Article 334 (336 in 1999 NEC)
334.10 Uses Permitted
This subsection was completely revised to read:
Type NM and NMC cables can be used in any of the following occupancies:
Intent: This removes the long standing rule that prohibits NM cable in buildings over 3 stories. The new language permits NM cable to be installed in any buildings and structures of combustible construction (Type III, IV, and V construction).See Appendix E in the back of the Code book for the definitions of construction types.
(1) One and Two-Family dwellings.
(2) Multifamily dwellings of Type III, IV, and V construction, except as prohibited in Section 334.12. Figure 334–1
(3) In other structures of Type III, IV, and V construction (except as prohibited in Section 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.
The number of floors varies according to the specific construction type, the fire resistance rating subdivision of the construction type, the nature of the occupancy, as well as the presence of other fire protection features such as automatic sprinklers. For example:
FPN No. 1: Building construction types are defined in NFPA 220 - Standard on Types of Building Construction or the applicable building code or both.
- Apartment –Type VB construction can be 3 stories above grade, 4 stories if sprinklered.
- Business – Type IIIA construction can be 5 stories above grade, 6 stories if sprinklered.
- Hotel – Type IIIB construction can be 4 stories above grade, 5 stories if sprinklered.
- Retail – Type IV construction can be 4 stories above grade, 5 stories if sprinklered.
- Storage – Type IIIB construction can be 4 stories above grade, 5 stories if sprinklered.
FPN No. 2: See Annex F for determination of building types (Table 3-1 from NFPA 220).
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