DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Electrical (
-   -   Conduit through basement wall. (

bdalekid 01-29-2007 09:44 PM

Conduit through basement wall.
I have to dig a trench for underground cable to feed a sub. panel in my basement. I am planning on trenching 24" deep and stopping at the side of the house. I need to drill a 1.5" hole through the basement wall at the same depth as the trench. I plan on putting a 3' pvc conduit sleeve through the wall to protect the wire , with a LB on the inside of the basement. What can I seal the hole around the conduit with so no water leaks in the basement ? Also what can I seal the conduit where the wire enters with so no water leaks into the conduit and runs down into my sub panel. Or any other suggestions I should try. thanks

whybminor 01-30-2007 02:28 AM

Friend and I had to deal with similar problem. Sealed around conduit with silicone caulk but no idea if that really worked because I doubt any water ever accumulates outside the foundation stemwall at the height of the conduit. More importantly, we located the hole below and to the side of the panel, then angled the conduit up and into the side of the panel. Last, I drilled a small weep hole in the bottom of the L conduit body so any water that came down inside the conduit would be visible and maybe even drain out. None has. Passed inspection just fine though I don't think inspector ever noticed the weep hole.



jproffer 01-30-2007 02:39 AM

First, check local code to see if 24" is deep enough for UM-B. Second, especially if you're not doing full length conduit, you should trench in the conduit (or sleeve) and sweep up at the house to above ground and through the wall with an LB. This will eliminate both water issues.

Third, if you ever are running full conduit, I wouldn't drill any "weep holes" in it. It will cause more harm than good, and it's not necessary if you run back up the walls on both ends before going inside.

jwhite 01-30-2007 05:11 AM

I am with jproffer,
do not enter the home below grade. It will leak eventually.

whybminor 01-30-2007 11:16 AM

Ah, I agree. If there's a way to sweep up and not enter below grade, definitely do that. Problem is that sometimes there isn't.

Proffer -- As for weep hole, I don't think you understood what we did. It's a small hole in the bottom of the conduit body inside the basement, not in the conduit and certainly not outside. Since the hole is at precisely the lowest place in the whole conduit run (from meter post to house panel), all we have to do is occasionally look at the fitting to see if there's any water getting into the conduit.

Buried PVC conduit is notorious for leaking, especially long runs with lots of joints. That's why it's classified as wet location and requires water resistant insulation (e.g. THWN). I think it's a good idea to have an easy way to tell if there's water getting into it. Do you see any downside to doing this?


Phil S.

jwhite 01-30-2007 06:34 PM


Originally Posted by whybminor (Post 31754)
As for weep hole, I don't think you understood what we did. It's a small hole in the bottom of the conduit body inside the basement, not in the conduit and certainly not outside.

Conduit bodies are required to be listed.

Can you offer a link to a company that has had thier conduit bodies listed to be installed with field drilled weep holes?

jproffer 01-30-2007 06:51 PM

While I did, in fact, think you meant outside and underground, to release water, facts pointed out by jwhite remain the same. Also, I dare say you passed inspection because the inspector didn't see it. If he had:no: .

Realistically, the conduit is going to fill with water eventually anyway, if not by leaking fittings, then by condensation.

jwhite 01-30-2007 08:07 PM

I have, on industial jobs, had installations inspected and approved where we entered the boxes from the side using T bodys instead of Ls. We added a length of conduit to the bottom of the T to allow water to drain.

I know of few home owners who want nasty conduit water draining into thier basement.

I also hate the argument that "it passed when I did it" 99.9 percent of the time that just means that the inspector did not see what you did that was mucked up.

Even if the inspector did see it, and pass it, two morons does not make a professional installation.

Electrical conduits are not designed to keep out water. That is why they do not.

Enter the house above grade, and let gravity keep the water out for you.

jproffer 01-30-2007 08:20 PM


Even if the inspector did see it, and pass it, two morons does not make a professional installation.
:laughing: :laughing: :laughing: :laughing:

Nice...I'm gonna have to use that ASAP.

whybminor 01-31-2007 11:37 AM

Don'y quite see the need to be nasty. I asked if there was a problem because I want to learn. And I apologize for the "passed inspection" comment. It was indeed irrelevant. Also, I can see now that my initial post was not helpful. Live and learn.

However.....In this case, entering baove grade wouldn't have helped because the house is on a slope and grade at the meter base is at least 6 ft above grade at the house. So water would have drained down through the conduit no matter what. (Right into the panel of course unless somehting were done to offset it and provide drainage.) The conduit run into the house was already in place when i got involved. The tee was indeed an option and discussed but a small hole seemed simpler at the time. If it's against code then we screwed up. End of story. I gather though nobody here sees a safety problem?

But i'm going to have to do some reading. In general anything that isn't prohibited in NEC is assumed to be ok (taking into account things like "neat and workmanlike" or whatever the exact phrase is). Fittings etc. are "listed" for specific purposes and I realize there are all sorts of places in nEC that say "only yada LISTED for yada" can be used (e.g. two wires under a pressure terminal, backfed breakers). But is there somehting relevant in NEC about field modifying boxes or conduit bodies or enclosures? What's the general rule here?

I really do need to know. The situations I get involved with in Oregon aren't (generally) a problem because it's all standard residential wood-frame construction. But in PR, I've got concrete houses with DC P-V and wind systems to deal with. And NEC code and handbook and Soares and whatever often don't provide full guidance. Plus a lot of the equipment/fittings etc needed isn't available so one has to improvise.

Apppreciate any help I can get.


jwhite 01-31-2007 04:55 PM

If you installed a nema 3 box at the house, with the ug conduit entering the bottom, and the conduit or cable connector leaving out the back, any water that came up out of the pvc would seep out the botttom of the box. You would need a plastic box, or you would need to find a way to ground it.

jproffer 01-31-2007 05:08 PM

Not nasty, I know I wasn't calling YOU a moron and I don't think jwhite was either. More of a general observation.

bdalekid 01-31-2007 07:43 PM

So what do you think I should use to drill a hole through my brick wall then ? I will just sweep up above grade and go through the wall.
Thanks for all the input.

jproffer 01-31-2007 08:35 PM

Get a hammer drill or "demo drill"....same thing. The size of drill you would need is quite expensive, unless you just want a new toy:thumbsup: ...I'd rent it.

All times are GMT -5. The time now is 02:11 PM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1