On the advice of several - including the local inspector - I'll probably run
the new circuits in my garage in EMT conduit. (And, I'll probably add a
Three quick questions:
1) Do you usually just run 'romex' thru the conduit? Seems like that's the
easiest thing to do.
2) Could all three (or four) circuits - two new 220, one or two new 110 runs
be placed in ONE large diameter conduit, or do you have to limit it to one
run per conduit?
3) How does one size conduit given the answer to #2? What diameter do I use?
4) Subpanels - *must* they be installed inbetween studs? Or can they too be
mounted *on* drywall? Recall that I'm trying to not rip up the drywall in a
Normally, no ... although it can be done to protect the wiring in hazardous
environments under many local codes, it can not generally be used as a
"method of wiring".
Also be aware that you may be required to reduce the ampacity of the circuit
due to heating values in some locales.
That said, I did it on many of the straight vertical runs in my shop because
I had plenty of it on hand and it was passed under the "protection"
You will find that separate insulated wires are the easies to handle in
Your local code will have limits as to the number of wires of a given size
may be run in a conduit of a given size. There are tables for this in the
NEC, and your local inspector will be able to tell you.
See above ...
There will be local requirements as to where a subpanel can be installed,
required clearance, height, etc. Without question, I would anchor it to a
Except for the generalizations above, and as this may change from area to
area, your local inspector is really the best source for answers to your
... and by all means, permit the job and get it inspected. You'll be glad
All great advice. I have worked quite a bit with my local inspector though,
and I have never had the impression that he would be willing to give me that
much of an education in wiring. Unfortunately, the local electrical supply
house won't either (they protect the electricians, and probably their own
butts by not providing a lot of technical info to DIYers with a pair of
brand new Kleins). Both assume you know what you are doing.
There are several good books on the subject - one of my favorites is by Rex
Cauldwell and published by Taunton Press "Wiring a House". Also, the Code
Check series can be helpful. The best piece of advice I can give, having
pulled miles of wire, is use one size larger conduit than you think you'll
ever need. It's a lot easier to get another strand or two through an "empty"
conduit than it is through one that is close to capacity.
Jim Ray, President
McFeely's Square Drive Screws
During a good part of the year I deal with building inspectors almost daily,
and you're right. However, you'll never know unless you ask.
I've run across some real butts, but many of them can be nice/informative if
you catch them in person, and with a respectful attitude ... particularly if
your local municipality is small and allows homeowners to permit their own
work ... and your taxes pay their salary.
When fishing conduit, a two hole rubber stopper with one hole filled
with a glass tube and the other connected to the blowgun on your air
compressor will sometimes get to where the fish tape won't. Put a
little piece of rag on a light string (kite string or fish line?), put
this in the conduit, put the stopper in the end of the conduit and hit
the compressed air. Has saved my butt a number of times. Folks have
done this in reverse using a vacuum cleaner but I've found the
compressed air more effective. FWIW.
Romex doesn't pull easily. Particularly if you try to run more than one
in the same conduit.
It's also more expensive than single-strands.
Multiple runs per conduit *are* allowed.
There are long, convoluted rules about how big the conduit must be. vs. what
is run through it. basically it's a function of the 'cross-sectional area'
of the conduit, and a limit on how full you can pack it. At least six strands
of 10 ga. is 'legal' in 1/2" EMT.
Note: I do *NOT* recommend 6 strands of #10 in a single 1/2" conduit -- it is
harder-n-hell to pull past bends; direct personal experience speaking.
Two 110(120) V runs in a single 1/2" conduit is 'no problem'.
Two 220(240) V runs in a single 1/2" conduit might be a little awkward.
depending on number of bends, and whether or not you pull a 'neutral' wire
(*recommended* for future flexibility, although -not- needed if it is
powering strictly 240V devices.)
I'd probably go with 3/4" for a dual 240 run.
Surface mount _is_ allowed. It's the 'standard' way, when installed in an
_unfinished_ basement, for example. <grin>
6 #10 in 1/2" emt is only allowed if you use very high temp wire, not common
stuff. "normal" THHN is limited to 5 and THHW is only 3 in 1/2" emt
Also if you run more than 3 conductors in a conduit you have to derate the
ampacity of the wire 4-6 wires it's 20% de-rate ( 80% of original ) 7-9 70%
and 10-20 50% !!! Good thing is that they allreddy derate say 12 gauge THHN
for "normal" use it's limited to 20 amps even though it's really rated to 30
amps and you get to use the 30 amps to caculate your derate for the above
The poster should get a copy of Ugly's electrical references ( can get one
at lowes, and I think maby HD too) about $9.00 and WELL worth the cost.
If your going to run EMT conduit to a box it will allmost have to surface
mounted. I guess you could hack the hell out of the studs and feed it but
Maybe I didn't grasp all the fine details but usually the cover of a
subpanel covers the hole in the drywall. You're not going to be able to
mount the panel without any marks on the drywall. If you've got to
patch later anyway if you take it all out... In for an inch, in for a
mile. I'd use a stud finder or whatever to find studs, cut a hole in
the drywall the size of the box. YMMV.
patrick conroy wrote:
if u r installing a sub panel wouldnt you run a hot/neutral/ground of
correct size to the sub panel and then run each seperate circuit from
there. it sounds like he is going to run all the circuits off the main
panel to the sub panel, and then to where he wants them to go.
patrick conroy wrote:
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