# NM-B "Romex" inside a pole barn as an accessory structure to a residence



## jar546

Is NM-B allowed to be exposed per the NEC 2008 & 2011 inside a pole barn that is an accessory structure to a single family residence?


----------



## fatboy

Are livestock being housed there? Potentialy?


----------



## jj1289

Need more information on the intended use of the building.  We get a lot of applications for "barns" and they are actually storage sheds or detached garages.  The applicant call them barns because they look like a barn.


----------



## jar546

fatboy said:
			
		

> Are livestock being housed there? Potentialy?


No but I don't see the relevance.  Educate me so I can eat another piece of humble pie today.


----------



## jar546

If it is not a dwelling unit but it is a type 3,4 or 5 construction, what is the relevance to the use other than more restrictions?

Would not 334.10(3) apply?


----------



## gfretwell

I see the issues as whether this is a dry location and the "exposed to physical damage" thing.

Animals with teeth can be your physical damage trigger but the question is always answered by an arbitrary decision.


----------



## jar546

I do not believe it is allowed regardless of the intent of use.  It is not a dwelling unit.


----------



## Gregg Harris

jar546 said:
			
		

> I do not believe it is allowed regardless of the intent of use.  It is not a dwelling unit.


334.10(3)

(3) Other structures permitted to be of Types III, IV, and V construction except as prohibited in 334.12. Cables shall be concealed within walls, floors, or ceilings that provide a thermal barrier of material that has at least a 15-minute finish rating as identified in listings of fire-rated assemblies.

Or could be protected if run on open studs

334.15 Exposed Work.

In exposed work, except as provided in 300.11(A), cable shall be installed as specified in 334.15(A) through ©.

(A) To Follow Surface. Cable shall closely follow the surface of the building finish or of running boards.

(B) Protection from Physical Damage. Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, Type RTRC marked with the suffix -XW, or other approved means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, Type RTRC marked with the suffix -XW, or other approved means extending at least 150 mm (6 in.) above the floor.


----------



## chris kennedy

Gregg Harris said:
			
		

> (B) Protection from Physical Damage.


My thought as soon as I read the thread title.

Whats a pole barn?

From wiki;

[h=3]Pole barns[/h] Main article: Pole building framing

 A pole barn in North America is a barn that is essentially a roof  extended over a series of poles. They are generally rectangular and do  not require exterior walls. The roof is supported by the poles, which  make up the perimeter of the barn.[8]  Walls may be added to pole barns but are not required for structural  integrity. The roof can be gabled or hooped. Pole barns are often used  for hay storage or livestock shelter, and larger structures are also used for indoor horse stables and riding arenas.  This type of barn is not only very common in modern agriculture but is  also used for other applications where large spaces are needed,  including boat and truck storage, warehouses, strip malls, retail  stores, public exhibit buildings at a fairgrounds,  and related uses. Residential garages are also built as pole barns  because of their quick construction time and efficient use of materials.

 The advantages of pole barns include their low cost and their ability to store large quantities of hay or other materials in areas easily accessible by vehicles, machines, and people.[9]

 In the United Kingdom a pole barn refers to a type of Dutch barn.


----------



## fatboy

Not serving any pie, I was thinking it being a potential corrosive atmosphere per 547.1 (B)(1), NMC is allowed.

My head hurts now that I've spent a half hour in the NEC. :banghd


----------



## jar546

Hmmmm, looks like we just may have ourselves a discussion.....................

I try not to ask black and white, easy questions for a reason.


----------



## BSSTG

Greetings,

No problem according to 334 and not exposed to physical damage. Would have to  be protected within 8' of the floor as I recall but that may be in an older Code. In Tx it's not uncommon for the Code to be amended so as to prohibit NM from anything but dwellings however.

BS


----------



## jwelectric

I see nothing wrong with the use of NM-B cable in a pole barn where it is not subject to corrosive fumes or vapors, see 334.12(B)(1)

334.10(A) Type NM. Type NM cable shall be permitted as follows:

(1)  For both exposed and concealed work in normally dry locations except as prohibited in 334.10(3)

If the pole barn is dried in there would be no problem even if it has a dirt floor. I have a barn that is 36 by 120 feet with NM-B that is used as a horse barn. The NM-B is not exposed to any weather and is above 10 feet of finish dirt floor


----------



## jar546

What I don't understand is that 334.10(3) does not prohibit anything, it is a "permitted" section except it refers to 334.12 which is "prohibited"


----------



## jar546

There was a change from 2008 to 2011 that clarified that detached garages and storage buildings were included.  This means they know the code is written to exclude NM and they changed the language to say it is OK.



> This section was revised for the 2011 _Code_ to clarify that the requirements for the use of nonmetallic-sheathed cable in garages of one- and two-family dwellings apply regardless of whether the garage is attached or detached. The same requirements also apply to detached sheds or storage buildings associated with one- and two-family dwellings.


So per 2008 NEC, NM is not allowed to be exposed in this situation but in the 2011 NEC due to the addition of the garage/storage language, it would be allowed.


----------



## BSSTG

Greetings,

One should always check to see if the specific occupancy type is listed in Chapter 5 of the NEC too. There have been some changes in the last few code cycles in Chapter 5 one of which is 520 with regard to use of NM (Assembly Occupancies). Bear in mind, Chapter 3 are general requirements where chapters 5,6, and 7 are more specific and may amend requirements in chapter 3 (see NEC 90.3).

BS


----------



## Gregg Harris

jar546 said:
			
		

> There was a change from 2008 to 2011 that clarified that detached garages and storage buildings were included.  This means they know the code is written to exclude NM and they changed the language to say it is OK.So per 2008 NEC, NM is not allowed to be exposed in this situation but in the 2011 NEC due to the addition of the garage/storage language, it would be allowed.


 Allowed to be used but not exsposed.


----------



## jar546

Gregg Harris said:
			
		

> Allowed to be used but not exsposed.


Not exposed in 2008

OK to be exposed 2011 except where subject to physical damage (subjective)


----------



## globe trekker

> Not exposed in 2008. OK to be exposed 2011 except where subject to physical damage (subjective)


So, if installing under the 2011 NEC, ..the installer could interpret "subject to physical damage"

in a manner that suits them (i.e. - below 8 ft. a.f.f., or anywhere else), and the heck with any

real safety concerns for the pole barn owner?

This sounds very familiar!

.


----------



## jar546

If it is inside & protected from the weather, whether a pole barn or residential detached garage or storage building in 2011 it can be left exposed except where subject to physical damage. (providing it is an accessory structure to a dwelling unit)

In 2008, it cannot be installed unless covered with a 15 minute rated material in those same areas.


----------



## moose

The Livestock question was a good one, refer to Art. 547 Agricultural Buildings in the NEC. Romex not allowed.

As far as a storage building, it is allowed by Art. 334.15


----------

