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Discussion Starter · #1 ·
I know it's Tuesday, but it seemed like a Monday today. Dead battery in the shop truck, cargo trailer lights didn't work when hooked up to the truck for a job today(trailers are great, trailer wiring is the devil), our shop forklift idler pulley siezed up so our forklift was down, etc.

In any case, the real problem:

Our on call guy got called out on Saturday to a small rural school to check a blown 150A fuse for a feeder to some pool equipment. He determined one phase was bad, continuity to ground. We need to replace the wire.

He rounded up some fuses and wire and went out there today to repull the feeder, by hand with a helper. The existing feeder looks like 2/0 CU x 4 cloth covered wire in 3" rigid, underground. About 150-200' from MDP to pool area, if it runs in a straight line. Should be a pretty easy pull.

Him and his helper can't get it to budge by hand.

The old 1952 and 1961 blueprints are looked at to determine if there are any possible pull boxes, vaults, etc, that may not be known about, and nothing is shown on the prints or with a visible inspection following the assumed conduit path. No noticeable newer patches of concrete either where someone may have made repairs underground.

I go out there with our 10k tugger to see if we can make something happen. Using good heavy rope, I attempt to half hitch on one wire, just to see if I can get one to move, and end up pulling a good chunk of the insulation off the wire before the half hitches grab, gradually applying more force results in pulling the 2/0 in half. I've never pulled a wire in half before, at this size, that's a first. Usually they just break free. Decide to half hitch around all four wires to get a better bite on it. At this point, I'm pulling so hard, the back end of the tugger is coming off the ground, and I'm afraid I'm going to break the tugger or it's gear box. Time to stop and change plans. I need the tugger for another job in a few days so I don't want to break it. I had 10 wraps on the capstan and the tugger pretty much maxxed out, also another first for me.

We put a vacuum on the conduit and get suction at the other end in the pool area, so we know we are on the right conduit and it's somewhat intact, although it could still be broke/shifted underground and pinching the wires.

Bad thing is, we think it may be in rigid all the way, it's hard to know if it changes to pvc, and it probably passes under the gym that's between the MDP and the pool area. So most likely under concrete the whole way.

Tomorrow we are going out there with our good locator that gives depth readings to see if we can follow the path through the school. We will probably shove a fish tape in from both ends once we know the path and see if we can find the bad spot. I really hope it's not under the gym floor. At any other spot, we can probably hot saw, jackhammer and dig down to it, to make repairs.

Just for grins, we also megged the wiring. Everything tested every different which way between hots and ground, yields 0.0M at 1000vdc. Surprised only one fuse was blown.

At the back of our minds is re-running new conduit overhead and around the gym, but it'll be expensive with the path we'll need to take, so we aren't quite ready to give up on the underground conduit yet.

I'm open to ideas or things to try if anyone thinks of something? Also thought of running a sewer inspection camera down the conduit, but I'd have to ask a plumber if the camera head would fit in a 3" with 4 x 2/0's still in it.

Thanks for the help.
 

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Electrical contractor 37 years. Electrical inspector 2 years
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Can you directional bore a new line? Continuity to ground, could it have spot welded when it shorted out?
 

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Maybe find a pull point overhead and use a chain hoist to pull to the max and leave it in tension overnight. Possibly put an air compressor on the other end and blow air to dislodge whatever has it held. If it’s that hard of a fault, it may be welded to the conduit wall.
 

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The wire snapped above ground or did you get a piece out?

Normally i will pull the bad wire in the hope it snaps at the bad point as that give a lot of clues like the type of conduit and distance to fault.
Tracer is the next step as that will give you a clue on the path, possible place that it has been repaired in the past or a structure that has been placed over the pipe. If the area is not to busy directional boring between hand holes may be the cheaper option.
 

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I know it's Tuesday, but it seemed like a Monday today. Dead battery in the shop truck, cargo trailer lights didn't work when hooked up to the truck for a job today(trailers are great, trailer wiring is the devil), our shop forklift idler pulley siezed up so our forklift was down, etc.

In any case, the real problem:

Our on call guy got called out on Saturday to a small rural school to check a blown 150A fuse for a feeder to some pool equipment. He determined one phase was bad, continuity to ground. We need to replace the wire.

He rounded up some fuses and wire and went out there today to repull the feeder, by hand with a helper. The existing feeder looks like 2/0 CU x 4 cloth covered wire in 3" rigid, underground. About 150-200' from MDP to pool area, if it runs in a straight line. Should be a pretty easy pull.

Him and his helper can't get it to budge by hand.

