I am in the early planning stages of what will eventually be a 2 circuit wiring job (using NM 12-2) for my new attached garage. But, as you might have guessed, I've got a few questions (actually a few more than a few) that one of you folks might be able to help me with.
First, I'll fill you in on the background a bit. My ranch house used to have a two car garage built into the basement. I didn't like that arrangement, so I had a new two car garage built on that end of the house (where the old "garage" was). The new garage is fastened to the exterior brick wall of the house and opens into the basement (which will be finished...in time). The garage roof is built using trusses as you'll see in the photos (I'd like to use some of the empty space up there for light storage....holiday stuff, small boxes, etc.) The garage interior will eventually be drywalled and finished as well.
Anyway, I am now ready to feed electric into the new garage. My current intention is to run two circuits - one for the outside outlets / lights, and one for the interior outlets / lights.
That being the case, I've been reading up on wiring - both on the web/usenet and in several reference books - and I think I'm now ready tackle this project. Prior to submitting the permit application, however, I'd like to pick some brains on a number of concerns I've encountered while planning out the project. I posted some photos of the garage to help explain what I'd like to do. Web address is below. So, in no particular order, here I go....
1. What is the appropriate distance above or below an outlet box (and if it applies, a switch as well) to drill the hole through the stud? One reference calls for 6-8" above or below the box, while the other calls for 12" above. Does above or below really matter? What drives the hole location? The distance at which you staple the NM to the stud? If it makes a difference (though I don't really see why it would), I do plan on slapping nail plates on the studs.
2. When encountering a window (or door), is it best practice to go below the window (or above the door) through the cripple studs, or run the romex through the attic space? Going through the cripples would save romex and the need to protect the cable running through the attic, but if there is a compelling reason to go up and over, I will plan it that way.
Also, if you go through the cripples, is there a distance away from the door/window you have to be? None of my references mention that, though they do mention the alternatives I state above. Of course, one of the books states that it is also acceptable to run the cable through the shimmed space around the door, although I don't think I'd want to do that, especially if later owners decide to take the door out and end up cutting through the cable.
3. Speaking of running romex in the attic space, I will have to for the sake of the outlets in the ceiling powering the garage door openers, as well as the three carriage lights on the front of the garage (go from one light up into the attic space over the garage doors then down to the next). In both cases, the wire will have to run perpendicular to the truss bottom chords (again, see pictures for clarification). Can 3/4" EMT be used as an adequate protection for the cable for the short runs (15' or so) in the attic? My reference books talk about making a track out of 2x4s and 2x6s that would sit on top of the chords, but that's a bit of a pain, and at current lumber prices, a fair bit more expensive, not to mention heavier, and they seem to offer only minimal protection from above. If EMT is allowable per the NEC, do I have to run the individual wires in it, or can I run the romex as is? I have seen EMT run vertically on walls with the romex inside it as is. I know this is a heat issue (and hence can result in derating of the romex), and I'm curious if the requirements change according to the length of the run within the EMT. Also, whether using the track or the EMT, what sort of protection do I need to provide for the few inches of exposed wire at the ends before the cable is fed back down into the garage wall?
4. On the side of the garage attached to the house, I was planning on using 2x2 strips attached to the concrete / brick to support the drywall. For electrical cable run along that wall, my intention was to use 3/4" EMT and just have rather large notches in the 2x2s (which I don't like either, but since I can fasten the boards directly to the old exterior wall, it would likely be OK). However, I just started wondering whether notching the 2x2s on the back side (against the existing house) and running the romex flush against the concrete/brick wall would be sufficient (i.e. much smaller notches since the EMT would be out of the picture). The wire would be at least as far away from the drywall as any other wall in the garage, and there is little worry about hitting it from the other side (unless someone decides to bore through the 8" of concrete foundation). Thoughts?
In the end, if I have to go with 2x4s for a "standard" stud wall, I guess I will.
5. Although I can likely work around this, another question pertains to drilling up through the bottom chord of the two end trusses to get the wire up into the attic space. I don't expect a structural concern since they are both fully supported by other means, but I thought I'd ask.
6. Now, regarding running the two romex cables into the basement (and to the service panel), I will have to go through either concrete or brick, though I haven't measured yet which one it'll be (probably brick). In either case, I'll have a hole going through anywhere from 4 to 8" of masonry. Can I feed both runs through a single hole, or should I drill two? Not a big deal, just extra effort.
7. Last question....for now anyway....has anyone ever experienced interference running electrical along side the control wires for the garage door (particularly, these are the ones that lead to the safety beams near the bottom of the garage door).
Sorry for the rather lengthy post, but these are the questions that make be go hmmmmm....
Pics of the garage are located at: http://picasaweb.google.com/kevindressel /
If you would like to see additional pics, I can certainly accommodate.
Thank you all a lot on this!
P.S. If you respond to me directly, take the _ out of the return email address, but I will be checking this newsgroup regularly.