Dwelling Load Calc: Standard vs Optional Method (Worked)
5:24
Same house, two completely different, both legal, ways to calculate its service size.
In this lesson: the same 2,500 sq ft house run through both the standard method (Part III of Article 220 — demand factors applied piece by piece) and the optional method (220.82 — sum everything first, then one demand factor). 125A vs 100A, side by side, plus the 220.82(A) eligibility rules, the 220.83 method for additions, and the common mistake of using the optional method on a multi-unit building.
Based on the 2023 NEC (Article 220).
