Quick Hits

📱 EPISODE 6 — Article 245 (FINAL PART)

Feeders & Branch Circuits — Article 245 Complete!

SLIDE 1 — Feeder/Branch-Circuit Protection Basics (245.26)
🔌 WHERE PROTECTION GOES

Feeder and branch-circuit conductors need OCP in EACH ungrounded conductor, located where the conductor receives its supply — OR at an alternative location IF it's engineered with proper fault studies and time-current coordination analysis.

Two ways to provide that protection:
1️⃣ Overcurrent relays + current transformers — 3-phase circuits need breakers with a MINIMUM of three overcurrent relay elements from three CTs (can be combined into one electronic relay unit)
2️⃣ Fuses — one fuse connected in series with each ungrounded conductor

SLIDE 2 — Relay Configuration Nuances
🧩 SPECIAL RELAY ALLOWANCES (245.26(A)(1))

On 3-phase, 3-wire circuits:
✅ A residual-circuit relay element CAN replace one of the phase relay elements
✅ A relay element operated from a CT linking ALL phases can replace BOTH the residual element AND one phase CT

If the neutral isn't regrounded on the load side (per 270.27(B)), that all-phase CT can also link the grounded conductor (neutral) too.

📊 Protective devices must detect AND interrupt every current value that could occur in excess of their trip-setting or melting point (245.26(B)). And per 245.26(C), device timing + available fault current + conductor size must all be coordinated to prevent dangerous conductor temperatures during a short circuit.

SLIDE 3 — Feeder Sizing & Taps (245.27)
📏 OCPD SIZING FOR FEEDERS

🔹 Fuse continuous ampere rating: cannot exceed 3x the conductor ampacity
🔹 Breaker long-time trip element (or electronically-actuated fuse min. trip setting): cannot exceed 6x the conductor ampacity
🔹 Fire pump conductors get their own allowance under 695.5(B)(2)

🔀 FEEDER TAPS (245.27(B))
Tap conductors can be protected by the FEEDER's OCPD — as long as that same OCPD also protects the tap conductor itself. Simple as that.

🎉 That's Article 245 — Overcurrent Protection for Systems Over 1000V — complete, start to finish!

SLIDE 4 — Exam Question + CTA
🧠 FINAL EXAM QUESTION FOR ARTICLE 245

Q: Per 245.27(A), the continuous ampere rating of a fuse protecting a feeder shall not exceed what multiple of the conductor's ampacity?

A) 1x
B) 2x
C) 3x
D) 6x

(Drop your final answer below 👇)

Article 245 = DONE ✅ FOLLOW for more daily quick-hit NEC study notes — next up we head into Article 250: Grounding and Bonding ⚡ #JoshTheSparky #NEC2026 #ElectricianLife

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