NM Cable Use

[designer82]

Section 334.10 allows NM cable in dwelling units and Multi-Family and also in "Other" structures of Wood construction 334.10(3).

Section 334.10(A)(1) says it is ok to be installed exposed except as prohibited in 334.10(3).

My personal understanding of the above is , It's ok installed exposed in basements of dwellings but not ok in basements of Non-Dwellings

Please correct if I misunderstand, Thank you

 

[petersonra]

Section 334.10 allows NM cable in dwelling units and Multi-Family and also in "Other" structures of Wood construction 334.10(3).

Section 334.10(A)(1) says it is ok to be installed exposed except as prohibited in 334.10(3).

My personal understanding of the above is , It's ok installed exposed in basements of dwellings but not ok in basements of Non-Dwellings

Please correct if I misunderstand, Thank you

It does not say anything about being of wood construction, at least in the 2017 edition.

 

[Dennis Alwon]

The 2020 doesn't either

Type NM and Type NMC cables shall be permitted to be used in the following, except as prohibited in

334.12:

• (1)
  One- and two-family dwellings and their attached or detached garages, and their storage buildings.
• (2)
  Multi-family dwellings permitted to be of Types III, IV, and V construction.
• (3)
  Other structures permitted to be of Types III, IV, and V construction. 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.
  Informational Note No. 1:
  Types of building construction and occupancy classifications are defined in NFPA 220-2018, Standard on Types of Building Construction, or the applicable building code, or both.
  Informational Note No. 2:
  See Informative Annex E for determination of building types. [NFPA 220, Table 4.1.1]
• (4)
  Cable trays in structures permitted to be Types III, IV, or V where the cables are identified for the use.
  Informational Note:
  See 310.14(A)(3) for temperature limitation of conductors.
• (5)
  Types I and II construction where installed within raceways permitted to be installed in Types I and II construction

 

[designer82]

Section 334.10(3) - [Uses Permitted] states...
"Other Types Ill, IV, and V construction buildings where the cable
must be concealed within walls, floors, or ceilings that provide a
thermal barrier of material with at least a 1 5-minute finish rating
as identified in listings of fire-rated assemblies"

And then Section 334.15(C) [Exposed work] states..

"In Unfinished Basements and Crawl Spaces. lf Type NM cable
is installed at angles with joists in unfinished basements and crawl
spaces, it can be secured to cables containing conductors not smaller
than two 6 AWG or three 8 AWG conductors directly to the lower edges
of the joists. Smaller cables must be installed through bored holes in
joists or on running boards."

 

[Dennis Alwon]

Joist can be metal and so could a running board. I think you are over interpreting

 

[designer82]

"Other... where the cable must be concealed within walls, floors, or ceilings"
So does this mean that in "Other" it has to be concealed and cannot be run exposed in basement?

 

[petersonra]

"Other... where the cable must be concealed within walls, floors, or ceilings"
So does this mean that in "Other" it has to be concealed and cannot be run exposed in basement?

I am inclined to agree that it has to be concealed in other than dwelling units, since it pretty much says that. it still does not prohibit NM in other than wood frame construction. Look carefully at what it actually says and not what you think it means.