dang box fill chart

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Old 01-25-09, 04:23 PM
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dang box fill chart

hello fellas, brushing up on my code stuff here, this might be a silly question, but i'm working with table 314.16(a) Metal Box sizes. In the first column labeled "box trade size" under that the third column has round/octogonal, square, and device running down it. For the boxes with "device" behind it, is that already taking into consideration there will be a device in it or do i have to plan on the 2 volume allowance for the device yet.

My question specifically is if i have a 3x2x2-1/2 device box, and i want to simply install 2 14/2 romex's, it is really border line and having to add 2 allowances for a device puts it over the limit. Thanks.
 
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Old 01-26-09, 06:21 AM
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Box

2 14/2 Romex cables will fill the box. You will not have room for a device. 4 current carrying conductors and 1 ground is 5 allowances at 2 cubic inches each is 10 cubic inches. You will need 14 cubic inches for 2 14 gauge Romex cables and 1 device.
 
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Old 01-26-09, 08:32 AM
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You apparently have what is often called a "handy" box. These boxes are badly misnamed--they are not handy for anything.
 
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Old 01-26-09, 02:07 PM
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Originally Posted by Wirepuller38 View Post
2 14/2 Romex cables will fill the box. You will not have room for a device. 4 current carrying conductors and 1 ground is 5 allowances at 2 cubic inches each is 10 cubic inches. You will need 14 cubic inches for 2 14 gauge Romex cables and 1 device.
His box is 3x2x2.5 = 15 cu in. So why won't the device fit?
 
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Old 01-26-09, 02:21 PM
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Using the math does not always equate to the volumes listed in the tables. For example a 4" sq. x 1 1/2deep box is listed at 21 cubic inches. The math would come up with 24 cubic inches.

The table lists a maximum of 6 #14 conductors in the box that size.
 
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Old 01-26-09, 03:37 PM
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Originally Posted by ErikCHaugen View Post
His box is 3x2x2.5 = 15 cu in. So why won't the device fit?
Because the box is not really 3x2x2.5, just like a 2x4 stud is not really 2x4.
 
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Old 01-26-09, 06:25 PM
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um, the box i'm dealing with is not a handy box, i am working what i call a raco 355, or metal nailer box. this box is pretty dang close to 3x2x2.5 . the code table lists this box as 12.5 in3 and 6 max conductors. which i need room for 8 conductors really, 4 black and white wires, 1 ground, 1 metal clamp, 2 for the device. Forgot about the strap . so at #14 i have 16 in3.

like i asked earlier, does the code table already account for a device, or does that still need to be figured in? If its already figured, i can drop 2 conductors, to put me at 6 conductors and 12 in3. That might account for the fact the listed in3 doesn't match the calculated in3.

talk about a pain in the butt.
 
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Old 01-26-09, 08:13 PM
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No, the code table does not already account for a device. It does need to be figured in.
 
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Old 01-26-09, 09:28 PM
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Please just do yourself a favor and install a larger box. It will make it easier to get everything into the box.
 
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Old 01-27-09, 12:19 AM
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That will be the easy soluation and My SOP is get the biggest box for that useage like nail on single gang if you can get 21 or 23 { I am not kidding but manged to find few of them if you look right } but the smallest I will be confotbale is 18 cu in boxes.

The 15 and 12'ers I will personally not touch them at all.

The handy box is the worst one to mess around and it is a royal pain in butt with it.

Merci,Marc
 
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Old 01-27-09, 07:02 PM
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upgrading to a larger box is a larger task than what you fellas realize. we use these boxes all the time, like religiously. and for the application i've presented, they work great. And actually today i looked and they're stamped for 15.8 in3, .2 in3 from cutting it...

BUT, Iowa is now implementing a new statewide inspections enforcement of the 2005 NEC. So that means getting people like my boss to learn and accept these changes, like box fill. So, heres what i need to know, for doing just general outlets, what are you guys using for boxes that pass inspections. I can't imagine doing a whole house with 4x4 boxes and mudrings. It has to be metal. I can't sell my boss plastic, and i'm not interested either.

We'll get this figured out yet
 
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Old 01-27-09, 07:31 PM
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Nova,

What is your resistance to plastic boxes? Does your area require metallic raceways like conduit or MC cables?

There are deep metal boxes that are probably 22 ci.

Plastic boxes have been used for years. They are durable, quick to install and do not require grounding like metal boxes. Carlon has a line called SuperBlue that are more rigid than their regular line.

Sorry to hear that your boss is so resistant to change.
 
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Old 01-28-09, 08:04 AM
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Box Fill

".2 in3 from cutting it.." Please explain this part of your statement. Are you cutting the box to reduce the depth? If so, why?
 
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Old 01-28-09, 08:16 AM
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I think "cutting it" means "being big enough", not a literal cut.
 
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Old 01-28-09, 08:27 AM
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Boxes not listed in the code book are required to have the cubic inch listed on the box. As you can see you can not just measure the box and get the cubic inch capacity for the box.
I agree with above, this is a good time to move into the 21st century and use plastic boxes. That is unless you are still using greenfield. Then there is no hope for you!
 
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Old 01-28-09, 12:11 PM
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Clarification

Thanks. John. Now it makes perfect sense. I believe almost all boxes now have the volume stamped inside the box.
 
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Old 01-28-09, 05:14 PM
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done some thinking today, i'm roughing in a house, i'm going to run plastic by my boss, and then that's all the farther i can go. When the inspectors tell us to change every outlet box out, boss can change'm. Changing boxes is only the tip of the iceberg of things that will have to change. He just came to me not to long ago, "uh, from now on no more 10/2 and 6/2 romex, gotta be 10/3 and 6/3" i just kind of bite my lip and think to my self, no kidding, i've been doing it for a over a year .

I personally prefer the metal boxes since i do about half commercial work, conduit and mc cable. I also like the clamping for romex. And metal ceiling boxes for fans. I did hear that with plastic if the box is sticking out the drywall slightly you can take a sander and make it flush?

I thought all metal boxes were stamped for cubic inches, raco doesn't. i only have one kind of box on site now that has a stamp on it.
 
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Old 01-28-09, 05:46 PM
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Sorry to hear that your boss is just catching up on changes that took place years ago in other areas.

Are Code change update classes offered in your area? Mike Holt has a decent book about the changes complete with illustrations that you may want to look into.

Rarely have I had a plastic box too proud of a surface. normally it is the other way around and an extender is needed.
 
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Old 01-29-09, 05:57 PM
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we've had two classes now put on by our distributor that we are required to take as part of continuing education for the state. And there just great, everyone learns something, doesn't matter if you know the code in and out. So i'd say that by the end of the year all the electricians in the state should be up to par. We work in an area of the state where there aren't even so much as city codes to abide by, so you can probably imagine the situation .
 
 

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