Do I need a box clamp (wiring)

[farmerjoe]

This is a small barn with livestock in most of the building. In the back there is a separate room for feed and supplies (called feedroom). Animals dont go in there. On the wall adjoining the animals, there is an outlet with GFIC. I want to put an outlet in the actual barn directly behind this outlet. Because livestock chew wires, no wires can be exposed. The box is a metal handy box and will be connected downline form the GFIC. The wire will need to go thru two 2x4's nailed together and directly into a knockout on the rear of the handybox, which will be screwed to that 2x4. Thus, the length of wire from the "supply" box (in feed room) to the outlet in the animal section, is about 6 inches of 12-2 romex. There will be a romex clamp connector on the side of the box in the feed room. The wire goes the

6 inches thru the wall and directly into the box in the animal room. My question is whether I need a cable clamp on the rear of the handybox in the animal section? In order to fit the clamp with it's screws into the wall, I'd need to drill a hole about 1 1/4 inches in diameter. Not only is this a big job to drill, but also will weaken the wall. For such a short run of wire is it absolutely necessary to use a clamp, or should I just push the wire thru the knockout, ground it to a green screw, and wire to the outlet. Remmember, it's clamped in the feed room, 6 inches away.

I do know that it would electrically work without the clamp and poses no real hazzard, but how would the code look at this? I doubt it will ever be inspected where I live, but I am just checking on what is required.

I have also considered using a 4.5 inch box for that outlet and putting the clamp on the INSIDE of the box, in a corner where it wont be near the outlet. I always use clamps where all wires enter boxes, but in this case it seems rather senseless and much more trouble than it's worth.

What would you do? What is allowed?

Thanks

Farmer Joe

[RBM]

If it's acceptable to use a handy box, you could use a connector like the "Arlington Button", which is a small plastic insulator disk that snaps into the knockout. You should check with local authorities to be sure a weatherproof box like a bell box would not be required in an agricultural building

[David Martel]

Joe,

I don't know your code so I'm guessing here. If you are supposed to wire livestock areas with clamps and this job is in a barn then use a clamp. That you use the room now for storage does not mean that the room won't be used for livestock in the future.

Dave M.

[dpb]

What kind of livestock first? How high is this outlet? What kind of outlet are you planning on?

In a barn w/ horses particularly I would never leave exposed wiring (as in recpetacles/switches/etc where they can get to them on a continuous basis (that is, when you're not there in an enclosure they have free rein in). In an area of occasional pass-thru use, that's different.

If it needs to be in such a location, imo it should be recessed somehow either with a framed box or a purchased cage sufficient to prevent damage.

I'll leave the code question to the code gurus although I _think_ code requires a cable be fastened at the entrance to any box. If you can't find a suitable box w/ an integral clamp, the problem in many boxes that code doesn't like is that when you punch the hole that leaves a sharp edge which can potentially cut the insulation so must ensure a smooth, burr-free entrance. I don't believe there's any reason a cable staple at the rear of the box wouldn't suffice.

As for what I'd do, I'd assess the sittyashun and figure out something I was pleased with and be done w/ it, knowing intent of Code...

--

[Chris Lewis]

According to :

You _always_ need a clamp or bushing on a box to protect the wire from chafing on the sharp edges of the knockout.

Mounting the clamp on the inside should suffice. Use a cast clamp with a ring nut, ring nut on outside. You may need to drill out a shallow divot with a diameter of 1 1/4" or so to clear the threads and nut, but the rest need only be enough for the wire.

The spreading metal clamps might work too on the inside.

The other option would be a 90 degree elbow clamp. Comes out the side, and the elbow goes straight into the wall a bit, so no sheath is exposed.

Or a short sheath of PVC electrical conduit. H'm, maybe it needs to be metal.

[RBM]

Here is a link: