Conduit

[Mike]

I have begun looking at how to run one or more central conduits from the attic to the basement for wiring. This would keep everything in wall, and leave me open for more expansion.

I'll be doing some exploratory cutting around one of the walls that is in a central closet that should do nicely and my thought was to put 1" or larger PVC piping (have to review the sizing) through the 2x4's from the attic down to the basement (comes out near my basement stairs and can then be run behind a wall to the wiring enclosure).

My question: Assuming the location turns out to be as good as I think it will, are there any considerations or recommendations anyone can add? I'm guessing someone here has already done this, so if there is wisdom tied to this, I'd greatly appreciate sharing in some of it.

 

[DavidL]

Best if the pipe runs down an interiour wall so that insulation isn't an issue for both routing and heat loss. Of course this depends on what climate you are in.
Put a nylon pull rope in with the wiring bundle to pull new wires later.
don't tangle the wires (or rope) around when feeding it through the pipe.

 

[rocco]

I preferred multiple, smaller conduits to one large one, (if it is feasible). The reasons:
First, the smaller holes are structurally more sound,
Second, the cables are easier to manage and less likely to tangle, and
Third, there is less chance, and better control over crosstalk.

But keep in mind this relationship: The cross-section of a pipe is proportional to the square of it's inside diameter. In other words: it takes four 1" pipes to provide the same cross-section area as one 2" pipe.

 

[Mike]

That is exactly what I was looking for. I was thinking about the smaller holes for the structural reason as well.

It is an interior wall (actually a wall between my office and a closet) and now I just need to do a little cutting to make sure the wall is falling in the right place for this. On the closet side there may be a thicker vertical beam (6 inches high? 2 inches wide I think) from what I can tell, but if it is one piece, then the office side should work. Cutting into the sheetrock from the basement stairs will let me finalize this and see what im dealing with.

Otherwise it's harder and I need to cut into the wall at 'wife friendly zones' based on a balcony and how the basement only covers the back half of the house.

 

[huggy59]

Another consideration would be fire codes. Often you may not run a single conduit from top to bottom thru multiple floors because it gives fire a way to traverse from floor to floor. You may have to have each floor have it's own conduit break and run another one to the next floor, etc. That allows you to put in firebreaks between conduit runs. It might be ok to do it outside, and not inside. Check with an electrician or the fire department for local codes.

 

[Mike]

Ok, part II of this: I'm trying to clean up wiring done by someone else that ran from the attic down to the basement. It went down through the side of the house through a bedroom wall into what is the garage (bedroom is on second floor, does not extend over garage). It then runs to the right to reach the back half of the house (half-basement covering the back half, no basement under the front half).

This was done outside the sheetrock, so is not real pretty. It also wasn't done using any conduit or the like.

I've been considering ripping all the sheetrock in the garage off, reinsulating and fixing this issue (also need to have an electrician in to run more electrical lines upstairs to clean up the circuits (split off circuits by room)).

My problem is the conduit going down from the attic inside the walls makes sense (a series of smaller ones), but when I have to make a right angle turn to go towards the back half of the house, what is the best way to accomodate that?

I was thinking of making a panel that could be taken off to expose the vertical and then horizontal conduits (may need 2 of these). This way any new runs could be run through the conduits in the wall, then manually setup to be snaked to through the other leg. When thats done, the panel covers it up again. WAF is preserved (wife hates current setup, but fortunately garage is old and a mess to begin with).

This area gives me more options than the central spot (assuming I redo the whole room and redo the wiring currently in place). On the bright side, this could give me the motivation to run component video everywhere and all the other goodies I missed originally.

Any suggestions?

 

[Squintz]

Check out the flexible drill bits at home depot that are like 54" long. I picked one of these up and now I feel like a pro when running wires. The holes in my drywal need not be any larger than a single gang box. I know your talking about running conduit and this flex bit may save you some time patching drywall if you have to cut it out.

 

[Micah]

Just a tip with those flexible drill bits. Make sure you're straight in the wall before you start drilling.

I failed to as careful as I should have and ended up putting a hole in my neighbors kitchen wall.

 

[Mike]

I'm not as worried about re-sheetrocking as I don't think the garage has been touched in 30 years or more. They are a mess to begin with, so not only can I reinsulate those walls once I'm done, it will look much better if I do that.

The other walls are unfinished and I figured I would finish them at the same time.

I will have to look at those bits, I am sure they will come in handy.

I had not seen multiple conduits run when a right angle was required (and then thought of the panel piece to allow you to take it out of the horizontal and feed it up vertical or vice versa). The other part was are there other considerations when running it horizontally versus vertically?

 

[bfisher]

One thought about running it horizontally - I would use the smooth rigid conduit (not the flexible conduit). The ridges in the flex conduit would make it hard to push wire through when horizontal (could catch the end of the wire).

I have similar access points on the first floor where conduit is run from the second floor to the basement. Make it easier to work with when I can get access halfway through "it's journey". My access points are just single gang boxes for each conduit. Hardly even notice they are there.

 

[Mike]

I was thinking to use PVC pipe, should I be looking at something else? A few 1" or 1.5" runs should be small enough to not disturb the frame and give me enough capacity to run the wires I need (need to see how many I need).

 

[Steve]

I think you can only use metal indoors by code. Plastics can emit poisonous gas if it burns. That's what I was told when I wanted to use that gray pipe indoors.

 

[bfisher]

that's very possible. My house already had some plastic conduit installed in places, so that's what I used as well. I guess check with your local code to verify...

 

[jlehnert]

A few comments.

I've never had any trouble with using plastic conduit inside. In the case of smurf tubing (the blue flexible stuff), it's designed for in-wall use. However, YMMV. Check with your local inspector.

As huggy points out, some jurisdictions won't allow one continuos run from basement to attic. Again, check with the inspector. Two things you WILL have to do, is to put firestop caulk around the pipe where is goes through the floor, and to firestop the top (or bottom, or both) of the pipe. A good trick for the top is to tie a relatively good size flat washer onto some strong string, drop the washer a few inches into the pipe, and then put in a squirt of expanding foam (ie Great Stuff). Once the great stuff is dry, you can then apply the firestop caulk on top of the foam, and it won't drip all over the inside of the pipe. If you need to add another wire later, just pull the string to pop the entire nine yards out. Of course you don't need this trick if you are using smaller (<1.5") sized pipe.

Per code, you cannot have more than 4 ninety degree curves in one run. In real life, do go over 2, as it's just too diffacult to pull the wire otherwise. Also, decide which way you are going to pull the wires, from the top or from the bottom. Make sure when you assemble the pipe that the male ends are pointing in the direction you are going to be pulling. IOW if you are pulling from the basement, start with a female end. That way you don't take a chance of the wire getting caught at a joint.

 

[Mike]

Thank you. Great information. I'm mulling over how big to let this project get. If I do run the conduit, the question then becomes do I fix what is there now. That will require unhooking everything from the basement, pulling it back up to the attic and rerunning it. Considering that it is quite possible they could get damaged during this, it may just be easier to rerun.

Rerunning and re sheetrocking would be the 'right way to do it' and it would come out great, just a hell of a lot of work.

On the bright side, I would be able to run component video to every room, and replace the CAT5e with CAT6. Would also give me the motivation to run controls for multi-room audio for the upstairs.

Hmmm. I'm leaning towards it, just need to think this through and consider anything else I want to throw up there as well.