Quick Hits

Article 371 (Part 1 of 2)
Flexible Bus Systems — New in 2023!

SLIDE 1 — Scope, Listing & Reconditioned Equipment (371.1, 371.2, 371.3)
🆕 WHAT IS A FLEXIBLE BUS SYSTEM?
Created in the 2023 NEC cycle to recognize flexible bus systems as their own wiring method — must be listed AND designed/specified by a qualified engineer for the specific site application.
✅ Must be LISTED (371.2)
🚫 Reconditioned flexible bus systems are NOT permitted to be installed (371.3(B))

SLIDE 2 — Uses Permitted (371.10)
✅ WHERE YOU CAN USE THEM
1️⃣ Services, feeders, and branch circuits
2️⃣ Indoors
3️⃣ Outdoors — if identified for outdoor use
4️⃣ Corrosive, wet, or damp locations — if identified for use
5️⃣ Exposed
6️⃣ Behind access panels
7️⃣ Penetrating walls and floors (per 371.18)
8️⃣ Air-handling spaces — if listed for air-handling spaces

SLIDE 3 — Uses Not Permitted & Installation Design (371.12, 371.14)
⛔ WHERE YOU CAN'T USE THEM
1️⃣ Hoistways
2️⃣ Locations exposed to severe physical damage
3️⃣ Hazardous (classified) locations — unless Chapter 5 specifically permits it
📐 DESIGN REQUIREMENT (371.14)
Must be designed and specified for the specific installation site by a qualified engineer, within listing limits and manufacturer's instructions — ALL documentation must be available to the AHJ.

SLIDE 4 — Overcurrent Protection (371.17) + Final Exam Question
⚡ OCPD RATING BY APPLICATION
🔹 Services → per 230.90
🔹 Feeders → per 215.5 (240.4 permitted as exception)
🔹 Branch circuits → per 210.20 (240.4 permitted as exception)
🔹 Transformer secondary → per 240.21(C)
🔹 Generator terminals → generator OCPD per 445.12 permitted if sized per 445.13
🔹 Battery terminals → per 240.21(H)
🔹 Size reductions → OCPD required at the reduction point — EXCEPT in industrial establishments, where it can be omitted if the reduced-size run is ≤50 ft, rated at least ⅓ of the upstream OCPD, and free from contact with combustible material.

🧠 FINAL EXAM QUESTION FOR ARTICLE 371 (Part 1)
Q: Per 371.14, who must design and specify a flexible bus system for a specific installation site?
A) The installing electrician
B) A qualified engineer
C) The manufacturer's sales rep
D) The AHJ
(Drop your final answer 👇)

Article 371 Part 1 = DONE ✅ Part 2 drops next — grounding, terminations, supports & marking! ⚡ #JoshTheSparky #NEC2026 #ElectricianLife

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