I have Hampton Bay low voltage 300W Digital Transformer . I like to know if it is adequate for my landscape lighting with the following details:

  • Two wire runs of 12-gauge wire: 1st run is 55 feet long with 5 LED lights with a combined 19 watts. 2run is 148 feet long with 28 LED light with a combined 67.3 watts.

  • I have a 12V tap and a 15V tap on the transformer

  • In total, I have 203 feet of 12-gauge wire, 33 LED lights with 86.3 total combined watts.

Is my 300W transformer sufficient?

If my transformer is sufficient, do I use the 12V tap, the 15V tap, OR Both, with the short run on the 12V tap and the longer run on the 15V tap?

Thank You very much for your assistance.

  • what's a digital transformer?
    – jsotola
    Aug 18, 2023 at 22:58
  • What voltage are the lights?
    – JACK
    Aug 18, 2023 at 23:22
  • @Jack, the voltage shown is 12V. The style of the low voltage lights are MR16, MR11, and G4. Wattage is between 1.1 to 7 per light with most in the 3W range. The light fisxtures are Volt. Aug 18, 2023 at 23:35
  • @jsotola the box states digital but its a 300W transformer Aug 18, 2023 at 23:42
  • @jsotola Apparently it has a digital clock timer built in.
    – Ecnerwal
    Aug 19, 2023 at 2:06

1 Answer 1


As long as a transformer can supply more watts then the load at the correct voltage it will be OK. However it will work fine with tungsten lights without knowing what you have the LED lights may not work, they normally want DC but there are many out there that will work with AC.

You can use an online ohm's law calculator and determine how many amps you will draw, that will let you know if the wire is large enough. I expect you will drop about 0.5V on the longer run and less on the shorter one so 12V should be good for both.

There are also online calculators that will calculate voltage drop across a given length of wire at a given amp load. The voltage drop is up to you. For LEDs I would like to keep it at about 11.5 Volts.

  • Drop for 5.58 A (67.3W @12V) on 128 feet of 12Ga copper is more like 2.88V (of course the real situation is more complicated beacuse the lights are presumably distributed along the 128 feet, not all at the end of it.) The maximum voltage of the LEDs would really matter here.
    – Ecnerwal
    Aug 19, 2023 at 2:12
  • 1.58A to give 19W at 12V on 55 feet of 12 AWG comes out 0.35V drop.
    – Ecnerwal
    Aug 19, 2023 at 2:28

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