Voltage Drop Equation For Landscape Lighting

Use this voltage drop equation to figure out how many volts your wire will lose over a distance:

Total watts on low voltage wire * length of wire run in feet / wire size constant listed in chart below = VOLTAGE DROP



(note: the smaller the number the bigger the wire. 8/2 low voltage wire is the largest size)


100 watts of lights at the end of a 200ft wire run on a 10/2 wire

100 * 200 = 20,000 / 11,920 = 1.68 volts

So if you have 12 volts coming out of the transformer the voltage drop equation tells us the voltage will be reduced by 1.68 volts to 10.32 volts.

10.32 volts will produce a slightly yellowish light.

We recommend using a multi-tap transformer so you can increase the voltage to get each landscape light above 10.8 volts.


Multi-tap transformer used with voltage drop equation

Increase voltage on far wire runs with our multi-tap transformers.


Click Here to —-> Learn More About Voltage Drop.

Southwire Voltage Drop Calculator —-> Southwire has a great voltage drop equation calculator and even a mobile app for iPad, iPhone & Android devices. We do not stock Southwire low voltage cable we stock and sell Colman Cable low voltage wire. If you are interested in Southwire products we can order them.

Cast Lighting Voltage drop Calculator —-> Cast lighting provides the most in depth tools for landscape lighting professionals. We sell Cast Lighting but the products are not loaded on our website. If you are interested in any of their landscape lighting products please contact us for a quote.