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NM-B cable installed outdoors under patio/deck roof

jar546

jar546

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Plain and simple, NM 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.

Does anyone else enforce this? I make some EC's and homeowners very unhappy because of this.
 
jar546,

I'm with you until you listed UF-Underground Feeder cable. Conduit would be the best way to meet the code, IMO.

340.10 (3) allows it if wired to code.

pc1
 
So what makes it damp?

My bathroom has high humidity - longer and higher than the location shown has. Can I use NM in my bathroom.

My basement has high humidity. Can I run NM through my basement?

What is your objective measure of "damp."

I would use NM there. The wire inside of the sheathing is listed for damp locations but is not marked on the wire. The sheathing certainly does its work despite the dampness.
 
The NEC definition of damp location includes locations such as "...under canopies, marquees, roofed open porches..."

It's a violation, so I am not able to approve it.
 
The NEC is very clear that the inside of conduit outside of the building is considered a damp and the inside of conduit that is below grade is considered a wet location so why wouldn't the outside itself be considered damp?
 
To answer jar's question: electrical inspectors here have not allowed NM outdoors at all for the past 20 years.

Also, I don't believe NM is sunlight resistant, whereas UF is? May not pertain to this situation. And I may be completely wrong :)
 
So why can I run NM in my bathroom, laundry, basement, or crawlspace? All are as damp as under the canopy.

More importantly why do you let others run NM in those locations?
 
We allow NM if it is fully enclosed in the roof of the porch. Not a damp location in my opinion. It sounds like we may be wrong though. I would like to hear more opinions from the sparkys.
 
Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.
Click to expand...
334.12 Uses Not Permitted.(A) Types NM, NMC, and NMS. Types NM, NMC, and NMS cables shall not be permitted as follows:

(1) In any dwelling or structure not specifically permitted in 334.10(1), (2), and (3)

Exception: Type NM, NMC, and NMS cable shall be permitted in Type I and II construction when installed within raceways permitted to be installed in Type I and II construction.

(2) Exposed in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings

(3) As service-entrance cable

(4) In commercial garages having hazardous (classified) locations as defined in 511.3

(5) In theaters and similar locations, except where permitted in 518.4(B)

(6) In motion picture studios

(7) In storage battery rooms

(8) In hoistways or on elevators or escalators

(9) Embedded in poured cement, concrete, or aggregate

(10) In hazardous (classified) locations, except where permitted by the following:

a. 501.10(B)(3)

b. 502.10(B)(3)

c. 504.20

(B) Types NM and NMS. Types NM and NMS cables shall not be used under the following conditions or in the following locations:

(1) Where exposed to corrosive fumes or vapors

(2) Where embedded in masonry, concrete, adobe, fill, or plaster

(3) In a shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar finish

(4) In wet or damp locations
Click to expand...
This sparky says violation.
 
chris kennedy said:
This sparky says violation.
Click to expand...
Now define a damp location.
emot105.gif
 
* * *

480sparky & GHRoberts asked:

Now define a damp location.
emot105.gif
Click to expand...
Mac has given a partial answer. From the 2006 IRC, Ch. 34, Section 3401 -"LOCATION, DAMP. Location protected from weather and not subject to saturation

with water or other liquids, but subject to moderate degrees of moisture. Examples

of such locations include partially protected locations under canopies, marquees,

roofed open porches and like locations, and interior locations subject to moderate

degrees of moisture, such as some basements, some barns and some cold-storage

warehouses."

From the 2006 IRC, Ch. 2 - Definitions, Section R201.4 - Terms not defined.

"Where terms are not defined through the methods authorized by this section,

such terms shall have ordinarily accepted meanings such as the context implies."

From Underwriters Laboratories - UL Definitions, From UL Standard

Publication 1598.

Dry Locations: "A location not normally subject to dampness, but may

include a location subject to temporary dampness, as in the case of a

building under construction, provided ventilation is adequate to prevent

an accumulation of moisture."

Damp Location:

"An exterior or interior location that is normally or periodically

subject to condensation of moisture in, on, or adjacent to,

electrical equipment, and includes partially protected locations."

Wet Locations:

"A location in which water or other liquid can drip, splash,

or flow on or against electrical equipment."

Hope this helps! :cool:

* * *

 
If the porch roof has a fully enclosed ceiling is that a damp location??? That is what I am talking about. I can see no NM in an open porch with just a roof and exposed rafters (partially protected areas per definition above) but if you put in the ceiling it is OK in my book.
 
So now we all agree that bathrooms are damp locations. No NM run to bathrooms.

No NM in laundry rooms.

No NM in kitchens.. (All the boiling water cannot be good.)
 
I agree, you cannot run NM exposed in the damp location such as bathrooms, laundry rooms and kitchens.

If we are talking about wires concealed in the framing, I don't believe that is in the damp location.
 
George,

I do not believe that a bathroom, a laundry or kitchen has a ' moderate ' amount of moisture

accumulating on any NM wiring. The exhaust fans and the HVAC return air would diminish

the moisture, yes? Also, wouldn't the NM wiring be installed behind the gyp. board ( i.e.

- a covered install ) ?

.
 
Globe,

George stated that the NM cable was inside "his" bathroom; and, I don't doubt it;

" So why can I run NM in my bathroom "

NM cable is pretty sturdy. Stretched across the room; you could hang your towels and wash cloths on it.

Uncle Bob
 
Any how ...

My concern about NM cable and damp locations is that the sheathing is sufficient to keep water out in damp locations. So I see no basis for not allowing NM in damp locations.

I see a rational reason for not allowing the sheathing to be removed (in boxes or at equipment) in damp locations as moisture can wick up the paper filler. But that is different than having runs of cable.

But ...
 
I am going to be building a house where the vanity sits on legs up off of the floor and will have the outlet in the side of it. I planned to come up through the floor inside the vanity with blue flex conduit into the box mounted inside the cabinet. Since the NM cable would be inside the conduit, do those of you who say you cannot have NM in a bathroom believe having it inside the conduit would be the same as having it inside a wall and would you pass this?
 
300.9 Raceways in Wet Locations Above Grade.

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 310.8©.

The location in the question above is not wet
 
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