Laying a slab over the main electrical

[klieber]

I'm looking to build a shed to free up some room in my garage. I want the shed to be on a slab foundation for various reasons. The problem is the place I really want to put the shed is directly over where part of the main electrical line runs in between the power company's junction box and my house. It's a ~150' run in total and the foundation would cover about 15' of that, right in the middle.

My question: If something happened and the line needed to be replaced, would I have to rip up the slab to allow them access? Or is the line run in conduit, such that they could just pull new line without having to dig down in that exact 15' section?

I'm not worried about hitting the line - first, it's buried 3' in the ground and second, I'd be hand excavating that area anyway. I'm only concerned about the possibility of something happening down the road that will force me to rip up the slab.

And, since I know the knee jerk answer is "just build the shed somewhere else" -- I understand that's one option. What I'm trying to understand here, however, is the relative risk of not moving it. What bad things could reasonably happen that I should be thinking about?

 

[porschedude996TT]

People build over power lines all the time. There is little chance that the physical power cables will fail. I'm guessing that the cables are encased in a conduit so if by the very slim outside chance that the cable or cables need to be replaced, they would be pulled from one end or the other. Not a fun job but it has been done. If you have direct bury cable, no conduit, it is a bit harder to replace. But how often are these changed after putting them one service? Almost never...build and forget about it!


Sent from my iPad using Tapatalk

 

[klieber]

But how often are these changed after putting them one service? Almost never...build and forget about it!

That's my thought as well, but before I actually start digging, I wanted to check with y'all to see if I might be overlooking something.

 

[dave*99]

Is there any reason that if a failure occurred, a new cable could not be routed around the shed?

When the service to my house was replaced (direct bury cable) the power company ran new wire from the pad mount transformer to my meter. They did not follow the path of the old cable. They found it was easier to short cut right across the septic system field into two of the laterals.

 

[klieber]

Is there any reason that if a failure occurred, a new cable could not be routed around the shed?

Good point -- I hadn't considered that. The only other obstacle is a 8" brick wall, which they could easily tunnel under.

That just made me feel a whole lot better about the situation. Thanks!

 

[matt_i]

I would worry more about people doing the dirt & concrete work damaging the cable.

Wherever its marked, its hand dig. Could be an expensive repair if it were damaged. Could be expensive to have it hand dug.

 

[klieber]

I would worry more about people doing the dirt & concrete work damaging the cable.

Wherever its marked, its hand dig. Could be an expensive repair if it were damaged. Could be expensive to have it hand dug.

I worry about those people too. Mainly how my back is going to feel when I'm done with it.

I'm going to be doing the digging myself. I also got the utility company to clearly mark the lines, so I'll be extra careful in that area. I may rent a small excavator for part of it, but I will personally hand dig the area around the cables.

 

[wasfuzz]

In my area it is ok to build over like you wish to do, BUT not encouraged by the power company. Plus if they had a fault under the slab any cost related to the repair /damage they did getting at the fault would be on you. Talk to them and ask about rerouting a section of the line. It is usually direct bury and not hard to move. They come in, dig up to expose, reroute and splice new in. Often times cheaper than fixing your damages later if it would fault out under your slab.

 

[rlitman]

I also got the utility company to clearly mark the lines, so I'll be extra careful in that area.

The markings may be clear, but their accuracy is often less than you may hope for (+/- 2' is good). Make sure the person doing the markout knows exactly where you will be digging, so they focus their efforts in that area, and don't just shoot a line from point A to B and guess the middle.

 

[tfinniii]

The problem will be if and when the EL needs to be replaced as you will be responsible for charges to run new line and that applies to any buried utility lines.

 

[CNGsaves]

Sounds like OP will be doing hand digging himself to locate the power feed so should be able to determine whether it's in conduit the whole length.

Safe thing to do would put 1/2 of PVC pipe cut down middle over power feed in areas it might be damaged (ie half clamshell over top as protection).

Also, could just put an EMPTY conduit near the electrical feed and stubbed out beyond the building that could be used as replacement if the first one failed.

Might be good idea to put another empty conduit under there anyway for such things as sprinkler system, low voltage lighting, etc.

 

[klieber]

Might be good idea to put another empty conduit under there anyway for such things as sprinkler system, low voltage lighting, etc.

Good call -- will plan on doing this.

 

[Kaizen]

several good points. I'd put in spares if you see a pipe. for 20 bucks its peace of mind.
also on the dig safe. take pictures of the marks before you dig as proof. and use them only as a rough estimate. also see if the guy doing it can triangulate the depth.....depends what he is using. because its supposed to be 3 feet but..........
lastly if its in conduit and backfilled properly you'll be fine. however adding that much weight to an improperly installed conduit could crush it.....not break it and probably no power problems but they wouldn't be able to pull it out in the future. remember you could also have cable and telephone conduit there.