Conduit over existing circuit...

[The Shat]

I'm in the process of remodeling an attached garage. The panel for both garage and house (shared) is on the north wall of the garage, and the house is attached to the south wall of the garage. Therefore, all of the wires from the panel go up the wall to the attic, across the joists, and into the attic of the house. There's probably 15-20 different 12-2 Romex wires up there, none of which are in conduit.

Questions:
1) Is there a type of conduit that can be placed over these existing circuits that doesn't involve disconnecting them and pulling them through?

2) Can I bridge the joists with plywood approx. 2' wide and staple to the plywood? I know having wires running from joist to joist without staples is a no-go. Can I build an enclosure for the wires out of lumber (plywood on bottom, 1"x4" on sides, and plywood on top?

3) If I have to do a regular type of conduit, can I just use PVC?

4) How many wires can you run through one conduit by code?

Clearly, I'm not an electrician! I have no problem wiring switches and outlets, but don't know all of the codes.

Thanks in advance.

 

[rockwithjason]

What are you trying to accomplish?

 

[The Shat]

I'm getting ready to put a lid on my garage re-model, but see all of these wires running across joists that aren't secured to anything. Sure, they're stapled every 32" where they hit a joist, but I could reach up and grab on to one if I wanted to, too. I know that's not allowed by code. I figure if it's legal to staple them to a stud, that a 2' wide chunk of plywood nailed to the top of the joists would give me a substrate to adequately staple the wires to, right?

Can I nail a few 8'x2' wide sections of plywood across the top of these joists, and then staple the wires to the plywood? Would that be up to code?

 

[benjamintmiller]

Are there permanent stairs or a ladder leading to the attic, or is there just a scuttle hole?

As I understand it, if there's only a scuttle hole to the attic, then you can lay romex across joists and staple it down just like has been done, except within 6 feet of the hole. Within 6 feet of the hole, the cable must be protected, and I've always seen a 1x laid down (not plywood), and the cables fastened to that.

As to the number of wires allowed in a conduit, that depends on the type of cable, distance, and type of conduit. There are tables in the NEC that will tell you this. In a common scenario (12 gauge THHN), 1/2" EMT would hold 9 wires, and 3/4" EMT would hold 16 wires. You'll find that it becomes very difficult to pull the wires well before you hit those limits, so most 1/2" conduits only have 4-5 wires in them.

As always, codes vary all the way down to the city level. You'll get far better advice from your local inspector than from anyone on the Internet.

 

[The Shat]

Thanks for the reply. There aren't permanent stairs yet, but I do plan on installing pull-down attic steps, so even though it's really a crawl space, I suppose it's viewed as an accessible attic. I plan on nailing 1"x across and stapling to that, or maybe a 2"x on edge so I can keep them nailed to the side of a stud so nothing is inadvertently placed on top of the wires.

 

[rockwithjason]

The plywood idea would work well for what you want to do

 

[sberry]

Leave them alone and find something else to worry about, they can lay joist to joist.

 

[kbs2244]

I tend to agree with sberry.

But if you are planning to put some kind of flooring on top of the joists for occasional storage just be sure you keep any nails away from the romex.
When you put up your ceiling you will be covering everything up
and “out of sight, out of mind.”

 

[rancherbill]

Leave them alone and find something else to worry about, they can lay joist to joist.

I tend to agree with sberry.

I totally agree.

TICK, it's off your list. Now get on with the other things on your garage remodeling list.

If you have more items on the list, post them up and maybe we can knock the off also.

 

[wyliesdiesels]

If put more than 9 NM-b/Romex cables in a raceway or conduit, they will have to be derated, which opens a whole 'nother can 'o worms. Dont bother...staple 'em every 4 1/2" and within 12" of j. boxes and protect them near openings as has already been mentioned and check it off your list!

 

[zmaxmotorsports]

Put some 2x4s in the attic across the rafters,strap the romex to the side to protect it if youre worried about it.