Estimate the voltage drop over a length of wire.
Voltage drop grows with the round-trip wire length and current. Comparing it to the system voltage as a percentage shows whether it stays within a typical three percent limit. Excessive voltage drop wastes energy and can starve equipment, so it must be checked on long or high-current runs.
Wiring Voltage Drop
Voltage drop = 2 x length x current x resistance / 1000
Voltage drop = 2 x length x current x resistance / 1000 Voltage drop grows with the round-trip wire length and current. Comparing it to the system voltage as a percentage shows whether it stays within a typical three percent limit.
Excessive voltage drop wastes energy and can starve equipment, so it must be checked on long or high-current runs.
This calculator takes 4 inputs: One-way length, Current, System voltage, Resistance per 1000 ft. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.