limitations would exceed those for which the nonmetallic wireway is listed
I. General
378.21 Size of Conductors. No conductor larger than that for which the nonmetallic wireway is designed shall be installed in any nonmetallic wireway.
378.22 Number of Conductors. The sum of cross- sectional areas of all contained conductors at any cross section of the nonmetallic wireway shall not exceed 20
378.1 Scope. This article covers the use, installation,
and construction specifications for nonmetallic
wireways and associated fittings.
378.2 Definition.
Nonmetallic Wireways. Flame retardant, nonmetallic troughs with removable covers for housing and protecting electrical wires and cables in which conductors are laid in place after the wireway has been installed as a complete system.
378.6 Listing Requirements. Nonmetallic wireways and associated fittings shall be listed.
II. Installation
378.10 Uses Permitted. The use of nonmetallic wireways shall be permitted in the following:
(1) Only for exposed work, except as permitted in 378.10(4).
(2) Where subject to corrosive environments where identified for the use.
(3) In wet locations where listed for the purpose.
FPN: Extreme cold may cause nonmetallic wireways to become brittle and therefore more susceptible to damage from physical contact.
(4) As extensions to pass transversely through walls if the length passing through the wall is unbroken. Access to the conductors shall be maintained on both sides of the wall.
378.12 Uses Not Permitted. Nonmetallic wireways shall not be used in the following:
(1) Where subject to physical damage
(2) In any hazardous (classified) location, except as permitted by other articles in this Code
(3) Where exposed to sunlight unless listed and marked as suitable for the purpose
(4) Where subject to ambient temperatures other than those for which nonmetallic wireway is listed
(5) For conductors whose insulation temperature
percent of the interior cross-sectional area of the nonmetallic wireway. Conductors for signaling circuits or controller conductors between a motor and its starter and used only for starting duty shall not be considered as current-carrying conductors.
The derating factors specified in 310.15(B)(2)(a) shall
be applicable to the current-carrying conductors up to
and including the 20 percent fill specified above.
378.23 Insulated Conductors. Insulated conductors in stalled in a nonmetallic wireway shall comply with
378.23(A) and (B).
(A) Deflected Insulated Conductors. Where insulated conductors are deflected within a nonmetallic wireway, either at the ends or where conduits, fittings, or other raceways or cables enter or leave the nonmetallic wireway, or where the direction of the nonmetallic wireway is deflected greater than 30 degrees, dimensions corresponding to one wire per terminal in Table 312.6(A) shall apply.
(B) Nonmetallic Wireways Used as Pull Boxes. Where insulated conductors 4 AWG or larger are pulled through a wireway, the distance between raceway and cable entries enclosing the same conductor shall not be less than that required in 314.28(A)(1) for straight pulls and in 314.28(A)(2) for angle pulls. When transposing cable size into raceway size, the minimum metric designator (trade size) raceway required for the number and size of conductors in the cable shall be used.