Looking to take on the task of installing landscape lighting? Installation of low voltage outside lights is something that instantly pays dividends. Not only do they give your house a more welcoming, inviting and warm appearance, but they also add a layer of security and safety to your home.

1. Landscape Lighting - Installing Low-Voltage Outside Lights
Installation of low-voltage outside lights is something that instantly pays dividends. Not only
do they give your house a more welcoming, inviting and warm appearance, but they also add
a layer of security and safety to your home. If this sounds like the kind of job you want to take
on yourself, then you'll need to become familiar with the components of a landscape lighting
system. Included on this list are the transformer, low-voltage lighting cable, fixtures, and
bulbs. Here's a quick breakdown on each of these components:
Transformer
A transformer is an electrical device that converts (or transforms) a 120 volt current into a
safer 12 volt current. This type of transformer is known as an electronic low-voltage
transformer. It contains an electronic device called an inverter. The inverter is what actually
converts a direct current (DC) to an alternating current (AC).
As a rule of thumb, it's best to size your transformer based on the cumulative wattage all of
the lights in the system will need, plus about 25% more for the cable. The additional wattage
also accounts for the prevention of voltage drop (or a reduction in voltage), which occurs the
further the line is away from the transformer. So lights closest to the transformer will shine
brightest, and those furthest away will shine less so. The quality of the wires used in the
system will also affect the degree of voltage drop.
To illustrate further and for the sake of simplicity, let's say you have just purchased a system
that includes 8 fixtures, each with a 10 watt lamp. The minimum amount of wattage you will
need is 80 watts (8 fixtures x 10 watts = 80). Next you need to multiply 80 by 1.25 (or 25%
more). So, 80 x 1.25 = 100. This is the size of the transformer you will need. You can
increase the size of the transformer even further to account for additional fixtures you may
add in the future; but generally it's not advised to exceed the load wattage by more than
100%.
Cables
As you might guess, a low-voltage landscape lighting system requires specialized cables to
run from the transformer to the fixtures. It is possible to install these cables without digging
up or otherwise disturbing an intact landscape. This is done by stapling the cable firmly into
place and covering it with dirt or mulch. But the usual method is to bury the cable in a 3 - 6
inch shallow entrenchment.
#12 SPT cable is the most commonly used wire in landscape lighting designs. This cable is
composed of tightly bound strands of copper. This distinction sets it apart from wire, which is
composed of a single strand of copper. But you will frequently hear the term “wire” used for
“cable” when describing the line used in the lighting system.
SPT is an abbreviation for Service Parallel Thermoplastic, which describes the type of cable.
#12 references the diameter of the copper strands, as set forth in the standard measurement
guide of the American Wire Gauge (or AWG) in the United States. The larger the wire, the
smaller the number for the cable. This means a #8 SPT cable has a larger diameter than a
#12 SPT cable, and therefore is able to carry a greater electrical load.

2. Although #12 SPT cable is the standard, other sizes are also used in a residential landscape
design. Pigtails (or the wires connected to the fixtures) are commonly #16 SPT cables. For
instances when a wire runs longer distances, #8 or sometimes even #10 cables are used to
handle the increased wattage load and to reduce voltage drop.
Fixtures
Low voltage landscape lighting fixtures come in all shapes, sizes, and colors. When choosing
fixtures, look for ones that are not just decorative, but also capable of being easily adjusted or
moved as changes are made to your landscape.
Area lights are designed to diffuse the light over a large object or area. These lights are also
known as wash, up, spot or outdoor flood lights. They are used to highlight bushes, trees,
statues, walls, etc. When implemented skillfully, the effect of these lights can be dramatic.
Path lights are designed to illuminate the area just beneath and spread out within a few feet of
the fixture. These lights are most commonly used on driveways and walkways. Generally,
these lights should be spaced between 6 and 10 feet apart. What you don't want is for your
walkway or driveway to resemble a mini-runway.
Bulbs
The vast majority of bulbs used in landscape lighting designs today are halogen. These bulbs
are energy efficient and shine a bright, white light. Depending on how bright you want the
bulbs to shine, each halogen bulb can range from as low as 7 watts all the way up to 75
watts. Halogen bulbs typically last about 2500 hours. If your bulbs are in use an average of 8
hours per night, this means you can expect to use about 2920 hours each year (8 hours per
night x 365 days per year = 2920 hours per year).
This stresses the importance of purchasing quality bulbs to start with and having replacement
bulbs on hand. Always remember to replace a bulb as soon as it has burned out because,
once a bulb has burned out, increased wattage is transferred to the next bulbs in line. This
increased wattage causes these bulbs to subsequently burn out before their time.
Another thing to consider is adjusting the amount of wattage in each bulb until you achieve
just the right look you are after. Keeping a supply of different watt light bulbs allows you to
experiment with different looks with each of the fixtures in your landscape lighting system.