The old 1952 and 1961 blueprints are looked at to determine if there are any possible pull boxes, vaults, etc, that may not be known about, and nothing is shown on the prints or with a visible inspection following the assumed conduit path. No noticeable newer patches of concrete either where someone may have made repairs underground.

I go out there with our 10k tugger to see if we can make something happen. Using good heavy rope, I attempt to half hitch on one wire, just to see if I can get one to move, and end up pulling a good chunk of the insulation off the wire before the half hitches grab, gradually applying more force results in pulling the 2/0 in half. I've never pulled a wire in half before, at this size, that's a first. Usually they just break free. Decide to half hitch around all four wires to get a better bite on it. At this point, I'm pulling so hard, the back end of the tugger is coming off the ground, and I'm afraid I'm going to break the tugger or it's gear box. Time to stop and change plans. I need the tugger for another job in a few days so I don't want to break it. I had 10 wraps on the capstan and the tugger pretty much maxxed out, also another first for me.

We put a vacuum on the conduit and get suction at the other end in the pool area, so we know we are on the right conduit and it's somewhat intact, although it could still be broke/shifted underground and pinching the wires.

Bad thing is, we think it may be in rigid all the way, it's hard to know if it changes to pvc, and it probably passes under the gym that's between the MDP and the pool area. So most likely under concrete the whole way.

Tomorrow we are going out there with our good locator that gives depth readings to see if we can follow the path through the school. We will probably shove a fish tape in from both ends once we know the path and see if we can find the bad spot. I really hope it's not under the gym floor. At any other spot, we can probably hot saw, jackhammer and dig down to it, to make repairs.

Just for grins, we also megged the wiring. Everything tested every different which way between hots and ground, yields 0.0M at 1000vdc. Surprised only one fuse was blown.

At the back of our minds is re-running new conduit overhead and around the gym, but it'll be expensive with the path we'll need to take, so we aren't quite ready to give up on the underground conduit yet.

I'm open to ideas or things to try if anyone thinks of something? Also thought of running a sewer inspection camera down the conduit, but I'd have to ask a plumber if the camera head would fit in a 3" with 4 x 2/0's still in it.

Thanks for the help.
check the fuse on your megger. Sounds like you might have blew it they are easy to blow if you do something wrong
 

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Discussion Starter · #6 ·
Can you directional bore a new line? Continuity to ground, could it have spot welded when it shorted out?
It's under a school, with lots of underground water piping, etc, so I'd say boring is most likely out, although it has crossed my mind. It's not completely ruled out yet, however. We also had the same thought that it may have welded to the conduit, if it is in fact rigid the whole way. Didn't think they'd weld so hard that I couldn't break them free though....

Maybe find a pull point overhead and use a chain hoist to pull to the max and leave it in tension overnight. Possibly put an air compressor on the other end and blow air to dislodge whatever has it held. If it’s that hard of a fault, it may be welded to the conduit wall.
No good place for a chain hoist, we did look at it from that angle, I'd have to build a frame or something. Your other thought about leaving tension on overnight, that's an idea, I could leave the tugger on it overnight, assuming we could lock the boiler/electrical room doors since the panel cover would have to be left off.

The wire snapped above ground or did you get a piece out?

Normally i will pull the bad wire in the hope it snaps at the bad point as that give a lot of clues like the type of conduit and distance to fault.
Tracer is the next step as that will give you a clue on the path, possible place that it has been repaired in the past or a structure that has been placed over the pipe. If the area is not to busy directional boring between hand holes may be the cheaper option.
Wire snapped above ground, right at the half hitches. Still enough left to grab onto for more pulling if I need to.

check the fuse on your megger. Sounds like you might have blew it they are easy to blow if you do something wrong
Megger fuse is OK. Gives good test reading when in open air, only shows poor reading when hooked to this bad feeder, as it should. In more than 10+ years of operating a Fluke 1507 megger, I've never blown a fuse that I can recall.
 

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Some one on the forum (can not remember what subject it was posted under) posted about a old school trick where you add wax lube then lots of bottle of coke or something like that if the wires are simply stuck by rust. Wait 24hrs then pull it out.
It sounded like a good idea as the acid would break up the rust and its not flammable.
 

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If you have the time, try Polywater Cablefree. Had a stuck underground that refused to budge…. Poured about a gallon down the pipe then connected an air compressor to force it down the conduit. Left it over the weekend and it broke loose with half the force I was using before.
I think it’s more than a lubricant…. Breaks down the old pull lube.
 

