Voltage Drop Recommendation Study

Voltage drop is calculated as a screening check using conductor DC resistance with temperature correction per conductor material. This page does not model full AC impedance or power-factor reactance effects:

VD% = (√3 × I × R × L) / V × 100   [3-phase]
VD% = (2 × I × R × L) / V × 100   [single-phase]

where I = load current (A), R = conductor resistance per unit length (Ω/m at operating temperature), L = one-way length (m), and V = nominal line voltage (V).

NEC recommendations (informational notes):

• NEC 215.2(A)(3): Feeder circuits — ≤ 3 % recommended
• NEC 210.19(A)(1): Branch circuits — ≤ 3 % recommended
• Combined feeder + branch — ≤ 5 % recommended

Cables without length, load current, voltage, or conductor-size data are marked Not Evaluated but remain listed in the table. Circuit type (feeder/branch) is determined from the Circuit Type or Service Type field in the cable schedule.