Master electrical calculations with our comprehensive guide to voltage drop, wire sizing, and NEC compliance for professional electrical installations.
This guide is for educational purposes. Always consult with licensed electrical professionals and verify compliance with local electrical codes before implementing any electrical work.
Voltage drop is the reduction in voltage that occurs as electrical current flows through a conductor due to the conductor's resistance. This phenomenon is fundamental to electrical engineering and must be carefully calculated to ensure proper system operation.
VD = 2 × ρ × I × L / A
Where: VD = Voltage Drop, ρ = Resistivity, I = Current, L = Length, A = Cross-sectional Area
VD = √3 × ρ × I × L / A
Three-phase systems use √3 (1.732) multiplier due to phase relationships
| System Type | Feeder Limit | Branch Circuit Limit | Total Limit |
|---|---|---|---|
| Single-Phase | 3% | 3% | 5% |
| Three-Phase | 3% | 3% | 5% |
These are NEC recommended limits, not requirements. Some applications may require tighter voltage drop limits for proper operation. Always check equipment specifications.