where in the nec does it talk about multigang boxes? I looked in my old "99" book art 370 and "2002" art 314 it doesn't talk about multi gang boxes specifically internal clamps per securing not box fill. and a single gang exception if romex strapped within 8"
314.17(C) Nonmetallic Boxes and Conduit Bodies. Nonmetallic boxes and conduit bodies shall be suitable for the lowest temperature-rated conductor entering the box. Where nonmetallic boxes and conduit bodies are used with open wiring or concealed knob-and-tube wiring, the conductors shall enter the box through individual holes. Where flexible tubing is used to enclose the conductors, the tubing shall extend from the last insulating support to not less than 6 mm (¼ in.) inside the box and beyond any cable clamp. Where nonmetallic-sheathed cable or multiconductor Type UF cable is used, the sheath shall extend not less than 6 mm (¼ in.) inside the box and beyond any cable clamp. In all instances, all permitted wiring methods shall be secured to the boxes.
Exception: Where nonmetallic-sheathed cable or multiconductor Type UF cable is used with single gang boxes not larger than a nominal size 57 mm × 100 mm (2 ¼ in. × 4 in.) mounted in walls or ceilings, and where the cable is fastened within 200 mm (8 in.) of the box measured along the sheath and where the sheath extends through a cable knockout not less than 6 mm (¼ in.), securing the cable to the box shall not be required. Multiple cable entries shall be permitted in a single cable knockout opening.
Joe Tedesco, NEC Consultant
Re: multi gang boxes#92573 03/27/0511:02 AM03/27/0511:02 AM
Joe, what is meant by "open wiring" in Where nonmetallic boxes and conduit bodies are used with open wiring or concealed knob-and-tube wiring, the conductors shall enter the box through individual holes.? This isn't saying you can't install two NM-B cables into a single entry hole on a multi-gang non-metallic box is it?
Re: multi gang boxes#92575 05/12/0512:55 PM05/12/0512:55 PM
Read your NEC Articles, boys... it's all there if you look hard enough <smart aleck>
(Courtesy of the '96 NEC)
ART 320 - OPEN WIRING ON INSULATORS - Open wiring on insulators is aa exposed wiring method using cleats, knobs, tubes, and flexible tubing for the protection and support of single insulated conductors run in or on buildings, and not concealed by the building structure.
ART 324 - CONCEALED KNOB-AND-TUBE WIRING - Concealed knob-and-tube wiring - a wiring method using cleats, knobs, tubes, and flexible tubing for the protection and support of single insulated conductors
As far as multiple NM entries?
Read the Exception. It's plainly allowed.
Re: multi gang boxes#92576 05/12/0501:25 PM05/12/0501:25 PM
For some reason, I thought the words "single gang boxes" in the first sentence of the exception also referred to the final sentence of the exception. That's why I thought it would be odd that you could do it on a single gang box but not on a multi-gang box. Thanks for clearing it up.
Re: multi gang boxes#92577 05/12/0508:39 PM05/12/0508:39 PM
Joe Tedesco wrote: See last sentence of the Exception above: "Multiple cable entries shall be permitted in a single cable knockout opening."
Because it was a part of a single Exception, and the words "multi-gang" weren't mentioned anywhere, but the words "single gang" were, I thought that sentence was only referring to single gang boxes. The Exception is ambiguous and appears open to interpretation by the AHJ.
I was quite surprised when I read the actual code, because I thought I must have been doing it wrong (more than one cable entry per hole on a mutlti-gang box) all of this time.
[This message has been edited by royta (edited 05-13-2005).]
Re: multi gang boxes#92580 05/15/0507:03 PM05/15/0507:03 PM
What's the limit on the number of cables allowed through a single entry?
My experience has been "what will fit", based on my practice and no AHJ complaints ever. I routinely insert three 14/2's or 12/2's in a single-gang Carlon cable hole when they come from the same direction, such as feed-in/feed-out/switch-leg to a wall switch.
In fact, when roughing, I usually strip the two or three cables, strip the wires, hook those intended for screws, align the colors, "pre-twist" the grounds together (and any others to be joined) all before inserting them into the box, and then staple or stack.
To me, this is faster, and definitely neater, than any other way; especially compared to others I've seen who don't even strip the sheath before box insertion. Plus, I never mistake which wire is which (leg, travelers, etc.) I also label the cables inside the box.