Code Change Summary: Many changes occurred for electric space heating cables in Part V of Article 424.

Many of the 2017 changes in Part V of Article 424 were the result of the Article 424 Electric Space Heating Working Group.  This group was formed as an outcome of an industry Standards Technical Panel (STP) meeting for Electric Radiant Heating Panels and Cables (which covers UL Standards for these products). Some of the changes are as follows:

424.38 Area Restrictions. Previous language stated that they are not permitted to extend beyond the room where they originate. In the 2017 NEC^®, it is the opposite. Advances in product designs and standards make it unnecessary to restrict heating cables to the room in which they originate, especially for floor heating applications. Sometimes there may be a path leading from one room to another in which the floor can be warmed with the same heating cable circuit without creating safety issues as long as the NEC^® and manufacturer’s installation instructions are followed.

424.38(B) Uses Not Permitted. Items 4, 6 and 7 were added and several revisions were made including clearing up the rules on ceiling installed heating cables. Previous code language did not allow heating cables over walls. New language clarifies that heating cables cannot be installed over the top of walls where the wall intersects the ceiling.

424.39 Clearance from Other Objects and Openings. Revisions were made to make it clear that the section applies to ceiling installed heating cables.

424.41 Ceiling Installation of Heating Cables on Dry Board, in Plaster, and on Concrete. The title of the section was restructured to make it clear that the section applies to most types of ceiling installations rather than just concrete ceilings.

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 2017 NEC^® edition of NFPA 70.

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