Electrical Load Sizing Methodology
GridShieldPower.com calculates emergency power sizing using standardized engineering formulas compliant with the National Electrical Code (NFPA 70 / NEC 2026) and IEEE Standard 446.
1. Motor Starting Surge (Locked Rotor Amps - LRA)
Induction motors (found in refrigerators, well pumps, air conditioners, and sump pumps) require 3x to 6x continuous running current during the first 100 to 300 milliseconds of rotor rotation.
2. Conductor Ampacity & 3% Voltage Drop Rule
In compliance with NEC 210.19(A) Informational Note No. 4, generator feeder cords exceeding 50 feet are sized to restrict total voltage drop to under 3% at maximum rated continuous amperage:
3. Fuel Consumption & Derating Coefficients
Engine output derates by 3.5% for every 1,000 feet of altitude above sea level and 1% for every 10°F above 77°F ambient temperature. Natural gas fuel sources apply an automatic 15% to 20% energy density derating compared to 87-octane gasoline.