Another box calculation question
- Thread starter syakoban
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Re: Another box calculation question
One more clarification please...
I know that cable clamps inside a box are counted and that bushings are not. What about Nonmetallic Sheathed Cable Connectors? I know they are primarily outside the box but they do project a threaded section and nut inside.
Thanks!
One more clarification please...
I know that cable clamps inside a box are counted and that bushings are not. What about Nonmetallic Sheathed Cable Connectors? I know they are primarily outside the box but they do project a threaded section and nut inside.
Thanks!
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Another box calculation question
Might you call it a metallic NM cable clamp?
I'd consider it a clamp. Rather viselike.
Might you call it a metallic NM cable clamp?
I'd consider it a clamp. Rather viselike.
jwelectric
Senior Member
- Location
- North Carolina
Re: Another box calculation question
Syakoban
Is the metal NM cable clamp inside the or outside the box? I think that the "clamp" is the part that has the two screws, the rest don't count. The little plastic pop in connectors don't count either. Be careful using a metal NM connector on a nonmetallic box, make sure it is aproved for the use.
314.16 (B)(2) No allowance shall be required for a cable connector with its clamping mechanism outside the box.
[ December 31, 2004, 12:31 AM: Message edited by: jwelectric ]
Syakoban
Is the metal NM cable clamp inside the or outside the box? I think that the "clamp" is the part that has the two screws, the rest don't count. The little plastic pop in connectors don't count either. Be careful using a metal NM connector on a nonmetallic box, make sure it is aproved for the use.
314.16 (B)(2) No allowance shall be required for a cable connector with its clamping mechanism outside the box.
[ December 31, 2004, 12:31 AM: Message edited by: jwelectric ]
1793
Senior Member
- Location
- Louisville, Kentucky
- Occupation
- Inspector
Re: Another box calculation question
Talking about box fill and how the device is counted, how do you count a GFCI receptacle?
Norb
Talking about box fill and how the device is counted, how do you count a GFCI receptacle?
Norb
electricmanscott
Senior Member
- Location
- Boston, MA
- Occupation
- Massachusetts Master Electrician, one man show.
Re: Another box calculation question
The same as any other device.
physis
Senior Member
Re: Another box calculation question
It counts as two of the largest conductor connected to it.
That one always cracks me up. You go to all the trouble of sorting out how to get that exact number that you can only get by using the special formula and everything's gotta be just so then you go "hey, is it alright if I cram this big ^$$ thing in there instead of the regular one?" It just ruins the whole tricky, precision, complicated part for me.
I think most guys just use a bigger box for GFI's. You don't really want to put a GFI with 12 gauge wires in a handy box.
Only bigger.
It counts as two of the largest conductor connected to it.
That one always cracks me up. You go to all the trouble of sorting out how to get that exact number that you can only get by using the special formula and everything's gotta be just so then you go "hey, is it alright if I cram this big ^$$ thing in there instead of the regular one?" It just ruins the whole tricky, precision, complicated part for me.
I think most guys just use a bigger box for GFI's. You don't really want to put a GFI with 12 gauge wires in a handy box.
peter d
Senior Member
- Location
- New England
Re: Another box calculation question
The simple solution is to use deep boxes for everything. You almost never have a box fill problem that way. Shallow boxes certainly come in handy but they are for specialized uses IMO, like a furred out basement wall or back to back situations.
Sam,
I know what you mean. Quite a few hacks...errr, I mean electrical contractors in my area seem to think that the 18 cubic inch box is the only one made, and that you can put as many cables into it as you like. :roll:
The simple solution is to use deep boxes for everything. You almost never have a box fill problem that way. Shallow boxes certainly come in handy but they are for specialized uses IMO, like a furred out basement wall or back to back situations.
Sam,
I know what you mean. Quite a few hacks...errr, I mean electrical contractors in my area seem to think that the 18 cubic inch box is the only one made, and that you can put as many cables into it as you like. :roll:
physis
Senior Member
Re: Another box calculation question
I think you missed it Peter, The handy box and GFI meets the fill requirements but you might not be able to put it together. Literally. I think you have to put the connector on the long side and if you have one of them new boxes with the indent for the ground screw, with 12 AWG under it the GFI crashes into the screw.
It's the NEC that's says a GFI and a foot of 14 gauge are the same volume.
Syakoban,
I'm guessing you're using the NEC to learn this. I'm lucky to understand the NEC after I know it. What you need is something illustrated. The last couple of questions I was just looking at the answers in the pictures. If you'd like you can PM me your e-mail address and I'll send these two or three pages on box fill complete with all the code references and explanaitions in English.
[ January 01, 2005, 02:26 AM: Message edited by: physis ]
I think you missed it Peter, The handy box and GFI meets the fill requirements but you might not be able to put it together. Literally. I think you have to put the connector on the long side and if you have one of them new boxes with the indent for the ground screw, with 12 AWG under it the GFI crashes into the screw.
