Calculations 15 min
Voltage Drop Calculation Formulas Explained
Basic Voltage Drop Formulas
Voltage drop calculations are based on fundamental electrical principles. The formulas differ depending on whether you're working with single-phase or three-phase systems, and whether the circuit is AC or DC.
Single-Phase AC/DC Formula
Vd = 2 × I × L × R / 1000
- Vd = Voltage drop (volts)
- I = Current (amperes)
- L = One-way length (feet)
- R = Resistance (ohms per 1000 feet)
Three-Phase AC Formula
Vd = √3 × I × L × R / 1000
Uses √3 (1.732) instead of 2 for three-phase systems.
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