Quick Hits

📱 EPISODE — Article 337

Type P Cable

SLIDE 1 — What Is a Type P Cable?
🔌 UP TO 2000V, ARMORED OR UNARMORED

Type P cable covers voltages up to 2000V, available in both armored and unarmored designs. This is a specialized, engineering-supervised cable type — not something you'll see on a typical residential or commercial job.

📋 Listing (337.2): the cable itself, PLUS cable ties/straps/hangers, AND connecting fittings — all must be listed and identified.

SLIDE 2 — Uses Permitted & NOT Permitted
✅ USES PERMITTED (337.10)

This cable is narrowly scoped:
1️⃣ Under ENGINEERING SUPERVISION in industrial installations, where maintenance/supervision ensures only QUALIFIED PERSONS monitor and service the system
2️⃣ Hazardous (classified) locations, where other articles specifically permit it

🚫 USES NOT PERMITTED (337.12)
❌ Exposed to physical damage
❌ Anywhere NOT specifically permitted by other articles in the Code

📌 Notice how restrictive this is — no general-purpose use case here. It's engineering-supervised industrial work only.

SLIDE 3 — Bending, Support & Ampacity
📐 BENDING RADIUS (337.24)

No specific numeric formula here — just a general requirement: bending radii during installation AND in-service handling must be ADEQUATE to prevent cable damage. Judgment call based on the cable's construction.

🛠️ SECURING/SUPPORTING (337.30)
Listed cable ties, listed straps/hangers/similar fittings, or other approved means that won't damage the cable.

⚡ SINGLE CONDUCTORS (337.31): installations must comply with 300.22 (typically referenced for hazardous location/plenum-type wiring concerns with single conductors).

📊 AMPACITY (337.80)
🔹 14 AWG and larger → per 310.14(A) or (B)
🔹 18–16 AWG → per Table 402.5 or 310.14(B)
🔹 In cable tray → permitted per 392.80
🔹 Installation can't exceed the temperature ratings of terminations/equipment

SLIDE 4 — Construction Specs + Exam Question
🏗️ CONSTRUCTION SPECIFICATIONS

🔹 Conductors (337.104): TINNED COPPER only, flexible stranding, min. size 18 AWG
🔹 EGC (337.108): multiconductor Type P cable MUST include an EGC complying with 250.122
🔹 Insulation (337.112): thermoset type identified for Type P use, ALL conductors suitable for WET locations, min. wall thickness 0.76mm (30 mils)
🔹 Shield (337.114): metallic shielding permitted over single OR grouped conductors
🔹 Jacket (337.115): multiconductor cables need an overall nonmetallic jacket — moisture-impervious, corrosion-resistant, sunlight-resistant. Single conductors ≥4/0 AWG rated 2000V CAN skip the separate jacket by using increased insulation thickness instead (must still be sunlight resistant)
🔹 Armor (337.116): optional, braided basket-weave design (bronze, tinned copper, stainless steel, or aluminum wire) — armor is NEVER a current-carrying conductor OR an EGC. A nonmetallic jacket per 337.115 still goes OVER the armor

🎉 That wraps up Article 337 — Type P Cable!

🧠 TEST YOURSELF

Q: Per 337.116, can the armor of Type P cable ever be used as an equipment grounding conductor?

A) Yes, always
B) Yes, but only for single-conductor cables
C) No — the armor shall not be used as a current-carrying conductor or as an EGC
D) Only in hazardous locations

(Drop your answer 👇)

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