Power Cable Calculator
The purpose of this calculator is to help you determine which wire and voltage to use on a low voltage lighting system for optimum performance.
Step #1 - Input the voltage of your existing or new power transformer:11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24 volts
Step #2 - Input the total length of your wire from the transformer to each branch circuit
Step #3 - Plug in the total wattage of your individual branch circuits
Step #4 - Select a drop multiplier: 1, 1.5 or 2
You choose: 0 Voltage, 0 Feet, and Wattage, with a 1 drop multiplier.
Minimum Cable Constant = 0
18 gauge wire is acceptable.
Always start your calculations with 12-gauge wire. The voltage at a fixture is the actual voltage supplied (12 Volts) minus the voltage drop. The voltage supplied may be increased by use of a multi-tap transformer. These multi-taps have alternate voltage sources to counteract a long cable run with too high of a voltage drop. Another way to counteract a high voltage drop is change to a thicker wire, such as 10-guage. If you need more voltage drop than you are getting, you may change to a thinner wire, such as 14-gauge, but a thinner wire supports less wattage.
Here is a chart to determine the maximum wattage allowed for each buried wire.
| Gauge | #18 GA | #16 GA | #14 GA | #12 GA | #10 GA | #8 GA |
| Max Wattage | 120 W | 156 W | 180 W | 240 W | 300 W | 480 W |
