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BT5150 06-25-2012 06:45 PM

Underground power run to detached garage has failed-what to do now?
 
I just took possession of my new house, which was a foreclosure so there weren't any home inspections, condition reports, etc. I now see that the power connection to the detached garage isn't working, the garage has no power. I did some troubleshooting and it looks to be that the underground cable run from the house to the garage has failed somehow. Unfortunately, the entire run (about 20 feet) is buried under a cement patio, except right by the house and garage where there is a little dirt, covered by mulch. I dug up the area where the cable exits the house and goes directly into the ground and where it comes back up and goes into the garage. There is conduit going into the ground, but the conduit ends about a foot underground so it is just the buried cable running under the patio. Using one of those testers that don't actually need to make contact to show if a wire is live, I get a hot reading from the cable where it exits the house, but I don't get a hot reading where it comes back up by the garage.

Obviously, the cable has somehow failed somewhere under the patio. I guess I would have thought that if the wire had deteriorated enough so that it won't carry current that it would short out and trip the circuit breaker, but the breaker doesn't trip.

Since I definitely do not want to break up the cement patio to repair or replace the cable, I am wondering what other options (if any) I have to run a new cable run to the garage. Unfortunately, due to the layout of the driveway and patio, the easiest option for re-routing the cable is a much longer run. I would have to make a new run in the basement all the way to the other end of the house, punch through the block wall for a new way out of the house, then dig a trench about 70 feet long all the way around the patio to the garage, a lot of work!

I am wondering if there are any easy options for running a new cable under the cement patio in the same area, something which I know nothing about but would be willing to attempt if there is a way to do it. I don't think there would be a way to tie on to the end of the current run and pull a new cable through, because there must be a break somewhere under there. I am just wondering about how they are able to run cables under pavement. My brother owns a restaurant and a few years ago a telecom firm contacted him because they were running new fiber optic cables in the area and needed to run them under his parking lot. (which they actually paid him for!) Its a good sized parking lot and they didn't have to dig up a thing, they just showed up with some special tunneling equipment that burrowed into the ground on one end of the lot and then ran the cables right under the lot, coming up on the other side of the lot, about 300 feet away!

Anyone know if there is a solution for me for this, other than digging the long trench all of the way around the patio? I don't know if anyone makes any smaller-scale equipment like the telecom company used to run cable under pavement and if anyone rents that equipment. Or, does anyone have any other novel ideas for me to consider?

Missouri Bound 06-25-2012 07:17 PM

The tunnelling you mention needs an area open on each side of the directional bore entrance and exit. It doesn' sound like you have that. You can rent a saw and make a saw cut across the driveway, trench out the earth and install your electric line there, conduit would be advisable, and if you want you can run phone or cable for television in the trench as well, in a seperate conduit. You certainly can go around if you want.

k_buz 06-25-2012 07:54 PM

You might try to investigate a different route. It may be more digging, but less work than cutting up some concrete.

curiousB 06-26-2012 09:28 AM

There is the irrigation installers trick of using rigid PVC connected to a garden hose and pushing that through the ground. The combination of forcing it back and forth and the water flow bores a hole. You can do 20' but not much more. Also you need clearance for the pipe for when you just start as it will stick out fully in the beginning. It doesn't sound like you have that clearance given side of home and garage.

Commercial directional boring is not viable for such a short run due to excavation and it would be more expensive than cutting out and trenching the concrete. (rig and crew costs). As can be seen horizontal boring is heavy construction. http://www.ftthcouncil.org/sites/ftt.../NewTrends.pdf

Bottom line, you are either renting a concrete saw and digging a 20' trench or renting a trencher and digging a much longer trench.

AllanJ 06-26-2012 11:58 AM

If you were able to use water spewing from the end of a PVC wand to bore a horizontal hole, how do you back fill it so there is no danger of the driveway above cracking and caving into the hole which now becomes a trench?

Would you consider hanging the wires overhead?

curiousB 06-26-2012 12:03 PM

Quote:

Originally Posted by AllanJ (Post 951982)
If you were able to use water spewing from the end of a PVC wand to bore a horizontal hole, how do you back fill it so there is no danger of the driveway above cracking and caving into the hole which now becomes a trench?

You don't. If you use a 1" piece of PVC the hole might be 1-2" in diameter. Hardly a major loss of earth. If it were 6" conduit well this simply wouldn't work. Its done all the time by irrigation guys.

bubbler 06-26-2012 03:07 PM

Quote:

Originally Posted by curiousB (Post 951987)
Its done all the time by irrigation guys.

Who are long gone when the cracks start showing up :whistling2:

hammerlane 06-26-2012 06:16 PM

Quote:

Originally Posted by BT5150 (Post 951549)

the easiest option for re-routing the cable is a much longer run. I would have to make a new run in the basement all the way to the other end of the house, punch through the block wall for a new way out of the house, then dig a trench about 70 feet long all the way around the patio to the garage, a lot of work!

Sounds like an oxy-moron. Cant have it both ways. Cant be easiest option and be a lot of work.

Seems like you know your options:
1. cut 20' ofconcrete patio
2. dig 70' trench around patio

Let is know the verdict.

rrolleston 06-26-2012 08:15 PM

I was on one job where we used a hydraulic jack a large metal plate and some really heavy pipe with a point on it and kept adding and welding more pipe and we used the hydraulic jack to get the pipe under some concrete. I think it was about 15 feet using the metal plate so the jack had a stable surface to press against.


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