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If you have the time, try Polywater Cablefree. Had a stuck underground that refused to budge…. Poured about a gallon down the pipe then connected an air compressor to force it down the conduit. Left it over the weekend and it broke loose with half the force I was using before.
I think it’s more than a lubricant…. Breaks down the old pull lube.
 

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It's under a school, with lots of underground water piping, etc, so I'd say boring is most likely out, although it has crossed my mind. It's not completely ruled out yet, however. We also had the same thought that it may have welded to the conduit, if it is in fact rigid the whole way. Didn't think they'd weld so hard that I couldn't break them free though....



No good place for a chain hoist, we did look at it from that angle, I'd have to build a frame or something. Your other thought about leaving tension on overnight, that's an idea, I could leave the tugger on it overnight, assuming we could lock the boiler/electrical room doors since the panel cover would have to be left off.



Wire snapped above ground, right at the half hitches. Still enough left to grab onto for more pulling if I need to.



Megger fuse is OK. Gives good test reading when in open air, only shows poor reading when hooked to this bad feeder, as it should. In more than 10+ years of operating a Fluke 1507 megger, I've never blown a fuse that I can recall.
I have a 1587 and it has 4 different inputs you can plug your leads into easy to mess up sometimes
 

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Any way you can pull on it from the other end or maybe you already tried that. Hook the power back up and give it hell, maybe it will blow in 2 and come free..... ( I'm joking, maybe)
 

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I hate to say ti but if it's rigid in the ground all these years, the only thing left of the pipe is a bit of rust.

If it can be dug up anywhere, that'd be the first thing I'd do, if nothing else, just to see if the pipe is intact or not.

I'd use 1'2" nylon tubing with compressed air, shove it as far down the pipe as you can get it (likely not very far) and see if you can feel it at the other end. If not, most likely the pipe has collapsed.

If air does go through then most likely the wire has sort of glued to the pipe in about 10,000 spots and can't be pulled out.

I've never tried it but I wonder if a thumper would jar it loose.
 

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You're average see snake probably won't like 3" with the wire still in there, they make a micro one with like a .5" or .625" head but it's only like a 80 or 100 foot cable too.

We've watered the aqua gel lube down and poured as much of that as we can down pipes, sometimes gallons before and let it sit.
 

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Many moons ago we used the carbonated soda (Coke, Pepsi or what ever you favorite might be) and wire lube trick.
Use one 2 liter per 50 foot of conduit.
Pour the first 2 liter in, then add some wire lube, force the mix down the conduit with compressed air, repeat.
The soda will foam like crazy so pour slow.

Do not use so much air pressure that you blow the mix out the other end, which should be covered in case you do.
The idea is to leave the mix down in the conduit.

We left the "mixture" set for a few days before putting a little air pressure on the conduit to push some of the mixture out.
Observing what comes out will give an indication of what is in the conduit.
If you get a lot of mud you may have a big problem.
 

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Some one on the forum (can not remember what subject it was posted under) posted about a old school trick where you add wax lube then lots of bottle of coke or something like that if the wires are simply stuck by rust. Wait 24hrs then pull it out.
It sounded like a good idea as the acid would break up the rust and its not flammable.
I would try the polywater product, polywater products have done very well for me. This one sounds something like citrusolve. I bet it leaves the conduit in better condition than soda and no carbonation to deal with. Although they say you need a quart for every 50' of 1" pipe, that comes to I think 9 gallons for 200' of 3" pipe :eek:

My first guess reading your story was it's yellow wax lube cementing the wires in place. On cloth insulation and rusty pipe walls, that would be just about impossible to break free once it hardened.

I bet if you let whatever solution you use get real warm sitting in the truck on a hot day, it will work way better softening up that wax.
 

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You might also try using lots of water. Hot water if possible. The coke trick and polywater seem feasible as well but I have had luck with just plain water. Basically your flooding the conduit with lots of water and it might free up the cable and if there is any debris such as sand or pebbles in the run then it might help move it. I also think that vibration would be helpful as well but I'm not sure how you could accomplish that if the run is under concrete.
 

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Some one on the forum (can not remember what subject it was posted under) posted about a old school trick where you add wax lube then lots of bottle of coke or something like that if the wires are simply stuck by rust. Wait 24hrs then pull it out.
It sounded like a good idea as the acid would break up the rust and its not flammable.
I had good luck with white distilled vinegar, but like Splatz said about the polywater product, you are gonna need a crapload.

Here is a thread that may give you hope, check out post #11. Dissolving Chico X
 

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The problem with this kind of problem is if you spend 2 days trying to free the wires and then give up, who's eating the time? Customer says you should have just started on the replacement.
 
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