Quick Hits

Episode 1: Scope, Systems & Data/Power Transmission (725.1 – 725.2)

SLIDE 1 (HOOK / COVER) ⚡ NEC Quick Hit: Class 2 & 3 Power-Limited Circuits (Part 1 - Scope & Basics) ⚡ 

Security systems, access control, nurse call stations, and low-voltage dimming controls—welcome to Article 725! Let's break down the scope and listing rules for Class 2 and Class 3 circuits. 👇

SLIDE 2 (SCOPE & WHAT'S INCLUDED) What Systems Fall Under Article 725?

• Low-Voltage Control: Covers power-limited remote-control, signaling, and data circuits not integral to utilization equipment.

• Excluded Zones: Does not cover IT rooms under NFPA 75 (which fall under Article 645) or low-voltage wiring tightly bundled inside interconnected IT equipment.

SLIDE 3 (POWER & DATA TRANSMISSION LISTING) Combining Power and Data (PoE & Hybrid Circuits):

• Power sources providing power and data over Class 2 cables must be listed under approved standards (like UL 62368-1).

• Paralleling Ban: Outputs from these power sources shall not be paralleled or interconnected unless explicitly listed for such use.

SLIDE 4 (WRAP-UP) 💡 Apprentice Pro-Tip: 

Remember that Class 2 and Class 3 circuits are characterized by low energy levels that differentiate them from electric light and power circuits—meaning alternative rules apply to wire sizing, overcurrent protection, and separation from line-voltage conductors!

💬 Save this post for your next low-voltage rough-in or exam prep! 🔗 

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