Quick Hits

Episode 2: Disconnecting Means & Overcurrent Protection (425.19 – 425.22)

SLIDE 1 (HOOK / COVER)

⚡ NEC Quick Hit: Process Heating Disconnects & OCPDs (Part 2) ⚡

Simultaneous disconnects, the 60-ampere protection rule, and 48-ampere element subdivisions—let's check Sections 425.19 through 425.22! 👇

SLIDE 2 (DISCONNECTING MEANS)

Simultaneous Disconnection:

• Simultaneous Break: Means must be provided to simultaneously disconnect the heater, motor controllers, and supplementary OCPDs from all ungrounded conductors.

• Ampacity & Locking: Disconnects must be rated at not less than 125% of the total load and be lockable open in accordance with Section 110.25.

SLIDE 3 (OVERCURRENT PROTECTION & SUBDIVISION)

Protecting Resistance Elements:

• 60-Ampere Limit: Resistance-type heating elements must be protected at not more than 60 amperes.

• Subdivision Mandate: Equipment rated more than 48 amperes must have its heating elements subdivided so that each subdivided load does not exceed 48 amperes.

• ASME Vessels: Elements contained within ASME-rated and stamped vessels can be subdivided into circuits not exceeding 120 amperes and protected at not more than 150 amperes.

SLIDE 4 (WRAP-UP) 💡 Apprentice Pro-Tip: 

When wiring industrial process heaters over 48 amps, verify that internal supplementary OCPDs properly subdivide the loads into 48-amp segments to limit short-circuit energy and prevent catastrophic element damage!

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← Article 425: Fixed Resistance and Electrode Industrial Process Heating Equipment

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