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Old 11-21-2017, 11:26 AM
 
Location: SoCal
346 posts, read 1,082,849 times
Reputation: 402

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Hey all,

I have an issue that's new to me and could use some advice.

I have a front yard post light that went out. I have power up to a junction box in the garage, then it goes dead at the light. It's 1/2" conduit underground to the light post. It's about a 12' run to the light.

I think it's safe to say something corroded underground.

I'm trying to pull new wires through, but the existing wont budge. Any advice appreciated.

Thanks!!

MandK
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Old 11-21-2017, 11:31 AM
 
12,253 posts, read 13,543,953 times
Reputation: 16556
Break out the shovel and start digging.


I'm going to assume the fact it's not moving is due to a pipe collapse or disintegration and filling with dirt preventing the wire from moving, and not a hidden box in the ground somewhere you are overlooking. Even if you pull it out, more than likely it's going to break where it's pinched, and at best case you can use the broken wire to estimate in the ground where the break is assuming you know where the pipe runs. You'll need to repair the breakage before running a new wire anyway.


I'd disconnect the wire at the junction box in the garage and at the light and measure continuity between the 3 wires on each side. Then, I'd get a long wire, splice to one end, and test for continuity of each wire through the pipe to see if you have a breakage on any of the 3 wires.


Based on those results would dictate what I do next (most likely dig).
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Old 11-21-2017, 11:55 AM
 
Location: SoCal
346 posts, read 1,082,849 times
Reputation: 402
Quote:
Originally Posted by BostonMike7 View Post


I'd disconnect the wire at the junction box in the garage and at the light and measure continuity between the 3 wires on each side. Then, I'd get a long wire, splice to one end, and test for continuity of each wire through the pipe to see if you have a breakage on any of the 3 wires.
Thanks Mike! I'm not exactly sure how to measure/test continuity, but I'll google it.
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Old 11-21-2017, 01:26 PM
 
Location: Grosse Ile Michigan
28,921 posts, read 68,878,220 times
Reputation: 35330
Not recommending this, but what i did once long ago was hook the wire to our garden tractor and yank it out. The risk is, if there is a box someplace you will rip the whole thing out of the ground. My current answer would be to abandon the existing and drop a new conduit line. That is what power companies usually do. It is more efficient than digging around trying to find the damage so you can repair a collapsing conduit run. It will eventually collapse elsewhere if that is what the problem is. Rent a trencher drop in a new line and you are done in a few hours at a fairly minimal cost. I would use PVC. if you wanr stenchet put concrete around the PVC. Then backfill the trench. If you are using steel pipe and it is a short run, maybe use PVC coated GRC (too expensive for a long run). You do not want it rusting out again.
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Old 11-22-2017, 12:11 PM
 
19,699 posts, read 59,585,832 times
Reputation: 36586
Quote:
Originally Posted by mandK View Post
Hey all,

I have an issue that's new to me and could use some advice.

I have a front yard post light that went out. I have power up to a junction box in the garage, then it goes dead at the light. It's 1/2" conduit underground to the light post. It's about a 12' run to the light.

I think it's safe to say something corroded underground.

I'm trying to pull new wires through, but the existing wont budge. Any advice appreciated.

ps - I used a small tractor to try to pull a 4/0 in 2" conduit. I nicely skinned off the insulation and made it into scrap.


Thanks!!

MandK
12' is only a couple of lengths at worst. There is a lubricant specially designed for wire pulling that won't damage the insulation. You might try this:
Get some of the lubricant, push some into the conduit, then use an air compressor to blow it through the entire conduit. Work the existing wire back and forth a little to loosen it and get lubricant on it. Use a linesman's knot to attach the new wire so you pull it in place as you remove the old ones. 1/2" conduit is small and you'll just mash things together if you try to push more wire alongside existing ones.
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Old 11-22-2017, 01:50 PM
 
Location: The Triad (NC)
31,375 posts, read 69,765,043 times
Reputation: 37459
Quote:
Originally Posted by mandK View Post
I have a front yard post light that went out.
I'm trying to pull new wires through, but the existing wont budge.
I'd be very surprised if that wire is in conduit.
99:1 it's UF.

With a tugger to help it might be usable as a pull line as you pull in NEW wire (more UF)
but far more likely you'll need to do some trenching too.
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Old 11-22-2017, 02:44 PM
 
Location: Riverside Ca
22,165 posts, read 25,371,892 times
Reputation: 35089
Take a fish tape and shove in from the light side to the house. See how far it goes. Pull the fish out and look at the tip. Do you see dirt on it? Broken conduit.

Now lay it on the ground stretched out going back towards the house where the j box is. Subtract 18 inches as that’s where the conduit should be buried as far as depth. That will tell you where the blockage is.
If there is a tree or shrubs most likely the roots grew around the pipe and basically strangled it or the pipe broke at a junction.
1/2 inch conduit is really crappy. I dont even use it for underground runs. Most likely it’s stuck at the 90s where the conduit stubs up.

I would disconnect the wires at the j box.

Take a shop vac or compressor and see if you can blow air through the conduit to the other side. If you can you just have stuck wires



I would pour some cable pulling lube down both stub downs and pull the cables out one at a time. Grab a good set of lineman’s and pull
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Old 12-07-2017, 09:59 AM
 
Location: SoCal
346 posts, read 1,082,849 times
Reputation: 402
Quote:
Originally Posted by MrRational View Post
I'd be very surprised if that wire is in conduit.
99:1 it's UF.

With a tugger to help it might be usable as a pull line as you pull in NEW wire (more UF)
but far more likely you'll need to do some trenching too.

There was no way on earth to pull new wire. The wire was in metal conduit that was fully rusted through. I should have taken a picture.

Solution: New trench, new wire and conduit. Project now complete.

thanks all for the help!
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