Code Change Summary: New code section on heating cables installed in walls.

The NEC^® has addressed the installation of space heating cables under floor coverings for many code cycles in Part V of Article 424.

In the 2023 NEC^®, new Section 424.48 was added to provide requirements for space heating cables and cable sets installed in walls with a future effective date of January 1, 2026.

Starting January 1, 2026, new code Section 424.48 will permit heating cables and cable sets to be in, on, or behind walls if the installation is not prohibited by Section 424.38(B), and the following five conditions are met:

(1) The heating cables and cable sets must be identified as suitable for installation in, on, or behind walls.

(2) The heating cables and cable sets must be GFCI protected.

(3) A grounding means, such as copper braid, metal sheath, or other approved means, must be provided.

(4) The heating cables and cable sets must be AFCI protected.

(5) The heating cables and cable sets must be installed no higher than 4 feet above the floor.

Keep in mind that the GFCI protection required in rule 2 above is not triggered by the proximity of the cables to a water source such as a sink.

Additionally, the AFCI protection required in rule 4 above is not voltage specific, nor is it based on the occupancy classification of the building or the type of room the cables are installed in. Most other AFCI protection requirements in the NEC^® apply only to 120-volt, single-phase, 10-, 15-, and 20-ampere branch circuits supplying outlets or devices in specific rooms or areas of dwelling type occupancies.

Being required to install the heating cables no higher than 4 feet above the floor as mentioned in rule 5 above is intended to reduce the chance that the cables will be damaged by fasteners when mirrors or pictures are hung on the wall.

Similar requirements for heating panels in walls were added in new Section 424.93(C).

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.