Electrical through concrete foundation

[Cliff_Johns]

Thanks to everyone, this has all been very helpful. This building is only 14' by 20', so no below-frost-line footings are required. It's a floating slab with a thickened edge.

I need to call the building department tomorrow morning and see if PVC is acceptable, then I will get some pieces to make the "sweep" at Home Depot, I guess. Sounds like 2" will work fine for 100AMP. (welcome back Junkman -- I don't think I have a need for 200AMP, and I'm feeding off my house meter and it's only 200 AMP total anyway.)

They do not allow drains here unless the water is pumped out. so I won't be putting in drain pipe. If I add water hookup, it's taxed differently, so I'll just use the hose for now.

Cliff

 

[Cliff_Johns]

Oh, I forgot to say, I will add a couple smaller pipes too, as Junkman sugested, for the various and sundries that I might decide to add later. Phone especially sounds like a good idea.

I had considered just adding the conduit on the outside coming up the side of the concrete and entering the building and about a foot or so. It would be behind a bush anyway. Are there special problems with that? Or do we go through the concrete mostly so it looks tidy.
Cliff

 

[Junkman]

Glad to be of help..... I know you couldn't see it in the picture of my garage, but I thought it out well before doing mine. Now if I could only find the floor.... LOL.... One trick that I didn't mention was to put a few holes on the foundation wall above the floor. If you don't use them, you just cement them in later on. This is accomplished by hanging pieces of PVC pipe on nails on the foundation forms walls. The contractor can help you with this. I would put a few on each wall in the event that you want to run something outside without drilling through the wood. An example of this would be air lines. I filled mine with expanding foam and just dug out the foam when I wanted to use one.... You can never have enough places to get through the concrete. For those times that I don't have a hole where I need it, I have a Milwaukee hammer drill...... a big one at that!!!!!
As for coming up the outside of the building, you can do that also, but my preference is always to keep everything inside where possible. There is nothing wrong with coming up the outside and then drilling a hole in the side wall. When you do the outside PVC, there is a sliding PVC joint that accomodates any movement so the PVC will not be under stress and crack. It is called an "expansion joint" and I believe that it is required by code. If the slab is going to be floating, and the question will be how much movement there will be. In that event, it might be the better method going on the outside, because if the slab moves a lot, and the PVC can't, it will crack. This is a variable that you will have to get guidance from the local building officials. As for the water, you can pull line through at a later date, after the final inspection and certificate of occupancy is issued. This provision for water, I would definitely put under the slab for frost protection. If it is deep enough to be safe from frost and inside the building, you will be relatively safe from movement problems. Besides, if there is a crack in the PVC that the water line runs through, it will not harm anything. The local topography and water table needs to be considered at all times to make the decision as to what is best. If the garage is on the top of a knoll or hill, there wouldn't be much standing water in the ground.... if it is low lands, then all bets are off. For the small amount of money involved, I would put it in the floor anyway and then if you change your mind, all that you have wasted is less than $50 worth of materials. If you put the outside PVC pipes in sand, then it will lessen the problems of frost. Most conduit problems are a result of poor installation techniques, not materials.

 

[bebster]

Good comments by all. Here's a picture of the "sweeps" coming up through my footing. I put in a 2nd on for telephone/communications lines. The sweeps go down below the bottom of the footing and out the bottom. We put some extension pvc pipes on top of the sweeps to get them high enough to avoid being clogged by the pour.

 

[Alan L.]

Here in north Texas, in every house I've seen, electric service comes out of the ground outside the building, up through conduit to a breaker box. This breaker box is then connected through the wall to the service panel inside the building (or garage) where the individual circuit breakers are installed.

I don't know if this is a requirement or if thats just the way builders like to do it.

 

[Junkman]

bebster...... I believe that it is time to change your avatar picture from the JD to the Cocker Spaniel..... that sure is a sweet looking dog..... /forums/images/graemlins/grin.gif

Alan...... the difference between what is being done in this post and a home are different situations. In a home situation, you have a meter that the underground PVC is connected to first and then it goes to the electrical panel in the house. If the meter is located on the pole in a remote location, then there is a disconnect switch just under the meter before the conduit and wire enter the ground and at the opposite side, where it comes out of the ground it goes up the side of the home and in through the wall. I this instance, the power is coming from inside the homes electrical panel and going to a sub panel in the garage. The NEC (National Electrical Code) deals with each type of installation differently depending on the type of building and other factors that are too many to get into in a general discussion such as this....

 

[L3710GV]

I would also wrap a little insulation or slide a piece of pipe wrap on the pipe, it allows room for pipe to expand, which will help cracking in slab that usually will start at a point like that. It also allows you to move the pipe some to corect alignment

1 1/2" conduit would work for the wire size for that distance and amps- it also fits better on a 2x4 wall- 2" pipe thru a 2x4 plate don't leave much wood

 

[Junkman]

Good thought, however I did try the insulation once and it wasn't all that successful. What I did learn is that a 2 1/2" PVC pipe will slip over 2" PVC pipe nicely. If you want a tighter fit, you can use some tape on the inside pipe. You could do this if you wanted some "fudge factor". I wasn't thinking of the pipe coming up inside the wall, but more likely the sub panel would be surface mounted to a piece of plywood. Since this is a garage, there is no need to conceal the wiring and a surface mounted panel is easier to wire and make changes to later on. This is a personal choice, nothing more.

 

[JimR]

Here is what I used for mine. The black pipe is for a future water line if I ever decide to put water out there. The smaller grey pvc pipe has the cable and phone line in it. The larger pvc pipe is the power line and goes all the way up to the breaker panel.

 

[Alan L.]

Thanks for clearing that up Junkman. After posting it, I thought about it and realized the difference. I am planning a well house and I will certainly bring the power into the building underground. Makes no sense to do otherwise especially if its allowed.