Quick Hits

Episode 2: Reactance Ratings, Overload Protection & Conductor Sizing (445.11(B) – 445.13)

SLIDE 1 (HOOK / COVER)

⚡ NEC Quick Hit: Generator Ratings & Conductors (Part 2) ⚡

Alternator reactance markings for units over 15 kW, constant-voltage overload protection, and minimum conductor ampacity rules—let's check Sections 445.11(B) through 445.13! 👇

SLIDE 2 (REACTANCE MARKINGS & OVERLOAD PROTECTION)

Sizing and Reactance Data:

• Reactance Markings (>15 kW): Portable generators larger than 15 kW and stationary generators must be marked with subtransient, transient, synchronous, and zero-sequence reactances (or available fault current for inverter-based designs).

• Constant-Voltage Overload Protection: Constant-voltage generators must be protected from overload by inherent design, circuit breakers, fuses, protective relays, or other identified overcurrent protection means.

SLIDE 3 (CONDUCTOR AMPACITY & TAPS)

Carrying the Generator Output:

• Minimum Ampacity (No OCPD Provided): Conductors from generator terminals to the first distribution device must have an ampacity of not less than 115 percent of the generator's nameplate current rating (or 100 percent if the design and operation prevent overloading).

• Tapped Conductors: Where the generator is equipped with a listed OCPD, conductors are permitted to be tapped from the load side in accordance with Section 240.21(B).

SLIDE 4 (WRAP-UP)

💡 Apprentice Pro-Tip: Remember that uncoordinated generator conductors feeding your first distribution panel require a 115% ampacity multiplier unless the generator's internal design explicitly prevents overloading!

💬 Save this post for your next generator feeder layout!

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