NM Cable and Damp Locations

[clausb]

Discussion here in the office about NM cable connecting to boxes/devices/luminaires in damp locations. In a building where NM cable is an acceptable wiring method, with one or two "damp location" spaces, if the NM is in the wall or hard ceiling, and feeds a luminaire or device in a properly rated enclosure, does the wiring concealed in the wall or ceiling have to be something other than NM? And if so, how far do you take this?

References, NEC 334-12(B)(4), NEC 312.2, NEC 100 definitions.

 

[Little Bill]

No it does not need to be "other than NM". Most outside lights or receptacles mounted on a house is fed from inside with NM. A few inches in a box does not mean the NM is in a damp location.

 

[jap]

No it does not need to be "other than NM". Most outside lights or receptacles mounted on a house is fed from inside with NM. A few inches in a box does not mean the NM is in a damp location.

That would be one of many opinions about this.

JAP>

 

[electrofelon]

That would be one of many opinions about this.

JAP>

I don't see how it is opinion. Code specifically declares inside raceways outside and underground wet location. There is no such declaration for boxes. If it's a listed wet location box, then the inside of the box is dry. If it wasn't then I'm not sure what the purpose of a listed outdoor box would be.

 

[steve66]

I can understand why there would be some controversy over this, but I agree with the other 2 posts. I think the inside of the box is a dry location.

Are the wire nuts commonly used inside these boxes listed for a wet or damp location?

 

[jap]

If it's a listed wet location box, then the inside of the box is dry. If it wasn't then I'm not sure what the purpose of a listed outdoor box would be.

And therein lies the problem.

Most residential projects I've witnessed have standard 4/0 metal or a Plastic box hanging off of a piece of NM for the outside outlets in preparation for the brick layer or siding guys to come along and install them.

Some NM protrusions simply go into a siding block with no box whatsoever much less a listed wet location box.

JAP>

 

[electrofelon]

And therein lies the problem.

Most residential projects I've witnessed have standard 4/0 metal or a Plastic box hanging off of a piece of NM for the outside outlets in preparation for the brick layer or siding guys to come along and install them.

Around here the siders and brick layers are not installing electrical boxes, and I don't see an issue with the finished product.

Some NM protrusions simply go into a siding block with no box whatsoever much less a listed wet location box.

JAP>

Sounds like a violation and hack job to me. The dry location only cable assembly would be the least of my concerns in such a situation.

 

[jap]

Around here the siders and brick layers are not installing electrical boxes, and I don't see an issue with the finished product.



Sounds like a violation and hack job to me. The dry location only cable assembly would be the least of my concerns in such a situation.

Around here it's done all the time.
The Electrician leaves a stubout of NM with a plastic or metal box hanging off of it.

The Brick Layers mud the boxes into the brick as they come to it for all outside lighting receptacles and lighting fixgtures.

JAP>

 

[jap]

You'll never see a WP box roughed into the brick in our area on a residential construction site.

JAP>

 

[jap]

Same goes with AC Pullouts.

The NM is stubbed out of the brick and the pullout mounted over it.

With a gap between the pullout and the brick, that cannot be considered a dry location with the NM no more than a wp box mounted to, or, in the brick in my opinion.

Even if a WP box is roughed into the brick, the strap that attaches to that box and the fixture that goes over the box is does nothing to keep the water out of the box, so, what do you gain by roughing in a wet location rated box?