Quick Hits

Episode 2: Circuit Sizing, Maximum Voltage & Overcurrent Protection (694.10 – 694.15)

SLIDE 1 (HOOK / COVER) ⚡ NEC Quick Hit: Wind Circuit Sizing & Overcurrent Protection (Part 2) ⚡ 

Why are wind turbine electric currents legally classified as continuous loads? How do you size conductors and OCPDs? Let's check out Sections 694.10 through 694.15! 👇

SLIDE 2 (MAXIMUM VOLTAGE & CONTINUOUS SIZING)

The 125 Percent Sizing Rule:

• Voltage Limits: One- and two-family dwelling wind output circuits are permitted up to 600 volts. Live parts over 150V to ground must be guarded from unqualified persons.

• Sizing Conductors & OCPDs: Wind electric currents are continuous. Conductors and OCPDs must be sized to carry not less than 125 percent of the calculated maximum turbine/inverter output current.

SLIDE 3 (OVERCURRENT PROTECTION & DC FUSES)

Guarding Against Multi-Source Backfeed:

• Backfeed Protection: Circuits connected to multiple electrical sources must have OCPDs positioned to provide overcurrent protection from all directions.

• DC Fuse Ratings: Fuses and circuit breakers in any DC portion of a wind system must be explicitly listed for DC use with correct voltage and interrupting ratings.

SLIDE 4 (WRAP-UP)

💡 Apprentice Pro-Tip: Some wind turbines use their output circuits to regulate rotor speed, and inverters can operate in reverse during startup. Always verify your backfeed OCPD placement to handle current flowing in both directions!

💬 Save this post for your next wind system electrical calculation! 🔗 

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