Quick Hits

EPISODE 4 — Conductor Sizing and Identification MV Cable (315.12, 315.14)

Slide 1 — Hook "Today: the smallest wire allowed at each voltage tier, and how ungrounded conductors get identified at medium voltage."

Slide 2 — 315.12 Conductors

• Minimum conductor sizes scale UP as voltage climbs — Table 315.12(A): 2001V-5000V needs at least 8 AWG; 5001V-8000V needs 6 AWG; 8001V-15,000V needs 2 AWG; 15,001V-28,000V needs 1 AWG; 28,001V-35,000V needs 1/0 AWG. Higher voltage generally demands a physically larger minimum conductor.

• Material: aluminum, copper-clad aluminum, or copper, unless otherwise specified.

• Stranding: conductors installed in raceways must be stranded unless specifically permitted/required to be solid elsewhere (same exception logic as low-voltage — busbars are a common exception).

Slide 3 — 315.14 Conductor identification

• Ungrounded conductors (single or in multiconductor cables) must be finished to be CLEARLY distinguishable from grounded and grounding conductors — and that distinguishing marking can't conflict with the surface markings required elsewhere in this article.

• Branch-circuit ungrounded conductors follow 210.5(C); feeders follow 215.12.

Slide 4 — Quiz + CTA Q: "What's the minimum conductor size required for medium-voltage cable rated 8001V-15,000V?" A) 6 AWG B) 2 AWG C) 1 AWG D) 1/0 AWG

✅ Answer: B — Table 315.12(A): 2 AWG minimum for that voltage tier.

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