425 – Fixed Resistance and Electrode Industrial Process Heating Equipment

425.22(B) – Resistance-Type Heating Elements in Fixed Industrial Process Heating Equipment

Change at a Glance:

Resistance-type heating elements in fixed industrial process heating equipment are now permitted to be subdivided into circuits not exceeding 120 amperes and protected at not more than 150 amperes under certain conditions.

425.22 (Fixed Resistance and Electrode Industrial Process Heating Equipment)

(B) Resistance Elements. Resistance-type heating elements in fixed industrial process heating equipment shall be protected at not more than 60 amperes. Equipment rated more than 48 amperes and employing such elements shall have the heating elements subdivided, and each subdivided load shall not exceed 48 amperes.
Resistance-type heating elements in fixed industrial process heating equipment shall be permitted to be subdivided into circuits not exceeding 120 amperes and protected at not more than 150 amperes where one of the following is met:
(1) Elements are integral with and enclosed within a process heating surface.
(2) Elements are completely contained within an enclosure identified as suitable for this use.
(3) Elements are contained within an ASME-rated and stamped vessel.
Where a subdivided load is less than 48 amperes, the rating of the supplementary overcurrent protective device shall comply with 425.4(B) 425.3(B). A boiler employing resistance-type immersion heating elements contained in an ASME-rated and stamped vessel shall be permitted to comply with 425.72(A).