PERMISSIBLE CONSTRUCTION TO USE TYPE NM …

1 PERMISSIBLE CONSTRUCTION TO USE TYPE NM CABLEThis article is an interpretation of the 2002 national Electrical code regarding NM Cable. Please verify this information with all local inspection Science Park DriveCleveland, Ohio 44122216-464-34001-800-3 CARLON (322-7566) : David H. KendallIntroductionThe 2002 national Electrical code (NEC) is permitting the use of Nonmetallic Sheathed(NM) cables to be installed in buildings (structures) with heights higher than threestories. The intent of this article is to better understand the height limit of these buildingsbased on the language found in Section of the use of Type Nonmetallic Sheathed (NM) cable is regulated by both building andelectrical codes for most occupancies.

2 Codes and standards that address specifichazards may also regulate cable types and cabling methods in areas where thosehazards majority of jurisdictions in the United States use a version of the national ElectricalCode (NEC). The most current edition is the 2002. Many jurisdictions are using oldereditions, typically either the 1996 or the 1999 edition. The International code Council-Electrical code (ICC-EC), first published in 2000, adopts the NEC 1999 edition withamendments. To further complicate the situation, it is not unusual for local jurisdictionsto amend the electrical code or the building code as part of the adoption Being UsedIn order to determine if Type NM cable may be used, the applicable building and/orelectrical codes and edition must be identified.

3 Typically a call to the local BuildingOfficial or Plans Review Office will yield the needed information. Be sure to not only ask,what version of the electrical code is enforced, but ask if local amendments have beenadopted. Local amendments may revise either the building and/or the electrical amendments can make either code more or less codes do not directly regulate cabling types . The building code typically willreference the electrical code . The building codes may indirectly regulate cabling : Some of the electrical codes provisions limit cabling type based uponconstruction type. The building code limits CONSTRUCTION type based on occupancy,building height and building area.

4 Effectively the building code requirements, in thatcase, limit the wiring Automation (877) 268-3700 CONSTRUCTION TO USE TYPE NM CABLEThis article is an interpretation of the 2002 national Electrical code regarding NM Cable. Please verify this information with all local inspection Science Park DriveCleveland, Ohio 44122216-464-34001-800-3 CARLON (322-7566) 1 summarizes the code requirements of the NEC (1996 and 1999 editions) andICC-EC (2000 edition and 2001 and 2002 supplements) as well as the BOCA NationalBuilding code (BNBC) and the ICC International Building code (IBC) regulating the useof Type NM 2 lists the largest buildings that Type NM cable may be used based on therequirements of NEC 2002 edition and the CONSTRUCTION type limits in the InternationalBuilding code (IBC).

5 This table would be different if a different building code is used, orif a different edition of the IBC is used, or if local amendments alter the heights andareas Electrical code NEC (also know as NFPA 70)Section 336-4 of NEC 1996 and 1999 edition allows Type NM cable to be used in anybuilding 3 stories or less in height provided the building does not contain unusualhazards. Section 336-5 prohibits Type NM cable in any building of four or more NEC 2002 allows Type NM cable in any building that can be built ofcombustible CONSTRUCTION as defined by the building code . Combustible CONSTRUCTION isdescribed in most building codes as Type III, IV, or V CONSTRUCTION .

6 CONSTRUCTION type islimited by three factors: building height, floor area, and type of occupancy. Buildingsbuilt of noncombustible CONSTRUCTION ( types I and II) may use Type NM cable if thebuilding code will allow the building to be built of combustible CONSTRUCTION . Example: A4-story apartment building (R-2) with a floor plate of 15000ft2 built of Type 2 constructionmay use Type NM Cable, since the building could have been built of Type III, IV, or the building is protected throughout by an approved automatic sprinkler system,Section IBC allows the height limits in Table 2 to be increased by 20 feet and onestory. Section 506 IBC also allows the area to increases up to 350% of the table limits, ifopen perimeter and sprinkler requirements are followed.

