Codes & Standards
by Mark Henry, Inc. on 08/13/16
Manufactured Wiring
Systems (MWS) are field installed wiring using off-site manufactured
subassemblies for branch circuits, remote control circuits, signaling circuits,
and communications circuits in accessible areas. MWS are permitted in accessible and dry locations, in ducts,
plenums, and other air-handling space. Acceptable wiring methods include type
AC and MC cable, flexible metal or liquid tight conduit, hard use cords,
busway, and raceway. Permissible wiring methods shall be marked on each section
of MWS. Receptacles and connectors
used to feed MWS shall be the
polarized locking type, identified for the purpose, and designed to prevent
inadvertent contact with live part. All MWS
wiring methods shall be listed for the intended use [NFPA70:604].
Cables used in MWS shall be a) listed for use, b) type AC or MC, c) furnished with insulated copper conductors, rated 600 volts, sized between 12 AWG to 8 AWG, and d) equipped with an insulated or uninsulated equipment grounding conductor of equivalent size to the ungrounded conductor [NFPA70:604(A)(1)].
Conduits used in MWS shall be a) listed for use, b) flexible metal conduit or liquid tight flexible conduit, c) furnished with insulated copper conductors, rated 600 volts, sized between 12 AWG to 8 AWG, and d) equipped with an insulated or uninsulated equipment grounding conductor of equivalent size to the ungrounded conductor [NFPA70:604(A)(2)].
Cords used in MWS shall be a) listed for hard use, b) part of a listed factory-made assembly, containing insulated copper conductors sized 12 AWG minimum, equipped with an equipment grounding conductor of equivalent size to the ungrounded conductor, and include an identified strain relief c) of a length not exceeding 6 ft, and d) installed so that the cord shall be visible for the entire length [NFPA70:604(A)(3)]
Busway used in MWS shall be a) listed continuous plug-in type, b) provided with factory mounted, bare or insulated copper or aluminum conductor bars, rods, or tubes, b) provided with an equipment ground, c) rated 600 volts, d) sized 20, 30, or 40 amperes, and e) installed in accordance with NFPA70:365 Busways [NFPA70:604(A)(4)].
Raceway used in MWS shall be a) listed for use, b)
prewired, c) modular, d) surface mounted, e) rated 600 volts, f) sized 20
amperes, and g) installed in accordance with NFPA70:386 Surface Metal Raceways
[NFPA70:604(A)(5)].
