Wiring Landscape Lights

When wiring landscape lights or deciding how to select which type to use, keep in mind that there are many different varieties of landscape or garden lighting available. So I'm going to cover some basics that I hope will get you knowledgeable enough to tackle the Do-It-Yourself landscape lighting installation.

The Different Source Types

Let's go over the major types of outdoor garden lighting and their advantages/disadvantages.

120V Source

The 120v Source lighting (house voltage) is typically used for commercial purposes. The biggest advantage is that this type of source can produce a more powerful light illumination. The disadvantages are numerous. They cost more to operate, they are less safe, harder to install and the list can go on.

12V Source

Or low-voltage lighting is without a doubt the most popular. This type system will cost less to operate, can produce great illumination, allows for an assortment of different style light fixtures and is very easy to install. Electrical knowledge is not required for the do-it-yourself installation.

Solar Powered

Solar powered lighting has come a long way. I for one have tried solar power but I just didn't care much for the amount of illumination they produce. Installation is practically non-existent but keep in mind, it takes a good sunny day for them to really perform well.

So as you can tell, I am going to show you the basics of wiring landscape lights of the low-voltage style.

But before we get to involved. I would like you to watch the following video that briefly covers the information that I will be going over in more detail and it will provide a great visual for the actual installation of low-voltage lighting.

If you Purchased a Kit then you will already have most items necessary for the installation. Most complete kits will provide all the components you'll need. The video should help you on getting started with the installation process. Just be sure to follow the manufacturer's instructions and safety guidelines.

If your designing your own landscape lights then read on and we'll get you started.

When wiring landscape lights, the best place to start is to layout your lighting plan on a piece of paper. This will help tremendously when trying to calculate the number of lights, length of wire and transformer sizing necessary to perform the installation. By designing your own system, you can pick out different styles and types of lighting such as, spot lights on the house and lower intensity lighting for pathways etc. Each type of light draws a different amount of current, so let's go into some simple formulas that will allow for proper operation.

By now you should have sketched a layout of your lighting system which will determine the length of wire, style of lights being used (low voltage variety) and their locations.

Let's go over the basic formulas to determine proper wire size, wire length and transformer sizing.

Voltage Drop

When wiring landscape lights, determining voltage drop is very important so you don't have dim lights at the end of your run. A good rule of thumb is to have no more than 8% voltage drop at the end of your wire run. So let's determine what your voltage drop will be.

By looking at the specifications on your individual lights, you will see how many watts each fixture consumes. Let's total the wattage of all lights in your system.


You have 5 path lights at 8 watts each. That equals 40 watts (5 x 8).
Also there are 2 spot lights at 20 watts each. That equals 40 watts (2 x 20).

Total watts will be 40(path lights)+40(spot lights)=80 watts.

Now that we know the wattage, let's say that your wire length is going to be 80ft. Let's use the following formula to calculate the voltage drop.

Wattage x Footage x .0011 = Voltage Drop.

80(watts) x 80(ft) x .0011 = 7.04%. As I mentioned before, you should keep your voltage drop below 8% so you don't have a dimming effect on the last lights in your wire run. If your voltage drop is over 8%, I would recommend shortening your wire run, removing lights from your run or running two separate systems to allow for the excess wattage and length your wanting to power.


Transformers or power-packs are designed to plug into any 120vac house circuit and reduces the output voltage to 12vac which creates a low-voltage system.

Transformers for your 12v lighting design typically come in sizes of 300, 600, 1000 and 1200 watts. In our example above we calculated that the lights are going to require 80 watts so a 300 watt transformer will be plenty to do the job.

When designing or wiring landscape lights, it is extremely important not to go over the wattage capability of the transformer, plus by having the extra wattage available, will allow you to add more lighting to your system in the future if you desire.

Wire Sizing

Most low-voltage landscape lighting wire comes in two different sizes. 12 and 16 gauge. A good rule of thumb for selecting proper wire size is determining your wattage. Any system under 200 watts will be fine using 16 gauge wire. Over 200 watts, you should use a 12 gauge sized wire.

Final Notes:

Your lighting system or transformer should be plugged into a GFCI circuit breaker for moisture protection. Also, you should always follow the manufacturer's instructions in order to maintain safety and reliability on your purchased products.