Quick Hits

EPISODE 9 — Separately Derived Systems Pt 2 Ungrounded Systems and Outdoor Sources (270.30(B), (C))

Slide 1 — Hook "Part 2 of separately derived systems — what changes when the system is UNGROUNDED, plus the outdoor-source rule."

Slide 2 — 270.30(B) Ungrounded separately derived systems

• Still needs a grounding electrode conductor (sized per 270.66) connecting the system's metal enclosures to a grounding electrode — this connection point can be anywhere from the source to the first disconnect.

• Still needs a grounding electrode, same rules as the grounded version (270.30(A)(4)) — except portable/vehicle-mounted generators get a break per 270.34.

• Still needs a supply-side bonding jumper from source to first disconnect.

Slide 3 — 270.30(C) Outdoor source

• If the separately derived system's SOURCE is located OUTSIDE the building/structure it supplies, the grounding electrode connection has to be made right there at the source location.

• From there, everything else in 270.30(A) [grounded] or 270.30(B) [ungrounded] still applies as normal.

Slide 4 — Quiz + CTA Q: "If a separately derived system's source is located outdoors, where must the grounding electrode connection be made?" A) Only inside the building it supplies B) At the source location itself C) At the nearest utility pole D) It's not required for outdoor sources

✅ Answer: B — 270.30(C): the connection is made at the outdoor source location.

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