View Full Version : Electrical box clamp connector question


Dave Carney
06-11-2006, 01:08 PM
Does a clamp connector fill the requirement of fastening down romex within 12" of the box? I would think so but I want to be sure before I go to far. My studs run horiziontal, so on the boxes between poles, I have a 17" length of wire going from the bottom of the stud above the box, into the box. Fastened at the stud above and then by the clamp connector, nothing in between but air. I'd rather not cut a bunch of short studs.

Charles (in GA)
06-11-2006, 01:22 PM
According to the examples given in my copy of Illustrated Guide to the National Electric Code, by Charles Miller (an excellent reference) the answer is NO. All wires have to be clamped in the box, one exception is NM wire in a single gange box, and then the wire must be clamped within 8 in of the box. In all other cases, for NM (romex), the wire has to be clamped in the box, and then within 12 in of the box, and every 4-1/2 ft after that. Cables running horizontally or diagonally thru framing members are considered supported and secured per the NEC provided the support intervals listed (4-1/2 ft for NM) are not exceeded.

If you are doing any amount of wiring at all, go to Amazon and buy the NEC and Miller's Illustrated Guide to the NEC, not cheap, but you get the real answers, not someone's opinion. Miller's books are considered the best teaching materials available for learning the Code, he has been in the NEC instruction business for many years and has spared nothing to make this book an excellent reference and learning guide.

Charles

Dave Carney
06-11-2006, 02:52 PM
Thanks Charles. I've got four electrical guide books, including Wiring Simplified, and Ugly's. Could not find a clear answer to this in any of them. On the main service entrance, that was done professionally, it's exactly the same situation, and the inspector passed it so I wasn't sure. But that's one box, I'm doing more like 20 more that will be like this. To, me the clamp is outside the box and thus fills the bill. I can see on those plastic nail on boxes why they would want that because there is no strain relief.

Dave Carney
06-11-2006, 03:13 PM
Heres some pictures, just in case anyone is interested. Each of the two outlets are the beginning of 2 seperate circuits. I stapled to the stud above the outlets, instead of the one below, because at 49" of height I didn't want the romex damage by someone (like me) laying something on it.

bmwpower
06-11-2006, 06:47 PM
I would have run the wires on the lower 2x4 instead. If you're concerned about damage, and you don't plan on finishing the inside walls, I would use armored cable or conduit.

But if you'd rather not do either of those 2 things, ask you inspector if he will OK what you're doing. The main idea behind the code ruling is to secure the wires. With your method, the wires are fairly secure. That may be all the inspector wants to see, but it's better to ask now then later.

Dave Carney
06-11-2006, 07:02 PM
Walls will be finished but probably not for five years. I'll just cut some 22.5" 2x4's and be done with it. I have enough scrap to cover half of them anyway. The rest will cost maybe $10 total. More work, but not much more. Just seemed like a waste of time for a single staple. That piece of #6 pre-wired armored coming out of the service panel is for my welder circuit. It was free, left over from a generator project.

Even though the surface of the lower stud is 1" above the "protection" level, I'm certain they would have failed me for that.

Charles (in GA)
06-11-2006, 07:06 PM
After seeing what you are doing (a picture IS worth a thousand words) I would be cutting a 2x4 or 2x6 and turning it flat to the purlins and flushing it in to them or recessing it and mounting the box on the two-by and boring holes thru these and the purlins and running the wire on the backside and on top of an upper purlin. The wires need protection from objects and people. Romex was not meant to be left exposed, expecially without being well secured.

Miller's Illustrated Guide to the National Electric Code ($50.23 Amazon price) and well worth it!!!!!!!!

http://www.amazon.com/gp/product/1401850685/sr=8-3/qid=1150073505/ref=pd_bbs_3/104-9009793-5490346?%5Fencoding=UTF8

The NEC itself in paperback ($72.50 Amazon price)

http://www.amazon.com/gp/product/0877656231/sr=8-1/qid=1150073505/ref=pd_bbs_1/104-9009793-5490346?%5Fencoding=UTF8

Charles

Dave Carney
06-11-2006, 07:30 PM
The 2x4 will sit behind the box (recessed), right in the space between the two wires, I left this space just for this reason, in case i needed a board in there. The purlins are 2x6 so, there is plenty of room for the 1.5" deep box and a 2x4 right behind it. I am trying for a bit of continuity with what the electrician has already done.

As it its now, it's plenty well secured, stapled at the top, clamped at the bottom, but I want it to meet the code, period, which is why I asked for clarification. Thanks guys.

Dave Carney
06-11-2006, 08:13 PM
Done. :beer:

Charles (in GA)
06-11-2006, 09:03 PM
Much better. Safer, stronger. looks better.

Charles

Dave Carney
06-12-2006, 06:58 AM
Yeah, it does look better. Not sure about the other two though. ;)