Article 425. Fixed Resistance and Electrode Industrial Process Heating Equipment.
Code Change Summary: A new Article was added.
In the 2017 NEC®, a new article was added to address fixed resistance and electrode industrial process heating equipment. The intent was to bring requirements for commercial and industrial process heating equipment into the NEC® in their own article, which in turn provides clarity and improves usability of the NEC® for those installing and inspecting these types of systems.
Before the new article, industrial boilers, duct heaters, strip heating, immersion heating, process air heaters and the like were not specifically covered in the NEC®.
The language in the new article might look familiar. Some of it was taken directly from Articles 424 and 422. The new Article provides rules on equipment listing, working space, sizing circuits, overcurrent protection, marking, disconnection and the like.
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.
2017 Code Language:
N ARTICLE 425
Fixed Resistance and Electrode Industrial Process Heating Equipment
425.1 Scope. This article covers fixed industrial process heating employing electric resistance or electrode heating technology. For the purpose of this article, heating equipment shall include boilers, electrode boilers, duct heaters, strip heaters, immersion heaters, process air heaters, or other approved fixed electric equipment used for industrial process heating. This article shall not apply to heating and room air conditioning for personnel spaces covered by Article 424, fixed heating equipment for pipelines and vessels covered by Article 427, induction and dielectric heating equipment covered by Article 665, and industrial furnaces incorporating silicon carbide, molybdenum, or graphite process heating elements.