Quick Hits

Episode 4: Capacity, Sizing & Power Circuit Rules (710.15)

SLIDE 1 (HOOK / COVER) ⚡ NEC Quick Hit: Stand-Alone Capacity & Circuit Math (Part 4) ⚡

How do you size an off-grid system when there's no utility grid to absorb peak loads? Section 710.15 governs source capacity and circuit calculations for stand-alone systems. Let's finish Article 710! 👇

SLIDE 2 (CAPACITY & RATING) Sizing to Supply Connected Loads:

• Adequate Rating: A stand-alone system must have adequate capacity and rating to supply all equipment intended to be operated at one time.

• User Selection: The user is permitted to select which loads are connected to the system (either manually or via energy management/load shedding automation).

SLIDE 3 (POWER PRODUCTION CIRCUIT SIZING) Applying Section 705.28 Rules:

• Circuit Math: Under Section 710.15(B), power production source output circuits must comply with Section 705.28.

• The 125% Rule: Conductors and overcurrent protective devices (OCPDs) must be sized to carry not less than 125% of the maximum continuous current produced by the power source.

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

Because off-grid inverters and generators have finite peak power ratings, improper load calculations will cause the source to trip offline under surge conditions. Always account for motor starting currents and continuous load factors!

💬 Save this post for your final code review on off-grid power systems! 🔗

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