Don't let nightfall drive you indoors this summer.
Instead, illuminate your deck. Once you
see the effect of highlighting your favorite
plants and deck features, you won't want to go inside.
And there's a safety factor, too. If you light the stairway
and railings, you won't trip over the garden hose!
In this article, we'll show you how to plan and install a
low-voltage system. The 12-volt system we show here has
several distinct advantages over standard household (120-
volt) wiring. It's much less dangerous, and the actual
wiring methods are less exacting. Even if you're a beginner,
you can safely install a simple system like ours.
A low-voltage system begins with a transformer that
plugs into a standard GFCI exterior receptacle. The
transformer converts the power from 120 volts to 12 volts
and sends the current through special outdoor cable to
light the fixtures. The only special tool you'll need to
install this system is a wire stripper. The rest are just basic
carpentry and garden tools.
To light the deck and the landscape around it, we used
13 fixtures, two transformers, cable and connectors. Pay close attention to the
planning section and drawing, and follow our photo
series for techniques and tips on how to safely wire your
Our deck lighting layout in Figure A features a variety
of fixtures and mounting methods to show the different
methods of running cable to individual locations and
determining the wattage loads for each circuit. Follow the
dotted lines for each circuit to the type of fixture we used
in our story.
Figure A: Deck lighting layout
Figure A: Deck Lighting Layout
Use only outdoor UL-listed lighting
transformers, cable and lights for your
project. If you plan to purchase individual
components instead of a kit, check
with the product manufacturers to make
sure your components are compatible.
See below for photos and descriptions of the lights used in this layout.
Planning your lighting
One great feature of a low-voltage system is the wide variety of
fixture finishes and shapes to choose from to complement your
home. You'll find a limited selection at home centers, but a wider
variety at local lighting specialty stores and through online
catalogs. Keep in mind that you can
buy complete ground-level landscape lighting kits, but you'll
have to buy individual components (transformer, cable, fixtures,
lamps and connectors) for a deck lighting system.
Before you buy anything, make a sketch of your deck along
with the chairs and tables. To simulate the effect of each fixture
on and off your deck, buy an inexpensive clamp-on work light
with a metal reflector shade. Along with the clamp light, buy
25- and 40-watt standard frosted incandescent bulbs and a 45-
or 50-watt reflector flood bulb. As evening approaches, install
the 25-watt bulb and plug the clamp light into an extension
cord. Then clamp the lamp at different locations on your deck,
turn it on and observe the lighting effects. This will simulate the
various fixtures we used in our deck plan. Keep the light low
(about 2 ft. off the deck surface) to prevent glare. Try a 40-watt
bulb if you want more light. Mark the most desirable locations
on your drawing.
Pay particular attention to lighting areas like the stairway and
transitions to different deck levels. For these locations, install the
spot bulb for more focused light.
Now take the clamp light into the yard around the deck
and clamp it to various stakes so you can see where you
can illuminate a path, plants or other features along the
perimeter of the deck. Mark the best spots on your drawing.
You'll want to incorporate several lighting techniques
for a variety of useful and decorative effects.
Match the transformer to the wattage of the circuit
We chose two lighting
circuits, each controlled
by its own transformer
with built-in timer, as
shown in Figure A. This plan gave
us several options.
The circuits could go
on and off at different
times and we could create
a dedicated deck lighting plan and
another landscaping plan. Once you
figure out how many lights you'll have on
each circuit, add up the wattages and buy large enough
transformers to power each circuit. (If you buy a landscape
lighting kit, all the materials and connectors will be
included.) Transformers generally come in 100-, 150-,
300-, 600- and up to 1,000-watt capacities. The total wattage of all the lamps
in an individual circuit must not exceed the wattage rating
of the transformer circuit. Follow these guidelines:
- Add the wattage for the seven lights on the deck: four
lamps at 26 watts and three at 35 watts, for a total of
209 watts. You may want to add a lamp or choose a brighter bulb later, so use a 300-watt transformer for
- Next, calculate the total wattage for the perimeter of the
deck. We had six lights. Five of the lights had 50-watt
bulbs; the other had an 18-watt. This added up to 268
watts, so we selected another 300-watt transformer to
supply power for the landscape circuit.
- The transformers plug into a 120-volt exterior receptacle
(Photo 1), so if there's not one nearby, you'll need
to install one or have it installed by an electrician.
Cable and connectors complete the package
You'll also need to buy cable for your light fixtures.
Don't skimp here. If you have long runs of 50 ft. or more
as we did, buy 12-gauge outdoor lighting cable and you
won’t have to worry about a voltage drop along the circuit
that could dim the lights near the end of
the line. Measure the total distance from the
transformer to the last light of each circuit and
buy an extra 20 percent for unforeseen
paths that wire may have to take.
You'll need two types of cable connectors:
one for dry areas inside the
panels and planters and another for wet
areas where the cables will be buried in
the soil outside of the deck. The first type (Photo 5) is a
standard wire connector used in common house wiring
connections. The other connector (Photo 8) is filled with
a sealant that coats the wires as you twist the connector
onto the bared ends of the wire. These cannot be reused
but offer excellent protection for years of service. Also
buy some cable fasteners to secure the cable to the deck
framing (Photo 2).
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The photos show the basic installation
steps. Start at the transformers (Photo
1) and run the cable in the shortest
route to all the lights. In general, run
the cable out of sight as much as possible
and be sure it's protected. You don't
have to make connections inside electrical
boxes as with 120-volt systems.
Mounting procedures vary, so read the
directions included with your fixtures.
If you want to add more lights or
change to brighter lamps, be sure your
transformer can handle the extra load.
Note: Do not run the cable into concealed
areas like the exterior walls of
your house. If you want lighting
mounted to the walls of your house,
you'll need to buy 120-volt fixtures, follow
conventional wiring methods and
have your work inspected by your local