**Low Voltage Cable Length**

In planning a low voltage system, it is necessary to consider the impact of voltage drop. Because of cable’s inherent resistance, voltage drops along its length: the end-of-run lamps will be dimmer than those at the beginning. Since voltage drop is a function of cable length and cable size and total fixture wattage, voltage drop can be minimized in several different ways.

- Use multiple cable runs
- Use heavier gauge cable (8 or 10 gauge)
- Shorten cable lengths or runs
- Reduce VA of individual fixtures
- Reduce the total number of fixtures on a run
- Use multiple transformers in different locations.

Cable is measured by gauge. The lower the number, the thicker the cable and more current it carries. Common cable size for low voltage lighting is available in three gauges: #12-2, #10-2, and #8-2. To calculate maximum cable length, use the formula below.

Vd = Voltage drop in the section of cable, in volts

L = Length of the section of the cable (one way distance), in feet

VA = Total VA values carried by the section of cable for the fixtures it supplies

Kc = Cable Constant as follow:

Please refer to WAC Lighting website for voltage drop calculator.

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