7 See the IBC for several areamodification Automation (877) 268-3700 CONSTRUCTION TO USE TYPE NM CABLEThis article is an interpretation of the 2002 national Electrical code regarding NM Cable. Please verify this information with all local inspection Science Park DriveCleveland, Ohio 44122216-464-34001-800-3 CARLON (322-7566) 1 General Not PermittedP PermittedType NM cable may be installed exposed (Section of the 2002 NEC, Section 336-4 of the 1996 and 1999 NEC) 1 One- or two-family dwellings of any height may use Type NM (Section 336-4)2 Not including specific locations such as flammable or combustible liquids storage areas or wet locations For Assembly and Institutional facilities refer to the code4 Apartment (R-2)

8 Buildings onlyNECICC-ECBOCA-BNBCICC-IBC19961999200 02001 Supplement2002 Supplement199619992000 ConstTypeStoriesSectionSectionSectionSec tionSectionAny3 , 2, 3 AnyMorethan limit checkreferencedElectrical limit by checkreferencedElectrical Automation (877) 268-3700 CONSTRUCTION TO USE TYPE NM CABLEThis article is an interpretation of the 2002 national Electrical code regarding NM Cable. Please verify this information with all local inspection Science Park DriveCleveland, Ohio 44122216-464-34001-800-3 CARLON (322-7566) 2 MAXIMUM STORIES AND AREASB ased on NEC 2002 and IBC 2000 TYPE OF CONSTRUCTIONLOCATIONTYPE ITYPE IITYPE IIITYPE IVTYPE VAABABHTABH eight limitations (ft)6565556555655040 GROUPEXAMPLEPERMITTED MAX STORIES AND MAX AREAS/FLOOR (ft_)

9 BOffices536,000536,000423,000528,500419, 000536,000318,00029,000 ESchools325,500325,500214,500323,500214, 500325,500118,50019,500F-1 ModerateHazard FactoryMachine Shop433,500425,000215,500319,000212,0004 33,500214,00018,500F-2 Low HazardFactoryBrick, Gypsum550,500537,500428,500428,500318,00 0550,500321,000213,000 MRetail420,500420,500412,500418,500412,5 00420,500314,00019,000R-1 Hotels424,000424,000416,000424,000416,00 0420,500312,00027,000R-2 Apartments424,000424,000416,000424,00041 6,000420,500312,00027,000R-3 Townhouses4UL4UL4UL4UL4UL4UL3UL3 ULR-4 Small GroupHomes424,000424,000416,000424,00041 6,000420,500312,00027,000S-1 Warehouse326,000326,000317,500326,000317 ,500425,500314,00019,000S-2 Warehouse439,000439,000426,000439,000426 ,000538,500421,000213,500 UBarns, OutBuildings418,000414,00028,500314,0002 8,500418,00029,00015,500 General Notes:This table is based on Section of NEC 2002 edition and IBC Table 503 2000 that are under the limits in this table may use Type NM Cable (Section )Area limits are per limits may be increased by one-story when protected by automatic limits may be increased up to 350% of the table values if open perimeter and automaticsprinkler requirements are and two-family dwellings may use Type NM Cable (Section ).

10 Gross Automation (877) 268-3700 CONSTRUCTION TO USE TYPE NM CABLEThis article is an interpretation of the 2002 national Electrical code regarding NM Cable. Please verify this information with all local inspection Science Park DriveCleveland, Ohio 44122216-464-34001-800-3 CARLON (322-7566) code Council Electrical code (ICC-EC)The ICC-EC 2000 edition adopts the NEC 1999 edition without modifying the previsionsrelating to Type NM cable. Type NM cable may be used in any building 3 stories or lessin height provided the building does not contain unusual hazards. Type NM cable maynot be used in any building of four or more of the ICC-EC 2001 supplement modifies the NEC 1999 provisions toallow Type NM cable in 4-story apartment buildings.