More 334 and Damp

[ivsenroute]

NM-B cable installed outdoors under patio/deck roof

Plain and simple, NM-B cable is not allowed in wet or damp locations. A large 16' x 32' roof over an attached open deck is no exception.

I routinely see NM cable run in this area and also fail the installation. It is outdoors and in a damp location. I cannot call it wet because it is inside the roof frame but it most certainly is damp. There is no reason why UF cable can't be run from the last device/box inside to the exterior of the home.

Is this enforced in your area or do you not put yourself in that position in the first place and use UF or another appropriate material?

 

[WinZip]

UF - Seal tite - PVC - but never NM cable.

 

[LarryFine]

I cannot call it wet because it is inside the roof frame but it most certainly is damp.

What about ventilated attics or crawl spaces?

 

[WinZip]

I don't know how to respond to those two questions.

 

[macmikeman]

Well now that you bring all this up, modern uf cable is pretty much about the same thing as romex from 1970. Uf back then was solid sheath all the way and a bear to strip. Most uf I buy nowadays is just about hollow on the inside like romex with no paper. A walk in the park to strip it now compared to what it used to be. By the way, I have worked my whole career around romex runs in open area carports, markee's and the like. None of it has ever suffered a tiny bit from the damp , except for rusted staples at times, but you will see that happen to staples supporting uf as much as staples supporting romex. Wet locations, I can see the concerns. Damp locations- CMP's need to get out to the field for at least ten minutes every decade or so and have a peek at the real world reality. Yeah, I know, ... I speak heresy. Go ahead and fire away, I'm used to it by now...

 

[hurk27]

NM-B cable installed outdoors under patio/deck roof

Plain and simple, NM-B cable is not allowed in wet or damp locations. A large 16' x 32' roof over an attached open deck is no exception.

I routinely see NM cable run in this area and also fail the installation. It is outdoors and in a damp location. I cannot call it wet because it is inside the roof frame but it most certainly is damp. There is no reason why UF cable can't be run from the last device/box inside to the exterior of the home.

Is this enforced in your area or do you not put yourself in that position in the first place and use UF or another appropriate material?

This was a wording change in 2008, where 2005 said:

334.10(B)(4)Where exposed or subject to excessive moisture or dampness

Which kind of left it up to the inspector judge as to how much is excessive, so it was allowed by inspectors in many cases in such locations as you described.

But it was changed in 2008 to:

334.10(B)(4) In wet or damp locations

so you can see why some are still running it under over hangs and porches

To me i have never seen a problem as long as its not an area that is constantly getting wet, if it is then the home owner is going to have a bigger problem with the wood getting wet and roting.

 

[ivsenroute]

I am not saying that I agree with the code change but that it is often overlooked on both the EC and EI ends.

Why the changes in code verbage over the years?
Is the material of lesser quality and that is the reason?

 

[insparks]

I guess this is not an approved location for this. I can hear the contractor say "but it's under the roof"

 

[elohr46]

NM-B cable installed outdoors under patio/deck roof

Plain and simple, NM-B cable is not allowed in wet or damp locations. A large 16' x 32' roof over an attached open deck is no exception.
I routinely see NM cable run in this area and also fail the installation. It is outdoors and in a damp location. I cannot call it wet because it is inside the roof frame but it most certainly is damp. There is no reason why UF cable can't be run from the last device/box inside to the exterior of the home.

Is this enforced in your area or do you not put yourself in that position in the first place and use UF or another appropriate material?

I agree if the roof has exposed joists, but if it is enclosed then it is no different than a roof eave, damp basement, crawl space, or attic space. IMO

 

[hurk27]

I am not saying that I agree with the code change but that it is often overlooked on both the EC and EI ends.

Why the changes in code verbiage over the years?
Is the material of lesser quality and that is the reason?

Not sure if it was about hurricane Katrina and the flooding of New Orleans, But there was a lot of scuttle butt around the IAEI and NFPA tables,(so I was told) on how many manufactures were still using a paper filler which can wick water easily up into the outer sheathing, I just don't see this happening in a location where hardly any water will get into the outlet box's up under a covered roof.

What about box's for outside light and receptacles? wired all the time with regular NM, but I can see these getting water in them much more easily, I see air disconnects all the time with 10/2 NM to it, again nothing over head to protect it from rain but the R-3 disconnect.

But I have never seen a failure because of water getting into the NM? in most cases water can not collect in these box's and drains out before even reaching the end of the sheathing.

But I have seen WP box's full of water, trapped by the very gasket that is supposed to keep it out, So I would say that the old code words had some merit as to allowing an inspector some allowance as to the installation of NM to some of these locations by just saying there is no easy way for the water to reach the end of the NM sheath in the box.

 

[LarryFine]

What about box's for outside light and receptacles? wired all the time with regular NM, but I can see these getting water in them much more easily,...

I always bring NM into exterior-wall boxes from the top KO(s).

I see air disconnects all the time with 10/2 NM to it, again nothing over head to protect it from rain but the R-3 disconnect.

Well, we do that with exterior panels, too. Apparently, the interior of exterior enclosures aren't considered wet locations.

But I have seen WP box's full of water, trapped by the very gasket that is supposed to keep it out, ...

I always drill a pair of 1/8" holes in the bottom of wall-mounted WP boxes, upward-pointed LB's, etc.