Enter one-way length
For single-phase and DC circuits, the formula doubles it for the outgoing and return conductors. Three-phase uses √3.
20 years Navy Seabee Construction Electrician First Class (SCW)
Practical electrical tools and explanations shaped by 20 years of active-duty electrical work, technical instruction, and civilian facility assessment. Start with a voltage-drop estimate you can actually inspect.
Tool 01 / Voltage drop
Estimate conductor voltage drop with the circular-mil method. Enter one-way distance; the calculator handles the return path or three-phase factor.
Read the result
Voltage drop is one decision in a complete installation. Use this number to test the run, then verify the rest of the system.
For single-phase and DC circuits, the formula doubles it for the outgoing and return conductors. Three-phase uses √3.
A low percentage does not prove adequate ampacity. Check insulation rating, terminals, ambient temperature, bundling, and the governing code.
Design current and starting behavior matter. Motors, long feeders, and sensitive equipment may call for a tighter target or a fuller impedance calculation.
On the bench
Conductor selection with transparent assumptions for insulation, terminals, ambient temperature, and conductor count.
Next toolA fast layout check that keeps trade sizes, conductor counts, and allowable fill easy to audit.
PlannedCount conductors, clamps, devices, and grounding conductors without losing the thread halfway through.
Planned