I. General

installed in wet locations shall be suitable for such locations.

(B) Nonmetallic Auxiliary Gutters. Nonmetallic auxil- iary gutters shall be listed for the maximum ambient temperature of the installation and marked for the installed conductor insulation temperature rating.

(1) Outdoors. Nonmetallic auxiliary gutters shall be per mitted to be installed outdoors where listed and

366.1 Scope. This article covers the use, installation, and construction requirements of metal auxiliary gutters and nonmetallic auxiliary gutters and associated fittings.

366.2 Definitions.

Metallic Auxiliary Gutter. A sheet metal enclosure used to supplement wiring spaces at meter centers, distribution centers, switchboards, and similar points of wiring systems. The enclosure has hinged or removable covers for housing and protecting electrical wires, cable, and busbars. The enclosure is designed for conductors to be laid or set in place after the enclosures have been installed as a complete system.

Nonmetallic Auxiliary Gutter. A flame retardant, non- metallic enclosure used to supplement wiring spaces at meter centers, distribution centers, switchboards, and similar points of wiring systems. The enclosure has hinged or removable covers for housing and protecting electrical wires, cable, and busbars. The enclosure is designed for conductors to be laid or set m place after the enclosures have been installed as a complete system.

366.6 Listing Requirements.

(A) Outdoors. Nonmetallic auxiliary gutters installed out

doors shall comply with the following:

(1) Be listed as suitable for exposure to sunlight

(2) Be listed as suitable for use in wet locations

(3) Be listed for maximum ambient temperature of the installation

(B) Indoors. Nonmetallic auxiliary gutters installed in doors shall be listed for the maximum ambient temperature

of the installation.

II. Installation

366.10 Uses Permitted.

(1) (A) Sheet Metal Auxiliary Gutters. Indoor and Outdoor Use. Sheet metal auxiliary gutters shall be permitted for indoor and outdoor use.

(2) Wet Locations. Sheet metal auxiliary gutters

marked as suitable for the purpose.
FPN: Extreme cold may cause nonmetallic auxiliary gutters to become brittle and therefore more susceptible to damage from physical contact.

(2) Indoors. Nonmetallic auxiliary gutters shall be permitted to be installed indoors.

366.12 Uses Not Permitted. Auxiliary gutters shall not be used under the following conditions:

(1) To enclose switches, overcurrent devices, appliances, or other similar equipment

(2) To extend a greater distance than 9 m (30 ft)

beyond the equipment that it supplements

Exception: As permitted in 620.35 for elevators, an auxiliary gutter shall be permitted to extend a distance greater than 9 m (30 ft) beyond the equipment it supplements.

FPN: For wireways, see Articles 376 and 378. For busways, see Article 368.

366.22 Number of Conductors.

(A) Sheet Metal Auxiliary Gutters. The sum of the cross-sectional areas of all contained conductors at any cross section of a sheet metal auxiliary gutter shall not exceed 20 percent of the interior cross-sectional area of the sheet metal auxiliary gutter. The derating factors in

310.15(B)(2)(a) shall be applied only where the number
of current-carrying conductors, including neutral
conductors classified as current-carrying under the
provisions of 310.15(B)(4), exceeds 30. Conductors for
signaling circuits or controller conductors between a
motor and its