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📱 EPISODE 3 — Article 330 (Part 3 of 3)

Ampacity & Construction Specifications — Article 330 Complete!

SLIDE 1 — Ampacity Basics (330.80)
📊 HOW TO DETERMINE AMPACITY

🔹 14 AWG and larger → per 310.14 or 315.60
🔹 18 AWG and 16 AWG → per Table 402.5
🔹 Installation can't exceed the temperature rating of terminations/equipment

Special scenarios:
✅ In cable tray → ampacity per 392.80
✅ Single conductors grouped (triangular/square config) with proper airspace (2.15x the largest conductor's diameter) → follow Table 310.20 (≤2000V) or Table 315.60(C) (>2000V)
✅ More than 2 MC cables in contact with thermal insulation/caulk/sealing foam without spacing → ampacity adjustment per Table 310.15(C)(1)

SLIDE 2 — Conductor & EGC Specs (330.104, 330.108)
🔩 MINIMUM CONDUCTOR SIZES

Power conductors (ungrounded/grounded/EGC):
🔹 16 AWG copper, nickel, or nickel-coated copper
🔹 14 AWG copper-clad aluminum
🔹 12 AWG aluminum

Control/signal conductors:
🔹 18 AWG copper/nickel/nickel-coated copper
🔹 16 AWG copper-clad aluminum
🔹 12 AWG aluminum

🌎 EGC RULE (330.108): if MC cable is used to provide the EGC, it must comply with 250.118(A)(10) and 250.122. If the sheath construction isn't recognized as an EGC on its own, an insulated or uninsulated wire-type EGC must be integral to the cable.

SLIDE 3 — Insulation & Sheath Construction (330.112, 330.116)
🧵 INSULATION RULES

1000V or less: 18/16 AWG control/signal conductors need a type listed in Table 402.13 (min. 90°C rating); 16 AWG and larger power conductors need a type listed in Table 310.4(1) or identified for MC use.
Over 1000V: insulated conductors per Table 310.4(2) and Table 315.10(A).

🛡️ SHEATH TYPES (330.116)
Metallic covering must be smooth sheath, corrugated sheath, OR interlocking metal tape armor — continuous and close-fitting. Single-conductor MC needs a NONMAGNETIC sheath/armor. The sheath is NEVER permitted as a current-carrying conductor.

SLIDE 4 — MC-HL for Hazardous Locations + Exam Question
⚠️ MC-HL REQUIREMENTS (330.126)

Where marked MC-HL, the cable must be listed with:
✅ A gas/vapor tight CONTINUOUS CORRUGATED metallic sheath
✅ An overall jacket of suitable polymeric material
✅ A SEPARATE equipment grounding conductor

🎉 That's a wrap on Article 330 — Type MC Cable, complete!

🧠 FINAL EXAM QUESTION FOR ARTICLE 330

Q: Per 330.126, what type of sheath is required for cable marked MC-HL for use in hazardous locations?

A) Smooth metallic sheath only
B) Gas/vapor tight continuous corrugated metallic sheath
C) Interlocking metal tape armor only
D) No sheath is required if the jacket is polymeric

(Drop your final answer 👇)

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