fixture, you might be able to use a junction box (surface mount)and replace remainder with pvc to switch. If you can budge the wire, be sure and attach a pull line to the wire when removing so that a line will be in place to pull the new wire back. I have found that any type of EMT (thin metal conduit) or galvanized has a short life around chlorine. As you know chlorine is an oxidizer and will cause rust really quick on most any metal except maybe good stainless steel. I am not sure if you are talking about a light below the water surface or a pole mount near the pool. I suspect you mean a light below the water surface. If its a pole mount, You could place a new light pole outside the apron.
I wish I had better news. For wire pullers, pvc was a great invention. There are a number of pulling lubes that can be purchased at most elec. supply houses and Bigger home improvement stores but they do nothing for stuck wire. For a small pull like yours, common dish washing soap works well. Good commercial products are Yellow 77 or Polywater which I prefer.
If you are fortunate to get to the stage of pulling new wire and have multiple bends (90*) use lube and have a helper push on the wire being fed in. A little pressure on the feed end makes the pull much easier.
Good Luck
Terry

 

I tried that yesterday. Since both ends are in the concrete, I was trying to guess how it is routed. I dug down 12" in the only dirt area that it could have been and could not find it. I think they probably followed the side of the pool and put it all in the concrete. I am starting to wonder if they even used conduit in the concrete. They might have saved a buck or two by just laying the wires into the concrete itself and put conduit on the ends for good looks!

I figured out that since the junction box for the pool light is against a block wall, I can run new conduit on the wall from the box to a position over the dirt, then go underground to the garage. I will relocate the light switch to the junction box near the pool. It will be GFCI protected.

David

 

GFCI is a great idea and I'm not sure low voltage might be safer.
Sometimes tracing buried wire is difficult and short runs are cheaper to reroute. We use electronic locators to trace buried wire in our business. All electric companies have this equipment but generally are only willing to locate for free from the meter to the transformer if your elec. feed is underground. You might call and see if they would locate it for you or many telephone contractors have this equipment and might be in the yellow pages but will charge you for sure. I would try to reroute with modern day materials (pvc). and be done with it. Electricity and water are a really bad combination. Do it right and swim in peace.
Good Luck
Terry