Outdoor Lighting / Landscape Lighting Installation Tutorial
There are two types of landscape lighting fixtures, line voltage and low voltage landscape lighting. Line voltage lighting is 120V, which is the regular voltage inside our home that we use for all in home appliances. Installing line voltage landscape light fixtures will require an electric junction box to be installed at where the fixture is and the wires preferrably be contained inside conduits so that it is not exposed to the elements. More work is involved when installing a line voltage lighting system, and it is less flexible, as we cannot freely move the line-voltage light fixtures. A line-voltage landscape lighting system is also considered less safe than a low-voltage system. A low voltage lighting system operates at 12V instead of 120V. Having low voltage fixtures is recommended because they are more energy efficient compared to line-voltage incandescent light fixtures and the low-voltage nature of the system poses virtually no risk of safety hazard out on the landscape. Therefore by having low voltage lighting outside is preferred since it’s safer, easier to install, and allows more flexibility.
In order to install a low voltage lighting system, an extra component is necessary, the transformer. A landscape lighting transformer typically converts the voltage from 120V (or 277V in some cases) to 12V. In this tutorial, we will focus on the various aspects of installing a low-voltage landscape lighting system.
With general electric and lighting knowledge a low voltage lighting system is fairly easy to install. Even though there is no need of intricate wiring a basic knowledge of the system and its aspects are needed for a proper installation of outdoor lighting fixtures. The basic terms needed to install a set of path lights or other landscape lighting fixtures are the transformer, power source, hub, cables, voltmeter and the fixtures. Below we will explain what these are.
Transformer
A transformer is a device that increases or decreases the electricity voltage and current that is being distributed. Each transformer has its capacity yet this capacity cannot be reached or the life of the transformer will decrease dramatically along with the life of the fixtures. Common transformers and their capacities are 300W, 600W, 1000W, and 1200W. This is needed when setting up outdoor lighting because they are usually 12V instead of the standard 120V thus we are decreaseing from 120V to 12V.
One must also calculate how much wattage that is going to be used, then buy the corresponding transformer.
Number of fixtures X watts per bulb
And example is you want to set up 10 fixtures that are 20W per bulb.
12 x 20 = 240
A 300W transformer is ideal for this set up.
Something to keep in mind when purchasing the transformer is the rule of thumb for is not to exceed 90% load. Again we want to emphasis that we do not want to maximize the capacity of the transformer because its life will decrease and the fixtures will not light properly.
Power Source
Can be a hard-wired or a socket from the house. The power source is 120V; the transformer will convert it to 12V.
Hub
The hub is an ideal component to join multiple connections (light fixtures) to the transformer when there are more than 30 ~ 40 fixtures, for the sake of easier installation. In the case of a landscape lighting system using less than 30 light fixtures, the hub is optional; the lights can be connected directly to the transformer.
Voltage Drop
Voltage drop occurs when electricity goes through a long distance. Naturally the electricity gradually drops the further it has to go. This is visible when the furthest lights are dimmer compared to the ones closest to the transformer.
How to calculate voltage drop
Total watts: sum of all wattage on one home run
Cable Length: from transformer to last fixture in feet
Cable Constant: indicates the thickness of copper wire
(Total watts x cable length) / cable constant = voltage drop
| Wire Size | Constant |
| #12/2 | 7500 |
| #10/2 | 11920 |
| #8/2 | 18960 |
An example: the transformer is putting out 12V and we have 72W using a 12/2 cable, with 25 feet in length, it will be:
(72W x 125ft) / 7500 = 1.2
Then we take 12V – 1.2V and the Voltage Drop at 125ft away from the transformer is 10.8V.
Cable
Voltage drop is a problem that can easily be solved with proper cables and by using multi-tap transformers or even changing the design of your layout. Recommended cable is 12,10,or 8 gauge direct burial low voltage. Heavier cables can reduce this combined with shorter cable runs. Make sure cable is suitable for wet locations.
Voltmeter
A device that measures voltage, this is necessary since voltage must be measured during installation to ensure the correct amount of voltage is being used.
Those are some of the common components needed when installing low voltage lighting systems. Now we will go through the steps for a proper installation.
- Locate your power source, it is recommended that you use a regular socket of your house, one in the garage is preferred but an outlet outside of the house can be used also. The transformer needs to be mounted one foot above the ground.
- Locate the areas you want lit and sketch them out.
- Lay out fixtures in the pattern designed, removing foliage near by. Install mounting devices leaving 1 inch above the ground.
- Wire the fixtures to transformer or hub; there are different ways to do this. Quick connectors help make this process go faster. The other way is “cut-and splice†this refers to cutting the wire but it can take a long time and for a person not skilled in this manner might result in improper installation. When connecting the wires to the hub or transformer use water-tight connectors, where this connection is made is called a knock-out.
- Put in light bulbs.
Now we will go into more detail about how to achieve best lamp life while maintaining lamp brightness. Thus far you have set your fixtures in their locations and connected the wires from the fixtures to the hub/transformer.
- Set voltmeter to AC volts (V~)
- Connect all fixtures to the lowest tap (a multi tap transformer comes with multiple voltage taps such as 13V and 15V, at this point you would connect the hub/fixtures to the transformer on the 13V tap or the lowest tap your transformer provides.)
- Now measure the voltage with the voltmeter at the fixture closest to the transformer.
- You are looking for a reading of 11V-12V if this is not achieved on the lower tap change it to the higher tap; this again is at the nearest fixture to the transformer.
- Just a note: fixtures getting 11.5V will get 40% greater lamp life while fixtures getting 12.5V will decrease in life by 40%, so take care in setting the right voltage at this point.
- Remember the rule of thumb for transformers do not exceed 90% load rule
Extra Tips
Conceal light source as much as possible, the effect is the light not the fixture itself.
Use photocells or timers so lights are automated
Do not aim lights at neighbors
After proper installation is complete changes in the location of fixtures can easily be done.
The key to successful installation of landscape lighting is to take time in doing the work. By doing things step by step it will prevent future problems resulting in backtracking which is a huge hassle. In the end if you are unsure of what you are doing contact a professional, there are many errors that can occur that may be damaging to the new products.
A list of tools
Dielectric grease- this lubricates the shell and the socket to prevent bonding
Electrical tape
Quick connectors
Wire strippers
Crimper and cutter
Hammer
Screw drivers
Shovels
Drill
Needle-nose pliers