Low voltage landscape
lighting systems are safe, economical, energy efficient and provide numerous
benefits for modern homeowners. Lighting can be used to provide safe access
near paths, drives and entry areas. Outdoor lighting increases security by
discouraging potential intruders. And the beauty of garden and home can be
dramatically enhanced by showcasing architectural and plant features with
dramatic lighting techniques.
One common technique is up lighting,
which focuses light and attention on an object from a low fixture location.
The object can be a shrub, tree or architectural feature like a gazebo or
arbor. Bullet or well type fixtures are specified according to the mature
size of the plant or the size of the hard cape area to be illuminated.
Path lighting uses low fixtures which direct illumination down and outward.
These fixtures are shielded on top to prevent glare. They are used along
walks, stairs and anywhere else that safe night access is required.
Another technique is down lighting, or moonlighting. Usually accomplished
with bullet type fixtures placed above eye level on a structure (or even in
a tree), this technique illuminates general areas for safety, security and
aesthetics. Fixtures and lamps are chosen for the required brightness and
width of illumination.
Backlighting, or silhouette lighting, provides a special effect by
illuminating a fairly large surface (like a wall) using a wash light
fixture. This causes objects in front of the lighting to appear as
silhouettes.
The technique of shadowing also uses lights directed toward walls, but they
are placed in front of the objects, so shadows play on the wall.
Numerous other techniques, and combinations of techniques, are available to
increase your home security, safety, enjoyment and value. The practical and
aesthetic effects created by landscape lighting are limited only by the
existing features of the architecture and landscaping and by the creativity
of the designer.
Before deciding what and how to light, we must first ask "why light?" Our
design decisions are dependent on proposed uses for landscape lighting...for
safety, security, property value, or enhancement of the beauty of the garden
and structures. Most likely, the answer will be a combination of two or more
of these uses. A specific technique can be employed to satisfy more than one
requirement...for example, up lighting a prominent tree near the house
entrance will provide safety, security and aesthetic enhancement.
Landscape lighting design is very similar to the design of the landscape
itself: we must determine focal points, use areas, traffic patterns, outdoor
"rooms," style, mood, etc. We need to consider how the proposed lighting
will enhance the form, color and texture of the soft and hard landscape
elements. Lighting should serve to unify both interior and exterior design
themes, conceal what may be unattractive and shape the view of the landscape
at night.
The design process should begin with a site map, drawn to scale, showing all
landscape features and areas that need lighting. Fixtures and lamps are
chosen for each area based on the desired effects ...path lights for safe
passage along walks and stairs, wash fixtures for silhouette effects against
a wall, etc.
One common mistake is to over light; low levels of light create subtle
beauty, and are often also sufficient for safety and security. Use brighter
lighting effects for focal points, and consider the effects that different
light intensities will have on the overall design.
After deciding on the size and placement of lighting fixtures, the
electrical system is designed. The heart of the system is the transformer,
which converts the household 120 volts into safe, efficient 12 volts, and
delivers this voltage to several circuits. Using appropriately sized cables
and approved connectors, fixtures are connected to the transformer.
Group fixtures in zones determined by the distance to the transformer. The
number of fixtures on each circuit will be limited by the wattage of
individual lamps, distance to the transformer and associated voltage drop in
the circuit.
Voltage drop calculations are critical; excess voltage results in hot lamps
with greatly shortened life - insufficient voltage results in weak,
ineffective lighting. The design challenge is to match cable size, total
lamp wattage and circuit length to produce voltage within the range of 10.5
to 12 volts. A new generation of transformers uses a multi-tap configuration
to provide voltages in excess of 12 volts for those zones at a sufficient
distance from the transformer. (The excess voltage is reduced by the length
of run to the first fixture). This allows greater design freedom and
efficiency.
A common practice among lighting
designers and installers is to allow for plenty of movement of the fixture
locations. By leaving extra cable at each fixture, changes can be made to
the system after installation, and after several years of plant growth.
This has been a very brief introduction to the world of landscape lighting.
There's a vast amount of additional knowledge available for the homeowner to
consider, whether he or she wishes to design and/or install a home lighting
system, or merely to learn more about the possibilities. The following are
highly recommended sources:
"The
Art of Outdoor Lighting : Landscapes With the Beauty of Lighting"
by Randall Whitehead
"The
Landscape Lighting Book" by Janet
Lennox Moyer
...both available from online
and offline sources.
Here is an example of a landscape lighting plan prepared for a recent
client. It's a small project, with just four circuits:
http://clearwaterlandscapes.com/lite_plan.gif
Happy Trails,
Dan Eskelson
Clearwater Landscapes, Inc.