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📱 EPISODE 2 — Article 332 (Part 2 of 2)

Securing, Fittings, Ampacity & Construction — Article 332 Complete!

SLIDE 1 — Securing & Supporting (332.30)
🛠️ SUPPORT REQUIREMENTS

MI cable must be supported/secured at intervals not exceeding 6 ft (1.8m) using:
✅ Listed straps, hangers, or similar fittings
✅ Other approved means that won't damage the cable

📌 Fire-rated assemblies often need MORE support than the minimum 6 ft — follow the manufacturer's instructions for the specific fire rating, but never LESS than 6 ft.

Exceptions:
🔹 Horizontal runs through holes/notches per 300.6 → considered supported if within 6 ft intervals
🔹 Fished through concealed spaces where supporting is impracticable → unsupported is OK
🔹 In cable trays → must comply with 392.30(A)

SLIDE 2 — Single Conductors & Fittings
⚡ SINGLE-CONDUCTOR GROUPING (332.31)

Just like MC cable — where single conductors are used, ALL phase conductors (and the neutral, if used) must be GROUPED TOGETHER to minimize induced voltage on the sheath. Ferrous enclosures need extra care too — inductive heating from hysteresis loss is a real concern with single conductors entering steel boxes.

🔧 FITTINGS & TERMINAL SEALS (332.40)

• Fittings connecting MI cable to boxes/cabinets/equipment must be identified for that use

• Terminal seals (332.40(B)): where MI cable terminates, an END SEAL FITTING must be installed IMMEDIATELY after stripping — this keeps moisture out of that highly compressed magnesium oxide insulation. Conductors extending beyond the sheath need individual insulating material too.

SLIDE 3 — Ampacity (332.80)
📊 AMPACITY RULES

Determined per 310.14. Two extra checks:
✅ Conductor temp at the end seal fitting can't exceed that fitting's temperature rating
✅ Installation can't exceed the temperature ratings of terminations/equipment

Special scenarios:
🔹 In cable tray → ampacity per 392.80(A)
🔹 Single conductors grouped (triangular/square, per 332.31) with proper airspace (2.15x the largest conductor diameter) → follow Table 310.17

SLIDE 4 — Construction Specs + Final Exam Question
🏗️ CONSTRUCTION SPECIFICATIONS

🔹 Conductors (332.104): solid copper, nickel, or nickel-coated copper, standard AWG/kcmil sizing
🔹 EGC (332.108): copper sheath = can serve AS the EGC directly; STEEL sheath = a SEPARATE EGC is required
🔹 Insulation (332.112): highly compressed refractory mineral providing proper conductor spacing
🔹 Sheath (332.116): continuous construction for mechanical protection AND moisture seal

🎉 That's a wrap on Article 332 — Mineral-Insulated, Metal-Sheathed Cable, Type MI!

🧠 FINAL EXAM QUESTION FOR ARTICLE 332

Q: Per 332.108, if the outer sheath of Type MI cable is made of STEEL, what is required?

A) Nothing additional — steel sheath always serves as the EGC
B) A separate equipment grounding conductor must be provided
C) The cable cannot be used at all
D) A copper sheath must be added over the steel

(Drop your final answer 👇)

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