blueman wrote:

Other than the fact that 110v outdoor lighting installation is
typically more costly and complicated to install, what are the
advantages and disadvantages of low voltage vs. 110v outdoor lighting?

For pretty much all of your listed considerations there is no real
difference between 120V and 12V lighting.


Considerations include:
- Selection and variety of fixtures

Comparable selections are available in both 120V and 12V versions.

- Energy efficiency

Little real difference in efficiency from a practical standpoint if you
are comparing incandescence or even halogen. Notable efficiency
differences appear when you consider fluorescent and HID fixtures which
are generally only available in 120V, with HID units only seen in true
commercial grade ($$$$) units.

- Durability/reliability

Again comparable for quality fixtures i.e. cast metal fixtures, not
plastic. The low end garbage is just that.

- Effectivenss/brightness of lights

Again comparable for most uses. For landscape, path and accent lighting
fixtures of both types are sufficiently bright. For full building facade
lighting units sufficiently bright are only commonly available in 120V
versions.

- Cost of the fixtures themselves (not including installation costs)

Again comparable. A cast metal fixture costs about the same to
manufacture, regardless of whether it is wired with a socket for a 120V
lamp or a 12V lamp.

- "Resale value"

Comparable given quality fixtures and good lighting design. An
installation with cheap plastic fixtures and/or poor lighting design
will have no resale value. A well designed installation with quality
metal fixtures will and value regardless of the system voltage.


The main difference between 120V and 12V systems is in the ease of
installation and the ease of changing the installation.

Low voltage systems require no permits, inspections or even much skill
to install. They lend themselves to "experimental" setups in the evening
while you develop the lighting plan. They are also easy to change if you
change your landscape layout.

120V Systems often require permits and inspections and require more
skill to install though it's not that difficult. Lighting plans
generally need to be worked out on paper from a landscape print and
fixture specifications which requires a fair amount of skill to get
correct. While it is possible to do temporary "experimental" setups with
120V fixtures it is much more tedious and difficult than with 12V
fixtures. Once 120V systems are installed they are comparatively
difficult to change if you change your landscaping.

Given the relative advantages and disadvantages of each type of system,
in larger installations the best option may be to use both types of
fixtures, preferably from the same manufacturer. Use the 12V fixtures
for most of the landscape and accent lighting where the landscape could
change. Use 120V fixtures for items that are both unlikely to change
such as lighting large trees, buildings or patio areas and which need
higher light levels than are available from common low voltage fixtures.

Pete C.