In article , Bill wrote:
Doug Miller wrote:

3/4" is overkill for most NM cabling. 1/2" is ample for one or two 14-2 or
one
14-3; 5/8" quite sufficient for one or two 12-2 or one 12-3. Why bother
drilling smaller holes, you may ask? It's faster. And it doesn't drain the
battery in your cordless drill as quickly.

I like the idea of putting two 12-2 cables through one 5/8" hole. It
goes without saying that safety is my highest priority.

This isn't a safety issue at all, actually. Just a convenience issue.

What is an ideal hole size for a single 10-2 cable? 3/4"? Similar
distance between adjacent holes?

3/4" will accomodate one or two 10-2 cables. I normally space holes about 2"
apart, but there's no hard-and-fast rule about that. Just make sure you space
them apart horizontally, not vertically. Holes through joists should be as
close to the center of the joist as you can get them (holes near either the
top or bottom edge weaken the joist considerably). Same rule applies to
rafters and studs, too.


It is good that no feet will be able to stretch the wire, but I think it
should be protected so that no one can push a box against it as well.

Correct.

I have seen the idea of building a "U-shaped" running board proposed.

Not necessary. Why make more work for yourself?

Hmmm...attaching it low (close to the eaves) seems to offer the running
board the safest reasonable location. BTW, it will be approximately 12
feet long. Surely I don't wish to clutter the area directly over the
existing main and the new adjacent subpanel more than it already is.
Presently wires "spew" from the top plate over the main panel . So, I
will strive that my new work will not impede access. What is a good way
to add protection against the above-mentioned box that someone might be
inclined to push against the running board? A gun? : )

Don't worry about it. A cable stapled to a running board isn't going to be
damaged at all by having a cardboard box shoved against it.

6 cables across an 6"-8" wide board?

No problem. A 1x6 should be fine.

I don't think you've considered the difficulty of attaching
the boards with half a dozen cables hanging off of them....

You are correct (but I can imagine worse, I think)!

3) Why bother with the plastic-backed staples? Code permits plain metal
staples such as these
http://www.amazon.com/NM-Cable-Stapl.../dp/B002CM2IPY
which are much cheaper, and *far* easier to install.

Hmm. I've noticed those in my present configuration. Intuitively, plain
metal staples seem to increase the risk of accidentally damaging the
cabling.

Well, yes, that's true, but only if you're not paying close attention to how
hard you're driving the staples in. :-) Stop hammering when the staple
contacts the cable sheath, and you'll be fine.

Someone suggested that they used insulated staples with nm
cable. I will seek to better understand these options. I don't mind
spending a few dollars on staples if it makes installing cable more
idiot-proof, in case I have a helper! : )

From my perspective, ease of installation is the main reason for using metal
staples, not cost. The plastic ones are a PITA to put in.

We discussed outlet locations (in proximity to panels) earlier.
My main panel is 24" to the right of the back door of the garage. Is
there any problem with installing a duplex outlet in between the panel
and the back door, at 50" high?

None at all.

My concern was that the location was
where someone might expect to find a light switch (so I would use a
coverplate, or equivalent protection).

Not sure what you mean here. Of course you'd use a cover plate -- all
receptacles are required by Code to have cover plates. What do you mean by
"equivalent protection"?

Does the NEC prohibit what I
have suggested?

No.