Quick Hits

EPISODE 10 — Buildings Supplied by a Feeder or Branch Circuit and Generators (270.32, 270.34, 270.35)

Slide 1 — Hook "What happens when a separate building on the same property gets its power from a feeder — plus generator grounding rules."

Slide 2 — 270.32 Buildings/structures fed by a feeder or branch circuit

• The supplied building needs its own grounding electrode system and grounding electrode conductor.

• Grounded systems: an EGC runs WITH the supply conductors to the building disconnect and grounding electrode(s) — the grounded conductor can NOT be tied to the EGC or grounding electrode at that building (with a narrow legacy exception for pre-existing installations).

• Ungrounded systems: same idea — an EGC runs with the supply conductors, connected to both the disconnect and the grounding electrode(s).

Slide 3 — 270.34 & 270.35 Generators

• 270.34 Portable generators: frame doesn't need its own grounding electrode IF it only supplies equipment mounted on/plugged into itself, and the frame is bonded to those receptacles' EGC terminals. Same logic (plus frame-to-vehicle bonding) applies to vehicle/trailer-mounted generators.

• 270.35 Permanently installed generators: need a conductor providing an effective ground-fault current path run to the first disconnect. If it's a separately derived system, follow 270.30. If overcurrent protection isn't built into the generator, install a sized supply-side bonding jumper between the generator's EGC terminal and the disconnect's EGC terminal.

Slide 4 — Quiz + CTA Q: "A portable generator only powers equipment mounted on/plugged into itself. Does its frame need a separate grounding electrode?" A) Yes, always B) No, under the specific conditions in 270.34(A) C) Only if rated over 5kW D) Only for construction sites

✅ Answer: B — 270.34(A): no separate grounding electrode needed when those specific conditions are met.

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