Code Change Summary: New code section addressing metal clad type MC cable installed in thermal insulation.

In the 2020 NEC^®, a change was made to address a heat dissipation concern with MC cables installed in contact with thermal insulation without maintaining spacing. The original public input (code change proposal) was accepted for service entrance Type SE cable in contact with thermal insulation but the code panel applied the new code language to type MC and AC cables as well.

Grouped cables can overheat and may sustain damage when installed in thermal insulation and loaded normally. The code panel thought it would be wise to add extra precautions similar for nonmetallic sheathed type NM cables installed in thermal insulation.

The new requirement only applies when ALL three of the following conditions exist:

• Type MC or AC cables are installed in contact with thermal insulation, caulk, or sealing foam, and
• The MC or AC cables contain two or more current-carrying conductors in each cable, and
• Three or more of the cables above are installed without maintaining spacing between cables

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 2020 NEC^® edition of NFPA 70.