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| Subject - Number of wires spliced | |
| highlt |
I have a code/safety question. I'm wiring lights in my basement for a room we are finishing. I have installed a 15 amp breaker for all the lights with 14-2 wire. The power runs into each switch box. I have four different switches. One switch box is a dual switch box and I have six 14-2 wires entering the switch box which is 36 cu. in. Questions 1. Is there any code violation to tying six wires together with a wire nut? I would be tying six neutrals (white) together. 2. Is 36 cu. in. box big enough to hold all these wires? 3. Also, any code violation to the number of breaks in the power line from the breaker box? My main power lines runs from breaker box to s1 to s2 to s3. So I have three splices in it at each switch box. |
| David Hyatt | 1) not sure 2) No box is to small, you need atleast 42 cubic in box 3) No |
| Ryan_J | 1) depends on the wire nut 2) see David's response 3) see David's response |
| highlt | Does anyone see an issue with tying six wires togehter in a box. Is it uncommon or unsafe to do this many wires in a box. In regards to the box sizing question, what is the actual danger of too small of a box. Is it just overcrowding increases odds of wires coming undone or does it relate to heat, electricity etc. |
| lctrc789 | Guys am I missing something here correct me if I am wrong, As far as the wires in the box and why? well they need to be allowed for free space and for heat that is why the box fill calculations,<<<<<< Question 1, yes or no, depends on what size wire nut you would use, Blue Gray, etc.. Question 2, NO, WHY<> (6) 14-2 romex 14 gauge wires = 24 cu in.. all grounds = 2 cu in.. 2 devices = 4 cu in.. total cu in =30 cu inches even if this box has internal clamps they would count as on all together still being a total of 32 cu inches 36 would suffice.??? Question 3, no this is fine. Is this uncommon to see a box with this many wire nuts or splices not at all. |
| blackrd | You need to subscribe to electrical contractor magazine, it has had an ongoing series of articles on box fill. You probably need to call a qualified electrician. The fact that you are doing this work without knowing what you are doing is extremely scary to me. Good luck |
| Ryan_J | I think David and I were reading it as 4 switches in the box. I know thats how I read it! |
| lctrc789 | OK , had me going for a minute but, He is saying 4 different switches and 1 dual (2 gang) box So if I am reading it right 2 single gang boxes and 1,> 2 gang???? |
| Ryan_J | Thats what I'm thinking??? 
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| Romex Racer | 6 14-2 cables = 12 Wires All ground wires = 1 Wire 2 devices = 4 wires Total wires = 17 Multiply x 2.0 cubic inches TOTAL CUBIC INCHES REQUIRED = 34 See 314.16 |
| Romex Racer | To see how many wires you can jam into a wingnut, see the manufacturer's recomendation: http://www.idealindustries.com/wt/TwistOnWireConnectors.nsf |
| blackrd | I was reading it as two boxes, "I have 4 switches,one box is a dual switch box, etc."My concern is genuine, I didnt intend to be sarcastic. Is each "switchbox" actually boxes for receptacles, except the actual boxes for switches? |
| highlt | LCTRC789 you are correct. I'm stating I have one dual (2 gang) box. My question for box fill is related to this. I thought to calculate box fill you did the following: 1. Count number of wires for box excluding grounds and pig tails and count all grounds as one. . 2. Take that number and add one for each cable clamp and two for each device. 3. for 14-2 wire sum it up and multiply by 2. Based on this I get 12 + 1 + 3 + 4 * 2 = 40 cu in. So I don't match anyone's calcuations? Do they not make a box bigger than 35 cu in. in plastic? I've had enough of looking for a box this big. I think I'll just put each dimmer in a seperate gang box with four 14-2 wires running to it. Based on my formula I would need two single gang boxes that are (8 + 1 + 3 + 2 * 2) 28 cu in or bigger. BLACKRD I pulled the dual gang box upstairs out in my living room to investigate what the electrician did when wiring the house and it has five 14-2 wires coming into it and one 14-3 wire with three switches (one switch has two on one device). The box is 35 cu in. Seems like the state certifed electrician or inspector made a boo boo. That's why I'm asking the questions. |
| kbsparky | quote: If you look at 314.16(B)(2) it states: "...Where one or more internal cable clamps ... are present in the box, a single volume allowace in accordance with table 314.16(B) shall be made ..." You only have to deduct one conductor for cable clamps, regardless of the number of them present in the box. As for the availability of a 36 cubic inch 2-gang box, we use UnionBox #SN-236. Much better than the "blue" ones. They also have a 41 cubic inch 2 gang box available. For more information on these, click here and scroll to the bottom of the page. |
| lctrc789 | Romex, you corrected me I added wrong, you are right 34 cu.in box would still work even if it did have internal clamps he would meet 36 cu. in capacity. |
| highlt | Any issue with having dimmers in the two slots? The dimmers take a bit more space than a normal switch. Thanks for all the feedback. |
| blackrd | Somebody has a new 4" extra deep box on the market I saw in Electreical Contractor mag. There are also 4"11/16 boxes. Use one of these with a 1/2" mud ring to clearance the dimmers. I couldnt find any special consideration for thick receptacles or switches in the NEC. It would fall under workmanship like manner I assume, but I dont know everything and so I come here to learn. Perhaps Ryan could give some info on deeper switches protruding into the jb, and his opinion on it. |
| kbsparky | quote: Yes, you did. The requirement that makes you deduct 2 conductors for each device is just that. Older editions of the Code only required one conductor deduction, but with the proliferation of larger devices such as GFCI's dimmers, timers, etc. they changed that to 2. The end result is that the Code assumes that every device will be a large one, whether or not that is the case. 
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| blackrd | very good |
| Ryan_J | I haven't seen those yet, but it sounds like a great idea, especially for fire alarm devices, where you have no idea how big the unit will be. Reagarding the box fill, you guys are right, there is nothing in the code that addresses the size of the device. The other question that often gets brought up is "what about the length of the conductors"? The 2005 has a change that will require a count of 2 for a conductor that is looped through a pull box with at least twice the minimum splicing length( 6" normally). I think this is a good change, but it still doesn't address having a 12" long conductor. On second thought, I'm glad it doesn't...it might make people want to cut their wires shorter. |
| blackrd | Where as the old code, a through and through conductor(uncut) was a single count, I thought the same and an uncut loop was counted as two, in the new code. What do you mean by addressing a 12" loop? The articles in EC mag( Ill have to find them) have had an ongoing series on box fill (Charles Miller, author). EC subscriptions are free, and there website is linked to alot of others. Ryan, I think it was a RACO box, and they were promoting it as something new(the depth of it, 4 in.sq.). |
| Ryan_J | A looped (uncut) wire is only counted once unless you have enough length to cut it and make a legal splice with at least 6" of free length on each side. |
| highlt | Guys thanks for all your input. Blackrd no hard feelings...thanks for your help too. |