Quick Hits

Episode 3: Power Sources, 72-Hour Duration & Transfer Gear (708.20 – 708.30)

SLIDE 1 (HOOK / COVER) ⚡ NEC Quick Hit: COPS Power Sources & 72-Hour Run Times (Part 3) ⚡

How long must a critical operations power system run during an outage? Article 708 steps up the runtime and reliability requirements compared to standard standby systems. Let's break it down! 👇

SLIDE 2 (THE 72-HOUR RUN TIME & FUEL RULES) Sizing and On-Site Supply:

• The 72-Hour Rule: Unlike standard standby (2 hours), COPS alternate power sources must be capable of operating the system for a minimum of 72 hours at full load (Section 708.22).

• On-Site Fuel & Pumps: Internal combustion engines require secured on-site fuel supplies, and fuel transfer pumps must be powered directly by the COPS.

• Dual Connections: Must include provisions to connect a portable or vehicle-mounted generator.

SLIDE 3 (TRANSFER EQUIPMENT & ISOLATION) Automatic Transfer Switches (ATS):

• Transfer equipment must be automatic, listed for emergency use, electrically operated, and mechanically held.

• Bypass and Isolation: If loads are supplied by a single feeder, the COPS must include bypass-isolation features to allow servicing of the ATS without dropping power to critical loads.

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

Under Section 708.20(C), all COPS power sources must be grounded as separately derived sources (with specific exceptions) to ensure maximum electrical isolation and reliability.

💬 Save this post for your next emergency generator specification! 🔗

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