I recently completed a proposal for a builder in the Liberty Park community outside of Birmingham. A landscape architect had already submitted the landscape plan, and he wanted to incorporate some low voltage landscape lighting along the driveway. When I arrived for the consultation, I realized a designer’s worst nightmare. The driveway was approximately 450′ long, and the only power source was at the house.
There were three viable options for this project. First, the builder could have an electrician run a 120 volt line to the midpoint of the driveway, and provide an outlet for the low voltage transformer. This would be quite costly, and in an area with mature trees, trenching would be a nightmare. Fortunately, the cost for the landscape lighting installation would be customary.
The second option was to install the transformer for the low voltage halogen lights next to the house and wire them in such a way that overcomes the large voltage drop occurring over this long distance. For this layout, it would require a 900 watt multi-tap transformer with taps ranging from 12 volts to 22 volts. Even with that flexibility, the wiring grid would require an excessive amount of wire to ensure that all fixtures had the same amount of voltage.
The final option was to specify LED fixtures. LED fixtures consume lower wattage and have wide voltage input which allows for much greater run distances. Specifically, LED fixtures now exceed 40 lumens per watt which means the system would be designed using 8 watt fixtures. Consequently, a 300 watt transformer could be mounted at the house, and used for the system. Since LEDs have a control module which regulates incoming power, it is much easier to balance voltage in an extreme application like this. Additionally, the amount of required wire was cut in half.
Although LED fixtures are significantly more expensive than halogen fixtures, the LED option in this scenario was the least expensive. Added benefits to LEDs are an average lamp life exceeding 50,000 hours, and power consumption that is reduced by 75%.
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