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📱 EPISODE 3 — Article 368 (Part 3 of 3)

Part IV — Busways Over 1000V AC/1500V DC — Article 368 Complete!

SLIDE 1 — Structural & Barrier Requirements
🔥 ADJACENT STRUCTURES & FIRE BARRIERS

368.214: metal-enclosed busways installed so temperature rise from induced circulating currents in adjacent ferrous parts won't hazard personnel or create a fire hazard.

368.234:
🔹 Vapor seals required at building walls where runs go indoor-to-outdoor (Exception: forced-cooled bus)
🔹 Fire barriers required at fire wall/floor/ceiling penetrations

SLIDE 2 — Drainage, Ventilation & Terminations
💧 DRAIN FACILITIES (368.236): drain plugs/filter drains required at low points to remove condensed moisture.

🌬️ VENTILATED ENCLOSURES (368.237): follow Article 110 Part III and 495.24.

🔌 TERMINATIONS (368.238): seal-off bushings/baffles required where bus enclosures terminate at machines cooled by flammable gas. ALL termination/connection hardware must be ACCESSIBLE.

SLIDE 3 — Switches, Wiring & Expansion
🔀 SWITCHES (368.239)

Switching devices/disconnecting links need the SAME momentary rating as the busway. Non-load-break switches must be interlocked to prevent under-load operation; disconnecting link enclosures interlocked against energized-part access.

🔌 SECONDARY WIRING (368.240): secondary control devices/wiring insulated by fire-retardant barriers from primary circuit elements (except short instrument transformer leads).

🌡️ EXPANSION (368.244): flexible/expansion connections required in long straight runs, or where crossing building vibration insulation joints.

SLIDE 4 — Neutral, Grounding & Marking + Final Exam Question
⚡ NEUTRAL CONDUCTOR (368.258)

Neutral bus (where required) sized to carry ALL neutral load current, including harmonics, with adequate momentary/short-circuit rating.

🌎 GROUNDING (368.260): metal-enclosed busway SHALL be grounded — mandatory, not conditional, at this voltage class.

🏷️ MARKING (368.320): each run needs a permanent nameplate with rated voltage, continuous current (both forced-cooled AND self-cooled ratings if applicable), frequency, impulse withstand voltage, 60-Hz withstand voltage, momentary current, and manufacturer name.

🎉 That's a wrap on Article 368 — Busways!

🧠 FINAL EXAM QUESTION FOR ARTICLE 368

Q: Per 368.260, is grounding of metal-enclosed busway (over 1000V) mandatory or conditional?

A) Conditional — only in wet locations
B) Mandatory — metal-enclosed busway SHALL be grounded
C) Optional based on manufacturer recommendation
D) Only required if voltage exceeds 15,000V

(Drop your final answer 👇)

Article 368 = DONE ✅

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