Quick Hits

PART IV — SERVICE-ENTRANCE CONDUCTORS

EPISODE 6 — One Set Per Service, Insulation and Sizing over 1kva (268.40, 268.41, 268.42)

Slide 1 — Hook "New Part! Service-ENTRANCE conductors — the segment between the service point and the actual disconnecting means. Starting with the 'one set per service' rule and its exceptions."

Slide 2 — 268.40 Number of sets

• General rule: each service drop/overhead set/underground set/service lateral supplies only ONE set of service-entrance conductors.

• Exception No. 1: multi-occupancy buildings can get one set per occupancy/group — with plaque/directory requirements scaling up once you exceed 6 disconnect locations for a given service type.

• Exception No. 2: 2 to 6 disconnects in separate enclosures, grouped at one location, fed from a single service source, can share one set of service-entrance conductors.

• Exception No. 3: one set can supply the specific supply-side-connected systems covered in 268.82(3)/(4) (things like standby power, fire pump, or renewable energy systems).

Slide 3 — 268.41 & 268.42

• 268.41 Insulation: service-entrance conductors entering/on the exterior of a building must be insulated for the applied voltage — with the same narrow bare-conductor exceptions as underground conductors (bare copper in raceway, approved direct burial, or part of a listed cable assembly).

• 268.42 Sizing: same transformer-only / transformer+utilization / supervised-installation logic again — PLUS a hard floor of 6 AWG (or 8 AWG if multiconductor cable), and the grounded conductor can't be smaller than what 250.122 requires for an EGC.

Slide 4 — Quiz + CTA Q: "What's the general minimum size for service-entrance conductors (not multiconductor cable)?" A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG

✅ Answer: B — 268.42: not smaller than 6 AWG (8 AWG floor specifically for multiconductor cable).

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