Charger kW ampacity calculation
Three-phase AC input current, a 125% continuous-load allowance, and a preliminary standard OCPD rating.
Three-phase charger example
125% current = (AC input kW × 1,000 × 1.25) ÷ (√3 × V × power factor)
At 62.5 kW AC input, 480 V, and power factor 1:
(62,500 × 1.25) ÷ (480 × √3) = 93.97 A
Approximately 94 A at 125%, with 100 A as the preliminary standard OCPD. This assumes AC input power, not a 62.5 kW DC output rating.
√3 ≈ 1.732. Check manufacturer input ratings, required protection, and the adopted code before using this estimate for an installation.
Enter your values and select Calculate to see a step-by-step result.
Balanced three-phase estimate. Use the manufacturer’s maximum input current and specified circuit requirements for final sizing. DC output kW must not be entered as AC input kW: conversion losses and auxiliary loads can increase input demand. The preliminary OCPD is only the next standard size at or above the unrounded 125% result; it does not verify equipment maximum OCPD, conductor protection, terminal ratings, derating, interrupting rating, load management, or service capacity. No wire size is selected.