Residential Service Panel Upgrade: 100A to 200A/400A Conversion, NEC 2023 Load Calculations
Reviewed by Residential Construction & Building Code Editorial Board
Modernizing electrical infrastructure: Article 220 general lighting and appliance demand factors, 4/0 aluminum SE cable, meter base upgrades, and whole-home surge protection.
With EV chargers (Level 2 48A), induction cooktops, and heat pumps replacing gas appliances, 100-amp service panels are frequently overloaded. Upgrading to 200A or 400A service requires strict adherence to NEC Article 220.
1. NEC 220.82 Optional Residential Load Calculation
Load Category
Standard Calculation Method
Demand Factor Applied
General Lighting & Small Appliances
3 VA per sq. ft. + (2) 1,500 VA small appliance + (1) 1,500 VA laundry
First 10,000 VA at 100%; Remainder at 40%
Electric Heating vs. Air Conditioning
Nameplate rating of largest load (Heating vs AC)
100% of the larger load
Dedicated Fast EV Charger (48A)
48A x 240V = 11,520 VA continuous load
125% continuous duty (14,400 VA)
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Residential Construction & Building Code Editorial Board
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