Voltage Drop Calculator


What is Voltage Drop?

  • Voltage Drop is a decrease in the voltage created by internal resistance to the flow of electricity through the wire.
  • It is the difference between the voltage supplied at the beginning of a wire run (at the transformer) and that at the end of the wire run.
  • If the Voltage Drop is too big, you will be able to see a decrease in brightness of the light fixtures as they get further away from the transformer.


Instructions for filling out the form:
  1. 1. Enter a wattage number.
  2. 2. Select a wire gauge.
  3. 3. Press calculate.

Voltage Tap Setting (V) 12131415
Maximum Cable Length (ft) 372.60510.60648.60786.60
The WAC Lighting Voltage Drop Calculator Gauge Wire Diagram

This calculator is based on 120VAC in and 12VAC out and is for use as a guide only to help you begin your lighting project. We strongly recommend checking the actual voltage at each fixture with a volt meter before burying and finalizing your project.

We accept no responsibility for the use of the information provided.