How Voltage Drop Worksheets Work
Length × current × resistance, without pretending to be an electrical engineer’s stamp
Free Calculator Hub Editorial Team
6 min read
How Voltage Drop Worksheets Work
Voltage-drop worksheets exist to make conductor resistance visible. They will not replace a load calculation stamped for a permit, but they do teach why long extension-cord style runs starve tools of voltage.
The arithmetic
For DC or single-phase, VD ≈ (2 · L · I · RΩ/kft) / 1000. Three-phase uses √3 instead of 2. Percent drop is 100 · VD / Vsource.
Choosing a wire next
If drop is high, move to the wire-size worksheet to search for a larger AWG that still meets a simplified ampacity check. Then read the caveats guide before touching building wiring.