Choosing the Correct Cable/Wire for your Lighting System

Cable/Wire is most often taken for granted when it comes to landscape lighting systems. It is very easy to overlook such an essential component in the design. "Let’s just get the cheaper cable” is not the recommended attitude when creating you projects. Cable can make or break your system. It can create landscape lighting nightmares and cause headaches & confusion. Let’s avoid that by choosing the right cable/wire from the get-go!!!

The selection of proper size cables will help ensure that you have enough voltage available at each lamp to achieve the desired effect. The cable used in professionally installed low voltage lighting systems range from 18 Gauge to 8 Gauge. In the American Wire Gauge system, as the numbers become smaller, the cable gets bigger (i.e. 8G > 12G). These cables have a parallel construction of two or three wires. 12G/2 means that the cable has two wires, side-by-side, with the copper being the 12 Gauge.

There are two major factors to consider when choosing the correct cable for your system: distance and wattage.

Distance: the distance between the transformer and the first lamp, and the distance between each lamp thereafter.
Wattage: the total watts consumed on the cable run. When considering watts consumed, always calculate the highest wattage lamp that will be used in the fixtures.
12/2: twelve-gauge two-conductor wires. (max 20 amps) (max 240 watts) @ 12-volts.
10/2: twelve-gauge two-conductor wires. (max 30 amps) (max 360 watts) @ 12-volts.
8/2: twelve-gauge two-conductor wires. (max 40 amps) (max 480 watts) @ 12-volts.

Wiring Methods

The "Daisy Chain” Method

We strongly recommend that you Do Not Use the straight run method. This type of structure feeds most of the voltage to the first lamp of the system which leaves less voltage for the remaining lamps resulting in less and less as the system continues.






The "T” Method

This method is the most widely used and highly recommended. We feel that this method works the best. It is a more balanced system providing balanced voltage to all the fixtures in your design.




Things to keep in mind when using the "T” method:

1. It is always best to keep your cable run 25’ from the "T” connection or an overall distance of no more than 50’.

2. Remember your maximum watts per cable run:

a. Max 192 watts per run on 12-gauge cable.
b. Max 288 watts per run on 10-guage cable
c. Max 384 watts per run on 8-guage cable

3. Stay within 3 to 5 fixtures per run depending on the wattage of each lamp used.

4. Always use the proper tap on the transformer and proper cable size for your main feed in order to deliver a desired 12 volts to the "T” connection.

Voltage Drop

Voltage Drop can be defined as the difference in electrical potential between two points in a circuit. The first place a voltage drop occurs is in the transformer where 120 volts turns into 12. Long cable runs, cable connections, and light fixtures are other causes as well. But what affects you the most when installing a system is the long cable runs. Remember that voltage is like pressure. The longer the run, the less pressure you will have at the end.

View the Voltage Drop Reference Chart


Have fun, be safe and be creative with your new lighting system!! Enjoy!