Quick Hits

EPISODE 1 — Scope, Permitted Wiring Methods & Temperature Limits (305.1, 305.12)

Slide 1 — Hook "New article! Article 305 is Article 300's medium/high-voltage twin — the foundational wiring-methods rules for systems over 1000V AC / 1500V DC." Text overlay: ARTICLE 305 — GENERAL WIRING REQUIREMENTS OVER 1000V ⚡ Part 1 of 14

Slide 2 — 305.1 Scope

• Covers wiring methods/materials for systems rated over 1000V AC / 1500V DC.

• Doesn't apply to conductors that are an integral part of equipment (motors, controllers, MCCs, factory-assembled control gear, listed utilization equipment) — same carve-out you saw in Article 300.

Slide 3 — 305.12 Limitations — what wiring methods are even allowed

• Table 305.12(A) lists what's permitted at this voltage class: pull/junction boxes, conduit bodies, handhole enclosures, Type MC cable (when also identified Type MV), Type MV cable/joints/terminations, Type P cable, IMC, NUCC, HDPE, RMC, PVC, RTRC, EMT, auxiliary gutters, busway, cablebus, cable trays, messenger-supported wiring, outdoor overhead conductors, insulated bus pipe (IBP), LFMC, and FMC — each with its own permitted voltage range.

• Exposed runs of Type MV cable, bare conductors, and bare busbars (copper or aluminum) ARE allowed, but only in locations accessible to QUALIFIED persons only. A narrow exception covers airfield lighting cable in restricted airport lighting vaults.

• Temperature: no conductor can be used in a way that exceeds its insulation's rated operating temperature — governed by 315.60.

Slide 4 — Quiz + CTA Q: "Exposed runs of bare Type MV cable, bare conductors, or bare busbars are permitted only in locations accessible to whom?" A) The general public B) Qualified persons only C) Building management D) Licensed contractors only, regardless of training

✅ Answer: B — 305.12(A): qualified-persons-only access is required for exposed bare/MV cable runs.

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