Calculated Industries ElectriCalc Pro User Manual - 38 — E

38 — e

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VOlTaGE DROP

The reduction in Voltage between the power source and the 

load can be determined by entering the Phase, Volts, Amps, 

Wire material, Voltage Drop Wire Size and Length of run. 

The calculator determines Resistance and then the Voltage 

reduction. Voltage Drop can be displayed as Volts dropped, or 

as a percent reduction of potential load.

This calculator also finds Voltage Drop Wire Size once you 

have entered or calculated the Phase, Volts, Amps, Length, 

Wire Type, and allowable VD percentage. It will solve for the 

distance () once you have entered or calculated the 

Phase, Volts, Amps, Wire Type, Voltage Drop Wire Size, and 

allowable VD percentage. The ElectriCalc Pro uses Resistance 

values found in NEC Table 8 Chapter 9 to determine Voltage 

Drop.

Note: Voltage Drop solutions may vary slightly from actual AC circuit 

measurements, as the calculator does not incorporate factors such 

as inductive reactance, skin effect, raceway material, etc. In most 

situations, the DC Voltage Drop calculation method is sufficient to meet 

safety standards for AC systems.

IMPoRTanT noTe on VolTaGe

DRoP CalCulaTIons

The ElectriCalc Pro calculates Voltage Drop and Wire Size using DC 

Resistance as defined by the 2011 NEC. To find the Voltage Drop 

for a specific Wire Size, you must first enter Amps and the one-way 

wire Length (and other required variables), entering the specific Wire 

Size last. Otherwise, for your safety, the calculator will recalculate 

the Wire Sizes based on the NEC Ampacity Tables and maximum 

allowable Voltage Drop.

finding single-Phase Voltage Drop

You are installing 175 Feet of 75°C, #8 THW branch circuit Copper 

conductors to supply an 11A load on a 208V 1Ø system. What is the 

source Voltage Drop at the load?