Basic Voltage Drop Calculator

When voltage at the beginning of a length of cable (at the transformer) is higher than the voltage at the end, the difference is known as "voltage drop".  The visual indicator of voltage drop is dim light fixtures at the end of a cable run.   The closer the light fixtures are to the transformer, the higher the voltage and brightness.  Voltage drop can be minimized through proper selection of the cable size based on total wattage load and the length of run.  This "wizard" will help you determine the proper wire size and transformer to maximize light output with minimum voltage drop while protecting the bulbs from premature burnout.

Input Total Watts and Length of Wire for each zone in the table below...

Cable 1 2 3 4 5 6 7 8 9 Total Recommended
Total Watts *
Length of Wire  
Wire Size
Volt Tap
Total Wire Needed:

8 GA.

10 GA.

12. GA