Bruce,

A little expert guidance from you would be appreciated.

Given a situation where a person installs steel single gang boxes for romex
12 gage wire, with ground, what is a minimum depth for a single gang 2" X 3"
box for a receptacle or switch, one set of wires in, one set of wires out.

Thanks!

Harold

On Fri, 12 May 2006 19:15:23 -0700, "Harold and Susan Vordos"
wrote:

Bruce,

A little expert guidance from you would be appreciated.

Given a situation where a person installs steel single gang boxes for romex
12 gage wire, with ground, what is a minimum depth for a single gang 2" X 3"
box for a receptacle or switch, one set of wires in, one set of wires out.

I'd have to break out the books, but I've never been called on fill
issues unless it's really stuffed inside the box.

The standard "handy box" is somewhere around 14 cubic inches -
that's what the 'small' plastic single-gang boxes are rated at. All
new production boxes and mud rings are stamped with the size, and the
older ones you can look up in the catalogs.

There's a formula for how many cubic inches needed per wire, and so
many CI for the device (receptacle) in the box, and I do not have it
memorized. But if it's one 12-2 Romex in, one 12-2 Romex out, and a
normal duplex receptacle with the wires landed on the screws (no
wire-nuts and pigtails to eat up space) you should have no problems at
all with fill.

Oh, and for a steel single-gang "Handy Box" you can only use the top
bottom or back knockouts if there is a device mounted in the box.
There isn't enough room between a conduit connector coming in a side
KO opening and the device screws otherwise - you can get away with it
with a toggle switch, but there simply isn't enough room for a
receptacle without pinching wires or grounding out a screw terminal.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

The quick rule is as follows:
A number 12 wire is rated at 2.25 cubic inches per 'Unit'
A number 14 wire is rated at 2.00 cubic inches per 'Unit'

Any wire coming in and stopping is one unit
Any through wire (only applies to conduit) is one unit
ALL ground wires count for 1 unit (no matter how many)
EACH switch or recepticle counts as TWO units.

For your switch boxes you have
white wire = 1
black wire =1
ground wire =1
switch =2

Total of 5 units times 2.25 = 11.25 cubic inches MINIMUM

The 2-1/2" deep 2"x3" box at 12.5 cubic inches is the smallest you could
use. If you used 14 ga wire you would get 10 cubic inches and could use
the 2" deep box. Any current production boxes will have the capacity
stamped on the inside.

I had a friend who got called on the wire count at rough in inspection,
had to replace serveal nasty boxes. But I have found that the closer you
get to the max, the harder it is to get things stuffed in the box.

Harold and Susan Vordos wrote:

Bruce,

A little expert guidance from you would be appreciated.

Given a situation where a person installs steel single gang boxes for romex
12 gage wire, with ground, what is a minimum depth for a single gang 2" X 3"
box for a receptacle or switch, one set of wires in, one set of wires out.

Thanks!

Harold

"Bruce L. Bergman" wrote in message
...
On Fri, 12 May 2006 19:15:23 -0700, "Harold and Susan Vordos"
wrote:


But if it's one 12-2 Romex in, one 12-2 Romex out, and a
normal duplex receptacle with the wires landed on the screws (no
wire-nuts and pigtails to eat up space) you should have no problems at
all with fill.

Bruce, I'm just an ameteur, but is it typically wise to wire through a
receptacle ("...wires landed on the screws...")? Seems like it's a hassle
for maintenance down the years. It's just as simple to wire nut a 'pigtail'
and isolate the receptacle.
BTW, I know it's extra labor, how is this done in new tract housing?

Thanks, Ivan Vegvary

Thanks for the replies, guys. Turns out the fill requirements now dictate
that a box of 18 c.i. is required to meet code (for the aforementioned
requirement), at least according to the schedule posted on the Raco site.
http://www.hubbellcatalog.com/raco/R...?FAM=RacoBoxes

What's strange is it's not easy to buy the large boxes required (3 x 2 x
3-1/2). Shelves are jammed with 2-1/2" deep boxes that don't meet code
when wiring with 12-2. Go figure!

Harold

Very little residential wiring is done with 12-2 except for the heavy
duty ciruits in the kitchen.


Harold and Susan Vordos wrote:
Thanks for the replies, guys. Turns out the fill requirements now dictate
that a box of 18 c.i. is required to meet code (for the aforementioned
requirement), at least according to the schedule posted on the Raco site.
http://www.hubbellcatalog.com/raco/R...?FAM=RacoBoxes

What's strange is it's not easy to buy the large boxes required (3 x 2 x
3-1/2). Shelves are jammed with 2-1/2" deep boxes that don't meet code
when wiring with 12-2. Go figure!

Harold

On Mon, 15 May 2006 21:05:50 GMT, RoyJ wrote:
Very little residential wiring is done with 12-2 except for the heavy
duty ciruits in the kitchen.

....or my entire garage and basement. Then again, I built the place
myself. Certainly is harder to work with than 14-2.