Last updated: 2022-07-25

Design - Install

Table of Contents

Start a Sketch

Create a drawing accurate enough to allow detail for a complete materials and component list.
image of landscape light design sketch

Determine Light Requirements
  • Accent lighting (Create new features with light)
  • Mood lighting
  • Light dark areas
  • Security

Example Lighting Job

Materials List

Path Lights – 7 total
Spot Light
Well Light – 4 total
Light fixtures with 7 watt LED MR16
11 fixtures; 11 x 7watts = 77 watts
Transformer - 200 watt suggested, room for expansion
Landscape Light Wire (cable) - 100 feet used
image of landscape light design sketch

Voltage drop calculations with 12 volt and 77 watts

#14 Wire - 4.03 volts drop farthest from transformer. Most modern transformers come with center tap feature where 15 volts DC is available to use. Voltage drop will still occur over the length of wire where fixtures at the far end farthest away from the transformer see a 4 volt drop down to 11 volts.
#12 Wire - 2.54 volts drop farthest from transformer. Here voltage drop at the farthest location from the transformer is only 2.5 volts. Improved performance with lights closer to same brightness.
#10 Wire - 1.6 volts drop.

A good strategy is to use #10 or #12 off the transformer as far as you can go with it, and use #14 or #16 to groups of fixtures. Smaller wire at fixture is easier to connect. Most fixtures use #18 - #22 AWG wire size.

Plan What And Where Lights Be Placed

Walk around and decide what you want to illuminate. Illuminate is a nice word, visualise a tree uplit, or a wall wash of soft light etc.
Path lights can illuminate a trail, and also serve to mark an entrance or just a low to ground feature.
Identify areas you will bring light into, and layout some wire without burial, just place some fixtures around, test bthe results.
This way you can make changes, tweak the final look before a more finished install. Although changes are easy to make later on.

Transformer Location

  • The transformer requires a 120 volt AC receptacle.
  • In areas where winter snow piles up, the transformer should be mounted high enough to stay out of the piles. Melting snow is concern.
  • Photo cell needs clear view of night and day. Photo cell should not be facing lights that turn on enough where the photo cell thinks it is day light out again. You can get a revolving door effect.A lot of transformers come with a photo cell with about a 60 inch reach wire. This makes placement easier. Garages, sheds anywhere there is power. Choose a location as close as possible to the areas to be lighted. Just because an a transformer is rated for outdoor use, doesn't mean it has to go out side. Mounting inside a garage and drilling a hole for the landscape light wire is good option.
The best placement for the transformer is as close as possible to the fixture locations. Sometimes it makes sense to use more than one transformer - especially when fixtures are situated throughout a large property. If multiple transformers are used then create a separate plan for each one. Mark transformer locations on your sketch.

- Choose Transformer Size

To determine the transformer size you will need, add up the wattages of all lamps you plan to use. And add at least 25% to 50% for voltage drop and planning ahead.
Transformer size is based on power output. Power output is measured in watts.
Transformers are not the large heavy things they used to be. Low power consumption LED lights allow for smaller, lighter weight transformers. Todays electronics and packaging provide easy to use features for lighting control.

Calculate expected power consumption

Add together the wattage of your individual lights
Multiply that total by 1.5
The new total is a safe transformer size, in watts. Any upgrades aside. Add future lights! Plan Ahead? Yes.
Many time it is more convenient to add a second transformer.

You can plug most low-voltage transformers into a GFI outlet. Save on cable by finding an outlet closest to your lighting needs.

Features to look for in transformer selection.

The transformer below is typical of modern low voltage power supply's (transformer with features).
A useful feature is the remote photo cell. The photo cell is attached to a 60 inch wire which makes it easier to place for better sensing light/dark.

Set Fixture Locations

Before you install any fixtures in the property, mark their approximate positions in the landscape using small flags or pencils. Indicate the positions on your sketch and mark what fixture types will go at each location. As you walk the property, make rough measurements to indicate the distances between fixtures and the transformer, and between the fixtures themselves.

- Landscape Lights

LED lights use less energy, allowing you to run your system on a smaller, less costly transformer
LED's last longer than other bulb types, and generate little to no heat. As mentioned above; LED bulbs using 5 to 7 times less power than halogen, and provide equal or better light out put.

A little light can go a long way outdoors. Create layers by using a combination of path lights, up lights and flood lights.

Up Lighting.

With LED light, a little goes a long way.

image for light in kelvins

Determine Wire Runs

Lay Landscape Wire Out Before Burial

Place fixtures hook them up and test before moving on to permanent placement.

Not all locations require wire burial.

We recommend simply running cables along the ground and tucking them behind plantings or covering them lightly with dirt or mulch. Most light fixtures include stakes so you can simply insert them in the ground.
Planter maintenance may be easier if you can see where the wire is.
To protect wire in planters where you really need it buried, but know digging and weed control may binjur wire in future, use low cost PVC conduit. Cheap mand save bookoo time in the long run.
Tip: PVC pipe is also a great way to creat a riser for lites that come with stakes. there are times a taller stake will come in handy.

Wire Burial Across Lawns And High Traffic Areas

Across lawns Take a flat bladed spade and create a 4 inch to 6 inch deep slit and push the wire down in.

Boring under borders and side walks is common.

For a sidewalk, dig an 18 inch deep hole on each side of the walk. At the bottom of each hole start an underground trench towards the other side. It is easier than it sounds.

Wire to Light Fixture Groups


There are many wiring methods available. You don't want to run a single wire from each fixture to the transformer - 20 fixtures, 20 wires all ending at the transformer - that would waste a lot of wire. Instead, we minimize the total amount of wire by using one of the following wiring methods
scetch for planning and install landscape lighting wire layout

Landscape Lighting Wiring Methods

  • Section your light areas.
  • Each section should stem off the the main supply wire.
  • Each section will have lights wired in parallel.

Layout TIPS for Optimal Installation and Results:

Lower loads per run means lower voltage drop. This is not much of a concern for LED systems since voltage drop for most systems is minimal. But if your system is large (more than 15 fixtures or about 100W) break up your layout into multiple cable runs of ~ 100-150 watts per run. If you have more than 150 watts in an area -- break it up into 2 runs. For LEDs, lower wattages mean you can group more fixtures onto single runs, but keep in mind that it still makes sense to use one home run wire for each zone; this is more energy efficient and makes for easier troubleshooting.

Break your layout into Distance Zones. For example, put fixtures 15-30 ft away from the transformer on one run; fixtures 25-40 ft on another run; fixtures 30-50 ft on another run; and so on. The goal is to have all the fixtures on a run be roughly the same distance from the transformer so they have similar amounts of voltage drop.

Lights Wired In Parallel Share Equal Voltage


landscape lighting wire must be in parallel

To Wire Lights In Series Is Wrong

How to Wire Lights In Parallel

Wire Size

Voltage Drop and Wiring Size

Voltage drop not the issue it used to be when using LED for light source.
The wire size used can affect system performance.
Power loss occurs from watts used by lights, some loss is from wire resistance. Power loss on the wire; Voltage drops as wattage increases.
image showing voltage drop on wire with load

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-gauge. 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 - Max Wattage
#18 GA - 120 W
#16 GA - 156 W
#14 GA - 180 W
#12 GA - 240 W
#10 GA - 300 W
#8 GA - 480 W

Sample Job Quote

Before LED is as reliable as they are today. Now days the transformer size will be adequate at 200 watt with plenty extra room... Job quote example with photo of completed job logo for landscape light page

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