Quick Hits

EPISODE 2 — Conductors: Grouping, Mixed Systems & Bending Radius (305.13)

Slide 1 — Hook "Today: the same-circuit grouping rule you know from Article 300 — plus something new, unique to medium-voltage cable: bending radius limits."

Slide 2 — 305.13(A) Same circuit, (B) Different systems

• Same core rule as 300.5: all conductors of the same circuit (grounded conductor, EGCs, bonding conductors included) stay together in the same raceway/cable/trench/etc., with parallel-installation, legacy EGC, and nonferrous-sheath exceptions mirroring Article 300.

• Conductors over 1000V/1500V generally CANNOT share an enclosure/cable/raceway with ≤1000V/1500V conductors — narrow exceptions exist for: ballast primary leads sharing a luminaire/sign enclosure, motor excitation/control/relay/ammeter conductors sharing the motor-circuit enclosure, mixed-voltage conductors inside motors/transformers/switchgear/switchboards/control assemblies, and permanently separated, securely supported conductors in the same manhole.

• Conductors with NONSHIELDED insulation at different voltage levels can never share the same junction/pull box, cable, or raceway — no exceptions for that one.

Slide 3 — 305.13(C) Bending radius — new territory

• Nonshielded conductors: can't be bent to a radius less than 8× the conductor's overall diameter.

• Shielded or lead-covered conductors: minimum bend radius is 12× the overall diameter.

• Multiconductor or multiplexed single-conductor cables with individually shielded conductors: minimum bend radius is 12× the individual shielded conductor's diameter, OR 7× the overall cable diameter — WHICHEVER IS GREATER.

• This matters because bending shielded/insulated medium-voltage cable too tightly can damage the shielding and insulation in ways that aren't visible from outside.

Slide 4 — Quiz + CTA Q: "What's the minimum bending radius for a SHIELDED medium-voltage conductor, relative to its overall diameter?" A) 6 times B) 8 times C) 10 times D) 12 times

✅ Answer: D — 305.13(C): 12 times the overall diameter for shielded or lead-covered conductors.

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