Code Change Summary: Cables are now included when calculating the number of conductors permitted in a metal wireway.

There are several NEC^® articles that permit installing cables in a raceway. Section 342.2 for example, defines Type IMC conduit as follows:

Intermediate Metal Conduit (IMC). A steel threadable raceway of circular cross section designed for the physical protection and routing of conductors “and cables” and for use as an equipment grounding conductor when installed with its integral or associated coupling and appropriate fittings.

Cables are also permitted in EMT, RMC, FMC, LFMC and LFNC.

In Article 376, a Metal Wireway is defined as follows:

Metal Wireways. Sheet metal troughs with hinged or removable covers for housing and protecting electrical wires “and cable” and in which conductors are laid in place after the raceway has been installed as a complete system.

In the 2017 NEC^®, a proposal was accepted to include cables in Section 376.22 when calculating the fill of a metal wireway. If cables are permitted in various raceways, and part of the definition of a metal wireway in Article 376, it only makes sense that they would also be included when calculating fill for a metal wireway.

Now, when determining gutter or wireway fill, the sum of the cross-sectional areas of all contained conductors “and cables” at any cross section shall not exceed 20 percent of the interior cross-sectional area of the wireway.

A similar change occurred in Article 366 for Auxiliary Gutters.

Below is a preview of Article 376. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC^® edition of NFPA 70.