Free Voltage Drop Calculator Online
Determine electrical voltage drop percentages for single-phase and three-phase circuits based on wire gauge, current, and distance.
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Before installing long branch runs for workshops, hot tubs, or subpanels, calculate voltage drops. Excessive drops can cause motors to overheat, lighting fixtures to flicker, and appliances to run inefficiently.
Frequently Asked Questions (FAQ)
What causes voltage drop?
Voltage drop is caused by the inherent electrical resistance of the wire material. As current flows through the wire over long distances, electrical energy is lost as heat, lowering the voltage arriving at the load.
What is the maximum recommended voltage drop?
The National Electrical Code (NEC) recommends a maximum voltage drop of 3% for branch circuits and 5% for the combined feeder and branch circuits.
How do I decrease voltage drop?
You can decrease voltage drop by increasing the wire gauge size (larger copper/aluminum diameter), lowering the current load, or reducing the run distance.
Why does the phase option factor matter?
Single-phase calculations require a return wire (factor of 2), while balanced three-phase calculations utilize a factor of 1.732 (square root of 3).
Is copper wire less resistive than aluminum?
Yes, copper has higher electrical conductivity than aluminum, leading to less voltage drop for the same wire size.