Code Change Summary: New requirements added for cable tray installations.

In the 2023 NEC^®, language was added in Article 690 to provide additional details for single-conductor PV wire smaller than 1/0 AWG installed in cable trays.

Section 690.31(C)(2) has allowed the use of PV or distributed generation (DG) cable in cable trays for PV installations but until this code change, there really hasn’t been any direction given on adjustment factors or the layering of these smaller conductors in the cable tray.

Article 392 provides additional information but not for cables smaller than 1/0 AWG.

In the 2023 NEC^®, the language in 690.31(C)(2) was expanded with the following additional code language that requires a careful read:

Where installed in uncovered cable trays, ampacity of single-conductor PV wire smaller than 1/0 AWG, the adjustment factors for 1/0 AWG single conductor cable in 392.80(A)(2) shall be permitted to be used.

Where single-conductor PV wire smaller than 1/0 AWG is installed in ladder or ventilated trough cable trays, the following shall apply:

(1) All single conductors shall be installed in a single layer.

(2) Conductors that are bound together to comprise each circuit pair shall be permitted to be installed in other than a single layer.

(3) The sum of diameters of all single conductor cables shall not exceed the cable tray width.

The final language for the code change omitted the word “or” but the public input behind the new language specifically addressed “ladder or ventilated trough cable trays”. Wire mesh cable trays are often used in rooftop PV cable installations, and it is likely that this new code language will be expanded to include other cable tray types not currently mentioned in the 2023 code language.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2023 NEC^® edition of NFPA 70.