Cut Sheet

Non-Metallic Sheathed Cable Fittings
NOTE:
The materials herein, whether relating to the National Electrical Code, the Underwriters Laboratories, Inc. listing, to industry practice or otherwise,
are not intended to provide all relevant information required for use and installation of our products. Refer to applicable codes, instructions and
industry specifications prior to installation or use.
Non-Metallic Sheathed Cable
Ref. NEC Article 336
Code defines non-metallic sheathed cable as, “A factory assembly of two
or more insulated conductors having an outer sheath of moisture resistant,
flame retardant, non-metallic material.”
Non-metallic sheathed cable is constructed of insulated conductors
(14 to 2 AWG Copper or 12 to 2 AWG Aluminum or Copperclad Aluminum),
and an outer non-metallic sheath classified as Type NM or Type NMC.
Non-metallic sheathed cable is provided with or without a bare or insulated
equipment grounding conductor. Non-metallic sheathed cable is rated
for 60° C service with voltage limitation of 600 volts.
Type NM — has flame-retardant moisture resistant sheath.
Type NMC — has flame-retardant, moisture-resistant, fungus-resistant
and corrosion-resistant sheath.
Non-metallic sheathed cable is permitted by code to be used exposed
or concealed in one, two or multifamily dwellings or other structures
not exceeding three floors. Use of Type NM cable is restricted to dry
locations where as Type NMC can be used in dry, moist, damp or
corrosive environments.
Non-metallic sheathed cable (both Type NM & NMC) is not permitted
to be used as a service conductor, in commercial garages, in hoists
or cannot be embedded in cement, concrete or aggregate. With minor
exceptions use of non-metallic sheathed cable is also prohibited in
theaters or any hazardous locations.
NEC Section 336-5 requires that cable be secured in place by suitable
means so as not to injure the cable. Adequate protection for cable is
also required when run is exposed, through joists or rafters, through
floors, in unfinished basements and accessible attics.
Cable bends are limited to a minimum of five times the diameter
of the cable.
NEC 300-4(b) requires that cable be protected from physical damage when
it passes through factory or field punched, cut or drilled holes in metal
members. A bushing or grommet firmly secured in place is recommended.
Portions of this section reprinted by permission from NFPA 70-1999,
National Electrical Code
®
.
Copyright © 1977, National Fire Protection Association, Boston, MA.
Please refer to the following for further details
and complete information:
1. NEC Article 336…Non-Metallic Sheathed Cable (Type NM & NMC)
2. NEC Article 300…Wiring Methods
3. UL 719, ANSI C33.56…Safety Standards for Non-Metallic
Sheathed Cable
4. UL 514B, Safety Standards for Outlet Boxes and Fittings
5. NEMA FB-1…Standards Publication. Fittings and Supports
for Conduit and Cable Assemblies
6. CEC Section 12-600…Wiring methods (Non-Metallic Sheathed Cable)
7. CSA C22.2 No. 48…Safety Standards for Non-Metallic Sheathed Cable
8. CSA C22.2 No. 18…Safety Standards for Outlet Boxes,
Conduit Boxes and Fittings
A-162
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