AC Voltage DropCalculator
Professional AC calculator with NEC Table 9 values, power factor, and conduit types.
AC Circuit Parameters
NEC Table 9 Reference
Calculation Results
Excellent - Meets NEC recommendations for feeders
AC Voltage Drop Formula
Where Z (effective impedance):
Z = R×cos(φ) + XL×sin(φ)
NEC Chapter 9
AC impedance values are from NEC Chapter 9 Table 9, accounting for reactance effects in conduit types.
- •Steel conduit increases AC resistance due to magnetic effects
- •PVC/Aluminum conduit has no magnetic effect
- •Reactance becomes significant in larger conductors
Power Factor Guide
- Resistive loads (heating): 1.0:1.0
- Motors: 0.80-0.90:0.80-0.90
- Motors (starting):0.20-0.40
- LED lighting: 0.90-0.98:0.90-0.95
- Fluorescent lighting: 0.90-0.95:0.85-0.95
Related Resources
AC Voltage Drop Calculation Explained
AC vs DC Calculations
AC voltage drop calculations are more complex than DC because conductors exhibit both resistance and reactance (inductive impedance) when carrying alternating current. The effective impedance depends on the power factor of the load and the physical arrangement of the conductors.
Steel (magnetic) conduit increases the effective AC resistance compared to non-magnetic conduit like PVC or aluminum, particularly for larger conductors. This is due to eddy current losses in the conduit material.
Three-Phase Considerations
Three-phase systems use the √3 (1.732) multiplier instead of 2 used in single-phase calculations. This accounts for the phase relationships between conductors in a balanced three-phase system.
For unbalanced three-phase loads, calculations become more complex and may require analysis of each phase individually. This calculator assumes balanced loading conditions.