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How to: Wire Low Voltage Landscape Lighting

Let's do our best to keep everything here as non-technical as we can. You will want to be familiar with landscape lighting wiring terminology.

Step 1: Create your lighting design; decide what you want to highlight.
Step 2: You need to know how many fixtures (and where) you plan to install (refer to your design).
Step 3: Decide the wattage for each fixture and total that to determine transformer size:
  • Example - 20 fixtures x 20 watts = 400 watts. Typically transformers come in 150, 300, 600, 900, 1200 and 1500 watts (some brands come in odd increments as well). For this example, you'd want to use at least 600 which leaves room for higher watts as plants grow or to add on to your system at a later date.
  • Some transformers require you use only 80% capacity (600 watt can only wire up to 480) while others are fully loadable (use up to 600 watts)
  • If you have  a large area to cover (like front yard and back yard), consider adding one transformer to the front and one to the back. This will keep wiring simple and make expanding your system much easier in the future.
Simple so far...right? Now you know what you want, where you want it and what you need to power it, it is time to get going with the labor and the fancy wiring. For a small system, lets say up to 20 lights in either your front or back yard, these tips will work out fine. If you are installing more than 10 or 20 lights in one area, you may want to consult with a licensed low voltage (C-7) specialist or an electrician versed in voltage drop.

Step 4: Select your wire gauge
  • 12-2 Low voltage landscape lighting, direct burial wire is most common for lighting systems
  • If you are required to run wire further than 150 feet from transformer, you will want to consider using a heavier gauge wire (10-2 is the next from 12-2).
  • The maximum watts you will want to have on one line of 12-2 wire is 190 watts. That number works within 75 feet (furthest fixture from transformer). When you exceed 75 ft, the maximum wattage will decrease to 185 watts  (@ 100 ft and 145 watts @ 150 ft. 
  • For our example of 20 lights at 20 watts (400 watts total), we would have at least three (3) lines running back to the transformer , with wattage spread as even as possible. Two lines would not be enough (200 watts per line would exceed the maximum of 190 watts per line).
  • 10-2 gauge wire will allow you to wire up to 290 watts per line. That numbers works within 75 feet; drops to 280 at 100ft and 220 watts at 150ft. When you reach 200 ft you drop to 165 watt and so on. You'll see the benefit in using the 10 gauge but you will also notice the cost; you'll have to do the math. For our 20 light example, 12-2 would be cost effective and the wire is easily found in local hardware stores at reasonable prices. For bigger jobs and longer runs 10 gauge will save you time and money.
Step 5: If I haven't lost you, you'll  want to decide now which fixtures will be wired together and which wiring method you will use.

Using our example of 20 fixtures at 20 watts (400 watts), the daisy chain method and 12-2 wire, the wiring diagram would look like this:
  • Line 1 - 80 watts
  • Line 2 - 80 watts
  • Line 3 - 80 watts
  • Line 4 - 80 watts
  • Line 5 - 80 watts
Five lines with 80 watts each will equal 400 watts. With the daisy chain method you want to limit each line to four fixtures. This method requires more wire and lines however; you will have less voltage drop. You will need a volt meter when you are ready to connect to the transformer. The meter will help you determine which "tap" to connect to. See our tips on transformers for more information.

Keep in mind, this is the most simple wiring method; other methods used by a professional will include the T-Method and the Hub system. These methods are a bit more technical and if you are up to the challenge, I would encourage you to check them out.

***Good news for the energy conscious; when using LED lights, the daisy chain works perfectly. If our example where  twenty (20) LED lights we'd need just one line using 12-2 wire. The 20 watt lights could be replaced with three (3) watt LED for a similar light output. 20 x 3 = 60 watts!