Is it safe to run conduit through foundation under grade?

[crazybrit]

Question on running conduit into a basement.

Currently power and a single phone to my shop are wired along the sill plate of the basement foundation (7' basement ceiling height), then out through the siding and down externally via conduit into the concrete (red arrow in both pictures).

I want to run 2 runs of CAT6 and 1 run of coax from the basement to the shop and for various reasons I don't want to run it along the current (red) path.

Instead I want to run it between the basement and the shop via the path of the blue arrow.

I'm going to hire a contractor to make a 6" wide cut in the concrete between the house and the shop. The $100 they quoted me is about the same as me hiring a saw and buying the blade. My question is whether it's safe to drill a hole in the foundation below grade so the conduit can run in the 6" wide channel and through the foundation into the basement as one straight horizontal run. I'd rather not have to bring the conduit up vertically outside the house and in through the siding as currently done.

After I'm done I'll be filling the 6" excavated area with concrete but I'm just concerned about water entry into the basement. Maybe it's a non issue or there are ways to mitigate?

 

[The Cobbler]

I'd say a reasonably good chance it would leak . any time you penetrate a foundation there's increased risk of leak.

 

[kaymccampbell]

It could leak. You could use lots of caulk. It could still leak. Why not come up to just below the siding and put your hole there? Then you can put your condulet on the wall and enjoy a less potentially leaky installation.

 

[mikedodge]

Stuff is run through foundations below grade all the time. Water pipes in houses and all sorts of stuff in commercial buildings. If it's done right it's not a problem.
If it were my house I'd probably do it in the air or outdoor rated wire on the wall with no conduit and save a lot of work.

 

[4x4Pete]

I would only put a conduit through a wall below grade if it was the only way to do the job. I've witnessed leaks from inside conduits that penetrate walls below grade. The wall to conduit isn't a big deal to seal. It's when the frost heave cracks the plastic conduit and then water leaks in and its almost impossible to seal with any real security. Worse one was main feeder to 6 story retirement building. 4" conduits, water pouring out of the conduit down the main feeders and on to the basement floor. Power was on and scary as hell to look at. Your installation will not be life threatening but a total pain if it leaks. Good luck with the project.

 

[finn]

Water and wastewater pipes are commonly run through concrete basement walls every day with no issued.

 

[Smoker]

I ran a sewer and water line out of the basement through my foundation wall to my last shop. No problems whatsoever, just dig down on the outside so you can seal it really well. I used a carbine core bit and a big Hilti drill, try and get as snug a fit as possible. Zero leaks.

 

[kngelv]

Can you just trench it in grass behind your house and go into the shop on the side? I highly doubt somebody’s gonna cut that slab 6 inches wide for $100. Did you misunderstand the quote? iIt would cost more than $100 just to come out and set up.

James

 

[doctordirt]

After conduit installation, seal around it with hydraulic cement or a roofing tar

 

[larry4406]

As mentioned about sewer pipes in walls, this happens with hung sewers on our new construction homes.

We use a link seal type product between the pipe OD and circular foundation hole. Link to typical product:

Flexicraft PipeSeal Pipe & Conduit Penetration Seals

Flexicraft PipeSeals seal the area between pipes and wall and floor penetrations quickly with and inexpensively with rubber links.

www.flexicraft.com

If you go this route, you need to pick the correct link size and number of links based on the pipe OD and wall hole ID. In your case, core your wall to the size needed.

We also then tar over this penetration on the outside of the foundation. As further insurance, I install a vertical 4” perf pipe tee’d into the foundation perimeter drain and back fill with stone. This perf pipe is capped about the penetration.

 

[Lt CHEG]

As long as you’re below the frost line I don’t see a problem. I use hydraulic cement around concrete penetrations without issue. Use a little tar type waterproofing over that and you’ll get water through the foundation wall someplace else before you’ll get water through that penetration.

 

[wssix99]

I did this below my floor and through my foundation wall, so I wouldn't have the water issue, but I suppose going under your floor would be a non-starter here...

Getting this underground will be great. The one thing you should plan for is that water WILL be inside the conduit at some point, so you will need direct burial wires to go through this run. They are waterpoof and have all sorts of goo inside that you have to clean out when doing the terminations, but you should be rewarded with long life. You'll just need to spend some time to make sure you have the right wire.

 

[engineer2]

Can you drill through above ground and use an LB box, like the one in the picture?
If you use PVC conduit or RMC, it'll be there for future upgrades vs burying a cable.

 

[crazybrit]

Getting this underground will be great. The one thing you should plan for is that water WILL be inside the conduit at some point, so you will need direct burial wires to go through this run.

So originally I got some surplus DB but the OD was quite a bit larger than standard CAT6 and I was concerned it was going to be harder to pull.

Then someone on a local forum posted looking for some DB locally so I traded him the 200ft I had for 200ft of standard CAT6.

It's just 7' between the house and the shop. I was planning on running a single length of conduit without any joints sloped slightly down towards the basement. I was also planning (inside the basement which is finished) to bring the conduit into a junction box mounted on the wall. From there it'll make a short 90 degree vertical turn up to the ceiling. I figured the junction box can serve as a pull opening and if there is any water ingress it will exit into the junction box.

~shrug~ probably made a mistake trading the DB. Was trying to help someone out.

Can you just trench it in grass behind your house and go into the shop on the side? I highly doubt somebody’s gonna cut that slab 6 inches wide for $100. Did you misunderstand the quote? iIt would cost more than $100 just to come out and set up.

Nope. Only concrete between shop and basement. When the contractor was pouring our new sidewalks I had him give me an estimate. Said around $100. Obviously I told him he'd be doing it next time he was local to me rather than a ded trip.

 

[brownbagg]

yes, but we usually sleeve it, with a pipe bigger that the conduit, that give it some slip and also make repair easiler