PING------Bruce Bergman

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

Reply to
Harold and Susan Vordos
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Harold

How deep is the cover?

Reply to
Bob AZ

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.

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Reply to
Bruce L. Bergman

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 > Bruce,

Reply to
RoyJ

But if it's one 12-2 Romex in, one 12-2 Romex out, and a

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

Reply to
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.

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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

Reply to
Harold and Susan Vordos

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

Harold and Susan Vordos wrote:

Reply to
RoyJ

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

Reply to
Dave Hinz

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