What am I missing... Romex not outside?

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wrobotronic

wrobotronic

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Colorado
This may be the dumbest thing I have ever asked on here....please keep your ridicule to yourselves...

334 states NM cable is not allowed in damp or wet locations... How is it, then, that we run it in bathrooms, kitchens, and for outside lighting and recepts?

I was told that a run I had running across an attic, I was going to put the romex in emt and down the side of the house to the panel, had to mount a box and put THHN in the pipe be cuz romex was not allowed outside (wet/damp locations)..

I'm just not sure what I am missing here. It is clearly something though...

Thank you all....
 
NM running in walls is not in a damp area.
NM running exposed outside but protected from direct rain etc. may be considered a dry area.
But, because of condensation, the inside of a raceway exposed to temperature changes outdoors is considered to be wet.

mobile
 
If your kitchen or bathroom is a damp or wet location you either just had your roof ripped off by a tornado or you are living in some kind of non traditional housing.

The inside of an exterior raceway is defined as a wet location by the NEC no matter how dry it is so that is a lot easier to nail down.
 
It does not sound reasonable but the interior of the conduit mounted on the outsde wall of the building is wet/damp location.
You may debate that NM cable is ok to be subject to some dampness but.... it is not worth the trouble.
 
ActionDave said:
If your kitchen or bathroom is a damp or wet location you either just had your roof ripped off by a tornado or you are living in some kind of non traditional housing.

The inside of an exterior raceway is defined as a wet location by the NEC no matter how dry it is so that is a lot easier to nail down.
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How is a bathroom not at least damp? There are several rules for fixtures above tubs for example.

So then what I am ascertaining here is that drywall, tape and mud will then make the cavity in which the NM is ran a dry location?

However, the reference to the pipe definition is helpful and clears up the reason for the need for THHN...

Again, thank you....


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wrobotronic said:
How is a bathroom not at least damp? There are several rules for fixtures above tubs for example.

So then what I am ascertaining here is that drywall, tape and mud will then make the cavity in which the NM is ran a dry location?

However, the reference to the pipe definition is helpful and clears up the reason for the need for THHN...

Again, thank you....


Sent from my SM-G930V using Tapatalk
Click to expand...

You meant THWN.
 
Look at the NEC definition of 'Damp Location":

Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture.
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If your bathroom is not protected from the weather or subject to saturation with water, then you'd better call a roofer or a plumber. If you consider steam from hot water to be 'moderate degrees of moisture', then you'll start to get science projects growing.

Informational Note: This is sarcasm.
 
wrobotronic said:
How is a bathroom not at least damp? There are several rules for fixtures above tubs for example.
Click to expand...

"Inside" the bathroom can certainly be a damp and some parts even wet locations.

So then what I am ascertaining here is that drywall, tape and mud will then make the cavity in which the NM is ran a dry location?
Click to expand...

That is correct, if the interior of the wall is / was a damp location something is wrong and needs to be corrected.
 
wrobotronic said:
How is a bathroom not at least damp? There are several rules for fixtures above tubs for example.

So then what I am ascertaining here is that drywall, tape and mud will then make the cavity in which the NM is ran a dry location?

However, the reference to the pipe definition is helpful and clears up the reason for the need for THHN...

Again, thank you....
Click to expand...

In general a bathroom is a dry location with some exceptions like for lighting fixtures in the tub and shower zone. If it weren't then all receptacles and switches would require these:

6862734_Cooper_1gangGFCI_VertOutletCover_600sq.jpg
 
No ridicule. This topic comes up often. The problem with NM cable is that the wire ratings are marked on the outer sheath and as such can only be installed inside walls and in dry locations (and JB's for switches and receptacles with device covers on in bathrooms are still considered dry locations). The internal wiring in NM is also wrapped in a cardboard-like paper. It is possible that condensation could weep through the jacket and dampen the paper wrap and possibly corrode the wire over time. Now, if you look at MC cable, in contrast, the individual wires are marked before the armor goes on. So, my gripe is with manufacturers, and I'm sure it's a cost of production thing, but why can't they mark the wires or use THHN II before installing the sheathing ? That way, if you run the internal wiring say to an AC disconnect you can then use the same wires inside the whip to the unit.

Anyway, I would say that if you intend to install wiring in PVC on the outside of the house, use UF cable to solve that problem.
 
Here is the code section for aboveground.

300.9 Raceways in Wet Locations Abovegrade. Where
raceways are installed in wet locations abovegrade, the interior
of these raceways shall be considered to be a wet location.
Insulated conductors and cables installed in raceways in wet
locations abovegrade shall comply with 310.1 O(C).
Click to expand...

In other words, if the raceway is in a wet location the NEC considers the conductors inside it to also be in a wet location.

And while I am at it here is the section for underground

300.5 Underground Installations.

(B) Wet Locations. The interior of enclosures or raceways
installed underground shall be considered to be a wet location.
Insulated conductors and cables installed in these enclosures
or raceways in underground installations shall comply
with 310.10(C). Any connections or splices in an underground
installation shall be approved for wet locations.
Click to expand...
 
user 100 said:
What ActionDave means is that straight plain vanilla THHN is not listed for damp/ wet locations.
Click to expand...

And that there isn't too much of it (straight rated THHN) around anymore, most modern insulation is dual rated THHN/THWN.
 
infinity said:
And that there isn't too much of it (straight rated THHN) around anymore, most modern insulation is dual rated THHN/THWN.
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I don't think I have ever seen single rated THHN. It is probably a regional thing, but up north here I think everything has been dual rated for at least 35 years.
 
jim dungar said:
I don't think I have ever seen single rated THHN. It is probably a regional thing, but up north here I think everything has been dual rated for at least 35 years.
Click to expand...

I ended up editing my post earlier (thats why it appears different) after double checking the book on thhn- it seems it is listed for damp, not wet. Just never have given it much thought because I havent needed to. Usually do nm (which is run only in dry) or UF and when doing wire in pipe (which is rare)- its the dual rated stuff.

Seems that "damp only rated" single THHN conductors would actually be kind of useless- who wants to keep another product laying around when you have other stuff that covers that and more.:)
 
wrobotronic said:
How is a bathroom not at least damp? There are several rules for fixtures above tubs for example.

So then what I am ascertaining here is that drywall, tape and mud will then make the cavity in which the NM is ran a dry location?

However, the reference to the pipe definition is helpful and clears up the reason for the need for THHN...

Again, thank you....


Sent from my SM-G930V using Tapatalk
Click to expand...
Then why wouldn't all exterior walls be considered at least a damp location?
 
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