Line or high voltage lights are fixtures which are powered by 120 volt electricity that is the standard output of the electrical grid in the US. Low voltage lights use a transformer which reduces the high voltage output down to 12 volts. Low voltage lights have many advantages over the high voltage alternatives and are frequently utilized in outdoor landscape designs.

First of all, 12 volt systems are significantly safer to install and maintain. Most individuals can handle putting in low voltage outdoor lighting on their own and there isn't any the danger of electrocution or the burden of acquiring permits from the government. If a light fixture breaks or if you opt to add to or alter the layout these modifications can also be done independently. So for many people utilizing a 12 volt system for landscaping means avoiding the expense of employing an electrical contractor.

There is also a greater choice of fixtures readily available for outdoor 12 volt systems and these types of lights are usually smaller and easier to blend into the terrain. Low voltage light bulbs also last considerably longer than standard incandescent bulbs. Basic tungsten halogen bulbs can last 3 time longer, compact fluorescent bulbs 10 time more time and LED lights as much as 50 times longer. This means that less time is spent maintaining and replacing lights and over time fewer bulbs will have to be purchased. Low voltage bulbs are still more expensive to purchase than incandescent lamps and in the case of LEDs far more expensive. This initial cost is usually recouped with time through longer bulb life as well as reduced energy consumption. The time to recover the original outlay will be directly determined by the utilization of the lights and the price of electricity which varies greatly by location.

As stated, low voltage lights consume less energy than high voltage ones. A common misunderstanding is that low voltage lights automatically consume less electricity because they are a "low voltage." But electricity usage and subsequently cost is driven by the total wattage of the light bulbs in the system, not the underlying voltage. So a 200 watts, 120 volt system will use the same or even a little less power than an equivalent 200 watts, 12 volt system. In this case, the 120 volt lights consume less power in total because the transformer in the low voltage system also draws some electricity. However, low voltage light bulbs are more efficient and output more light (measured in lumens) for the same wattage. Taking advantage of this efficiency, it is possible to construct a low voltage system that gives off the same amount of light using only 1/2 to 1/3 the wattage of a high voltage system. The potential annual savings on your electrical bill can be significant and can be estimated using the following formula:

(Line System Total Watts - Low Voltage Watts) x average hours operated per day x days per year operated x cost per kilowatt-hour /1000.

The cost per kilowatt-hour (KWH)in the US varies greatly by location and ranges roughly from 7 cents per KWH in North Dakota to 26 cents in Hawaii. These numbers are subject to change at any time and are only intended to illustrate the breadth of the range in costs. The rate in your location can be found on your electric bill and you should include taxes and other fixed fees to produce an accurate estimate of the savings.

Here is a sample calculation based on a middling cost number of 15 cents per KWH and ten 100 watts incandescent lights replaced by ten 50 watt halogen lights which will provide at least an equivalent amount of illumination:

High Voltage System - 1,000 watts total

Low Voltage System - 500 watts total

Average Daily Hours of Operation - 8 hours per day

Days operated per year - 365

Savings = (1000-500) x 8 x 365 x.15 /1000 = $219 per year.

For bigger systems and higher cost locations this annual savings can be much greater.