Types of Lighting Systems: Pro's and Con's
by John Brimacombe
Categories of Lighting Systems
High voltage (regular 120V) - This type of system requires professional installation such as conduits and sealed junction boxes because of safety concerns. For variety and brilliance of available light types this may be the best type, but once installed it's dedicated to specific locations, and is usually very expensive. If you have the funds to install this type of lighting, you probably will not need this article because your lighting professional will be giving you good advice!
Low voltage (usually 12V) - The system most beginners find are best, for a variety of reasons. They are relatively inexpensive, readily available at big box home centers such as Home Depot or Rona, easy to install, ands safe. The safety is provided not only by the lower voltage, but by the isolation provided by a step down transformer that eliminates ground shocks.
Solar powered - These systems are recently all the rage in the market, but have limited flexibility except for path lighting. Usually photocells charge batteries during the day that run low power LED lights (bluish in colour) at night. These cannot easily be focussed into a beam, so use for diffuse lighting is the best option. Some beam types are available, but focussing is poor and the beam very wide. The dark days of winter may not provide enough sunlight to make these lights charge in northerly latitude winters. Also, their long term weather durability and battery reliability are questionable.
Because of the limitations of the high voltage and solar types, the rest of this discussion will concentrate on low voltage systems.
Low Voltage System Details
Fixtures may be the spotlight type that directs a strong beam in a particular direction, floodlights with a wider beam, or diffuse type that directs the light down to illuminate low foliage or a path. These days, sealed beam bulbs (usually halogen) are used for the spotlights and floodlights, which have the reflector built into the bulb. These are usually high power (20 watt), and this power requirement limits the number of them you can use on one line. This is the type used in "fake rock" lights. Diffuse lights are lower power (typically 7 watts) inside fixtures shaped like little lanterns or mushrooms that direct the light downward.
Transformers and other Hardware
The heart of any low voltage system is its step down transformer, which is plugged into a 120V outlet and reduces the output voltage to 12 V. Low voltage wires (resembling black lamp cord) are run from this transformer to the fixtures. Any one line can have multiple fixtures, and multiple lines can be run from the same transformer.
Fixtures connect by barbs that penetrate the wire insulation, so installation is easy. Really cheap low voltage transformers have built in photocells and timers. Avoid these because they are triggered by a dark spell, after light. In winter, this may be a dark day, then darker clouds. Or foliage growing over the photocell, and triggering it every time the wind blows the leaves over the cell. Midline transformers have a separate timer based on the clock (not daylight) to run the transformer, and are more reliable for this reason alone. Transformers are available in a wide range of output powers. This power limit can vary anywhere between 100 and 600 watts, and prices seem to be about 30 cents a watt.
For example, an average yard might require five 20 watt floodlights and 14 seven watt diffuse lights, so a 200 watt transformer would just be adequate for this setup. Reasonably durable fixtures including floods, diffuse lights, plus wire for this typical setup might be about $200, so the whole system can be had for about $300.
Placement of Transformers:
Many transformers have plastic cases advertised as "weatherproof". I suggest placing these under an overhang, or even inside a garage. If you chose a cheap transformer that has photocells, just set it to "always on" and plug it into a separate timer based on clock time intervals. Also, place the lighting fixtures first, then try to put your transformer as centrally as possible to them. Long low voltage lines cause significant losses which dim the lights, especially if a lot of 20W spotlights are used on one line.