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Episode 4: Electrode-Type Boilers & Mandatory Markings (425.80 – 425.86)
Episode 4: Electrode-Type Boilers & Mandatory Markings (425.80 – 425.86)
SLIDE 1 (HOOK / COVER)
⚡ NEC Quick Hit: Electrode Boilers & Safety Markings (Part 4) ⚡
Electrode boiler branch circuits, pressure vessel grounding, and mandatory warning labels—let's finish Article 425! 👇
SLIDE 2 (ELECTRODE-TYPE PROCESS BOILERS)
Generating Heat via Liquid Conduction:
Scope: Applies to boilers operating at 600 volts or less where heat is generated by current passing between electrodes through the liquid being heated.
Branch-Circuit Sizing: Conductors and OCPDs must be calculated on the basis of 125 percent of the total load (motors excluded).
SLIDE 3 (GROUNDING & MANDATORY WARNING LABELS)
Isolation and Safety Warnings:
Vessel Grounding: If fault currents do not pass through the pressure vessel and it is electrically isolated from electrodes, all exposed metal parts and piping must connect to the EGC. Otherwise, the pressure vessel must be isolated and insulated from ground.
Mandatory Nameplate: Boilers must be marked "Electrode-Type Process Heating Boiler".
Service Warning: Must include the permanent warning marking: "All Power Supplies Shall Be Disconnected Before Servicing, Including Servicing the Pressure Vessel".
SLIDE 4 (WRAP-UP) 💡 Apprentice Pro-Tip:
When servicing electrode boilers, never rely on a single disconnect—ensure all power supplies to the pressure vessel are locked out per the mandatory warning label before opening the system!
💬 Save this post for your final code review on Industrial Process Heating Equipment!
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⚠️ Educational NoticeQuick Hits are educational explanations based on my understanding of the NEC. Always verify requirements in the current adopted NEC, applicable local amendments, manufacturer instructions, and with the AHJ.
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