Quick Hits

Episode 8 — Selective Coordination, Orderly Shutdown, and GFPE

Covers: 240.11, 240.12, 240.13

Hook: How do you make sure only the breaker closest to a fault trips — not the whole building? That's selective coordination.

Slide 2: Where the code elsewhere requires a feeder OCPD to selectively coordinate with a service OCPD, every feeder OCPD fed directly by that service device has to coordinate too — meaning only the device nearest the fault should open, keeping everything else running. Where an orderly shutdown matters more than instant automatic tripping (certain industrial processes), coordinated short-circuit protection paired with overload monitoring/alarming is permitted instead of automatic overload opening.

Slide 3: Ground-fault protection of equipment gets extended here too — 240.13 requires GFPE per 230.95 for any building/structure main disconnect (not just the service) rated 1000A+ on a solidly grounded wye system over 150V to ground (up to 1000V) or a solidly grounded DC system over 150V to ground (up to 1500V DC) — with the same carve-outs for continuous industrial processes, systems already protected elsewhere, and fire pumps.

Quiz: What minimum disconnect rating triggers the GFPE requirement under 240.13?
Answer: 1000 amperes or more.

CTA: Follow — ungrounded conductor protection and interrupting ratings are next.

← View Chapter 2 Home

← Back To Article 240 Home

← Back To Quick Hits Home