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| Subject - Box fill consumed by wiring devices... | |
| Romex Racer |
I've read 314.16(B)(4) and I've never had an inspector mention this. If I have an 18 CI single gang box, it can accomodate 9 #14 wires, does this article mean that if I plan on installing a duplex recepticle the box can only contain 7 #14 wires? Wiring devices count as 2 of the largest conductor in the box? Thanks! ..........Richard |
| lctrc789 | Racer, are you referring to article 370-16(a). If you read article 370-16(b)4 you will find that the device is counted as 2 wires not one. Every device equals 2 wires. 18 CU. in box 14 Ga. wire equals 2.00 CU in. ea. 1 device = 4 CU.in all gr.=2 CU.in total 6 Cu.inches. You now have 12 Cu. innches left 6 wires. with 14 gauge wire. Two sets out one set in. Or 3 pairs of 14/2 romexes max. I try to always use 20 Cu. in boxes. Hope this had helped you some. |
| JimmyDee | quote: Yes, that is what it means. Keeping in mind a couple of things, the code says any device and that would include a switch, GFCI, single receptacle etc. Any other things that count as a wire, have to be deducted also like has already been said, all the grounds, internal clamps, fixture hickeys and studs. I like to oversize the boxes and put only the 3 1/2" ones in where at all possible. More room is better. Jim |
| in2serenity | yes Romex Racer, you are correct. pretty much in an 18 cu" box with a device you can have 3-14/2, 1-14/2 and 1-14/3, 2-12/2, 1-12/2 and 1-12/3 etc. etc. If you would like to have 2-14/2 and a 14/3 you would need a 20cu" box. 3-12/2 in a 20cu" box comes out to 20.25cu" but i never seen an inspector fail it even though its a 1/4 cu" over. |
| JimmyDee | RomexRacer, Check your e-mails for a MS Word doc. I can't share it openly because it has some copy written stuff in it but I think you will like it. Nice web page. Jim |
| Electricman | Romex, I always use 20.3 cu.in. boxes form carlon part #B120A and sometimes B122A which are 22 cu.in. . We do mostly residential work and with all the switching that customers ask for its nice to have that extra room in those boxes. Most of the houses we do have switched recepts all the way around the room so we run 14/3 to every recept box and if you want to feed the circuit in the miidle of the run you need a box that can accomidate 2 14/3s and 1 14/2 add the device and your up to 22 cu.in. . I believe the bigger boxes give you much greater flexibility for your circuity plus they dont cost all that much more. In2, You ought to work in my area we got lots of wire counters roud here 
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| in2serenity | What area might that be? I did alot of residential in PA. It was in the suburbs of Philadelphia and no one even paid much attention to it except me. Things here in TN seem to be the same aswell, I was working for a local contractor and I couldn't believe all the violations he wanted me to do. I quit none the less, not gonna do it right then i'm not going to do it. |
| Electricman | In2, Lancaster, Berks, Bucks, Montgomory,Schukill countys etc.. you name it most of south east Pa. do alot of work for a custom builder I get into some areas that hire inspection firms to do their underwriting, In fact I had one today tell me that 1/2 pancake boxs are not code. After I discussed it with him he kinda saw things my way and let it go. Lately we have been running into alot of inspectors who are really looking at things more closely than they use to, which I welcome, for I am one who likes to do things by the letter. Once a long time ago I got busted for one box in the whole house that was one wire over and since then I have never done it again. How long ago has it been since you have been up here cause it sounds like I wire in your old stomping grounds? |
| in2serenity | I just moved to TN in Sept. of 2004. I wired alot of homes in Bucks, Montgomery and a few in Berks. It was definetly a conflict of intrest that the contractors hired their own inspectors who would often let things go. I myself never used the 3 1/4" pancake boxes only the 4" with 1 14-2. |
| stedder | Isn't ther a 1 count for every splice (wire nut) in the box also? Or am I just goin' overboard? |
| Ryan_J | No, Stedder there is no count for wire nuts. BTW: Change in the 2005 will require a double count for unspliced conductors (looped) longer than 12". |
| Mike Delaney | I agree with Electricman. I go with a 20.5 cu box. I've seen those 18 cu from home depote for .18 ea, I spend about .28 for the 20.5, I think its well worth not having to come back and change out the box because of a failed inspection. I also use Allied plastic 2 gangs w/ 44.5 cu for .77 ea, and 3 gangs w/ 60.0 cu for 1.24. These boxes are awsome for box fill, usually a 2 gang has 32.5, and a 3 gang 45.0 cu. Can't beat it. Plus they make installing dimmers and timmers a snap! |
| kbsparky | The older Codes made you deduct one conductor for a yoke-mounted device. With the proliferation of large devices such as GFCI's and 1000 watt dimmers, they changed it to require two. The problem I have with this requirement is that your standard wall switch or duplex receptacle outlet should not take away 2 of your conductors, when they only take up the space of one. I'd like to see them scrap that rule, and replace it with one that takes into consideration the actual (cubic inch) volume of the device, and apply that to the wire-fill tables. That way, you'd end up having to deduct 2 for a GFCI or dimmer, but it would only cost you one conductor for a single pole wall switch. |
| JimmyDee | quote: I go way back to the 1960s and if my old memory serves me correctly, it was 2 back then for a device as well. Jim |
| CooCooMike | out of curiosity can anyone tell me how or why you can justify ded. for the cable clamp |
| JimmyDee | quote: Because they said so. You do realize it is only for internal clamps. I don't think it was ever intended for some of the new type of plastic internal clamps but the old metal ones in the metal boxes would sometimes cut into the insulation of the wires so, it was probably a good idea. Jim |
| kbsparky | quote: NEC 370-6(a)(1) 1987 edition: ".... an additional deduction of one conductor shall be made for each strap containing one of more devices..." NEC 370-6(a)(1) 1990 edition: "... an additional deduction of two conductors shall be made for each mounting yoke or strap containing one or more devices ..." I stand by my original assertion  -Ken |
| JimmyDee | quote: You, of course, noticed my disqualifier. quote: Jim |
| kbsparky | >>...if my old memory serves me correctly...<< LOL ... yup. That's why I keep my old code books here on the shelf back to the 1965 edition. My "old" memory sometimes has a hiccup or 2 that I need to verify every now and again  -Ken |
| CooCooMike | see jimmy that's what happens when you use that invisible ink
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| Ryan_J | quote: Because it takes up spacce? :) |