Voltage Drop Calculation Method

Three-Phase % Voltage Drop = Calculated Current in Amps * Effective Z * (Feeder Length / 1,000) * 100 / Line-to-Neutral Voltage

Single-Phase % Voltage Drop = Calculated Current in Amps * Effective Z * (Feeder Length / 1,000) * 100 * 2 / Line-to-Neutral Voltage

Calculated Current in Amps is based upon the total calculated current in kVA assuming a balanced load.

Effective Z = R cos(theta) + X sin (theta) (NEC Table 9 Note 2)

R = Resistance set in the Wire Sizing command.

X = Reactance set in the Wire Sizing command.

theta = 0.85 power factor

Line-to-Neutral Voltage is used based upon NEC Table 9 Note 2: "Multiplying current by effective impedance gives a good approximation for line-to-neutral voltage drop."


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