Voltage drop is created by the internal resistance to the ﬂow of electricity through the cable. It is the diﬀerence between the voltage at the source (the transformer) and that at its end. It is safe to use 12 gauge cable on runs up to 100 feet long carrying up to 100 watt loads, if the ﬁxtures are spaced evenly along the run. For longer runs and larger loads 10 or 8 gauge cable is required. We will be glad to help you calculate the most eﬃcient gauge of cable to use on your project.
Another way to correct for voltage drop is by using the diﬀerent voltage (11v, 12v, 13v, or 14v) taps on the multi tap transformer and as many cable runs as necessary to deliver exact voltage to each location. Use a voltmeter to test voltage at each ﬁxture before waterproofing the splice or connection. Never exceed 12 volts to any ﬁxture!
To manually calculate your voltage drop, please download the excel file below and input your figures into the live interactive workbook directly.
You can use this chart below to estimate your voltage drop without doing any calculations.
For the full guide to outdoor lighting please see this page.