How to Determine Voltage Drop

Voltage drop is determined by multiplying the total watts on the system by the total length of cable/conductor, and dividing by the cable/conductor constant. (These cable constants are listed below)

• Total Watts - Sum of wattage for every lamp on one run.
• Cable/Conductor Length - Length of cable/conductor used (in feet) from the transformer to the fixture for which you are calculating voltage drop.
• Cable/Conductor Constant - Indicates thickness of the cable/conductor. The thicker the cable/conductor, the lower the conduction resistance and the lower the voltage drop.

To calculate voltage drop using the Ambiance® Lighting System's low voltage cable/conductor, use the following formula:

Cable/Conductor Constant (x) Total Consumed Wattage Load on Run (x) Length of Run
= Voltage Drop %

Remember - Voltage drop is per run, not per transformer!!

To achieve optimum lighting effects using the Ambiance® Lighting System, do not allow the voltage drop to be greater than 8% (75% light output). Halogen lamps' light output and lamp life are severely affected when operated with voltage over 12.5 volts and with a voltage drop greater than 10%.

Incandescent lamps (which include Xenon lamps) may be operated with any voltage drop. However, higher voltage drop will result in lowered light output and color of light becoming yellow. In some applications up to 18% voltage drop (50% light output) may be acceptable where the level of illumination is not objectionable. The lower voltage will extend the non-halogen light bulb life. For example, a 10% drop in voltage will extend the non-halogen's light bulb life approximately four times, while reducing the illumination level by 30%.

To achieve even illumination on an Ambiance® Landscape Lighting system at points where two different lighting segments meet, do not allow for more than 5% voltage drop at the ends. A differential over 5 % will have a noticeable change in light.