It's the NEC that's says a GFI and a foot of 14 gauge are the same volume.
Syakoban,
I'm guessing you're using the NEC to learn this. I'm lucky to understand the NEC after I know it. What you need is something illustrated. The last couple of questions I was just looking at the answers in the pictures. If you'd like you can PM me your e-mail address and I'll send these two or three pages on box fill complete with all the code references and explanaitions in English.
[ January 01, 2005, 02:26 AM: Message edited by: physis ]
peter d
Senior Member
- Location
- New England
Re: Another box calculation question
I wonder if the box fill allowance should be increased for large devices like GFCIs and dimmers? Hmmm....perhaps a code change proposal?
Sam, OK I understand what you are saying. I never use handy boxes because of what you mentioned. In fact, the only place a handy box belongs is in the garabge.
I wonder if the box fill allowance should be increased for large devices like GFCIs and dimmers? Hmmm....perhaps a code change proposal?
- Location
- Massachusetts
Re: Another box calculation question
Originally posted by peter d:
In fact, the only place a handy box belongs is in the garbage.
[ January 01, 2005, 09:13 AM: Message edited by: iwire ]
peter d
Senior Member
- Location
- New England
Re: Another box calculation question
Bob, excellent points. I have always considered the box-fill calculations to be bare minimums myself, among other things in the code. Sure, the minimum size will work but to make my life easier I always go a size or two up.
The code tells me that I can use an an 18 cubic inch nail-on box and put 2 12/2 NM cables in it, with a GFCI.
Training and experience tell me that I'd much rather have a deep 22.5 cubic inch box, or better yet, a deep 4" sq with a plaster ring.
Bob, excellent points.
I have always considered the box-fill calculations to be bare minimums myself, among other things in the code. Sure, the minimum size will work but to make my life easier I always go a size or two up.The code tells me that I can use an an 18 cubic inch nail-on box and put 2 12/2 NM cables in it, with a GFCI.
Training and experience tell me that I'd much rather have a deep 22.5 cubic inch box, or better yet, a deep 4" sq with a plaster ring.
physis
Senior Member
Re: Another box calculation question
I don't have a problem knowing what kind or size box to use with or without the NEC. I don't even mind that the NEC didn't do so great a job with box fill and GFI's.
My point is only that after you count your box up the way you have to, if you're using a GFI, counting the box fill was a waste of time because you probably couldn't fit everything the box is allowed to hold anyway.
I only brought it up in case someone finds a handy box in the garbage and tries to use it for a GFI.
I don't have a problem knowing what kind or size box to use with or without the NEC. I don't even mind that the NEC didn't do so great a job with box fill and GFI's.
My point is only that after you count your box up the way you have to, if you're using a GFI, counting the box fill was a waste of time because you probably couldn't fit everything the box is allowed to hold anyway.
I only brought it up in case someone finds a handy box in the garbage and tries to use it for a GFI.
- Location
- Massachusetts
Re: Another box calculation question
Sam I guess I am just missing your point.
Why should we care if the unexperienced listen to the guy at the big store that says a handy box is fine.
A flush mount 50 amp 4 wire range receptacle will fit in a 4" square deep with 6 AWG experience tells me a 4 11/16" deep works better.
Sam I guess I am just missing your point.
Why should we care if the unexperienced listen to the guy at the big store that says a handy box is fine.
A flush mount 50 amp 4 wire range receptacle will fit in a 4" square deep with 6 AWG experience tells me a 4 11/16" deep works better.
peter d
Senior Member
- Location
- New England
Re: Another box calculation question
I do think additional volume allowances should be required for GFCI's, or add an exception to the box fill rules requiring a box X inches deep minimum for a GFCI.
Putting GFCI's in diecast or PVC weatherproof boxes is a really fun job. :roll:
[ January 01, 2005, 12:33 PM: Message edited by: peter d ]
LOL.
I do think additional volume allowances should be required for GFCI's, or add an exception to the box fill rules requiring a box X inches deep minimum for a GFCI.
Putting GFCI's in diecast or PVC weatherproof boxes is a really fun job. :roll:
[ January 01, 2005, 12:33 PM: Message edited by: peter d ]
- Location
- Massachusetts
Re: Another box calculation question
Originally posted by peter d:
Putting GFCI's in diecast or PVC weatherproof boxes is a really fun job.
We generally put a GFCI receptacle and a duplex in the same box for job temp. power.
It will fit in a standard 4" square, I use 4 11/16" deep boxes instead.
peter d
Senior Member
- Location
- New England
Re: Another box calculation question
I usually do.
- Location
- Massachusetts
Re: Another box calculation question
Originally posted by peter d:
I usually do.
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