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The Brilliance of Efficiency: Avoiding a Sharp Voltage Drop in Low Voltage Landscape Lighting Systems

 

As you probably already know, low voltage landscape lighting is a great idea if you wish to illuminate your landscape without putting a heavy strain on your electric bill. Low voltage lights achieve this task by utilizing a transformer that converts higher voltage electricity into an electrical current that is lower than your everyday, run-of-the-mill light bulb yet still offer bright beams to light up your landscape.

 

There is a slight downside to using low voltage lighting and it varies in extremity, depending on your system’s configuration. Voltage drop occurs when the electrical current loses more and more of its voltage as it travels down a cable, resulting in lights that dim more the farther away they are from the transformer. This disadvantage affects many systems that run low voltage lighting for landscape lighting needs. Fortunately, we at eLight Spot can show you ways to avoid the voltage drop so that you may get the best out of your landscape lighting system.

 

There are three factors to keep an eye on to effectively reduce the voltage drop: cable gauge, the length of the run of lights that the transformer supports and the amount of fixtures on the run.

Cable gauge can affect voltage drop drastically. The larger the cable gauge, the lower the drop. The length of the run affects voltage drop as well. Multiple short runs from a single transformer are worlds better than a single long line because the closer fixtures enjoy more light than those farther away. The amount of fixtures on a run also affects the voltage drop. Fewer fixtures generally equate to more evenly distributed voltage, and subsequently evenly distributed light.

 

The most efficient lighting systems benefit from well thought-out designs that allow all lighting fixtures to share the voltage of the transformer evenly, resulting in a run of lights that each receive about the same amount of current and therefore output about the same brightness of light. Follow these steps to ensure that you get the best out of your low voltage lights and to minimize any voltage drop you may encounter.

 

  • Group ‘Em: If you have a few fixtures that will be placed 15-30 feet away from the transformer, group these fixtures together on one line. Fixtures that will sit 25-40 feet away go on another line. The point behind grouping the fixtures this way is to have the fixtures be about the same distance away from the transformer so they enjoy less of a voltage drop altogether, appearing to light with brightness similar to their neighboring fixtures.
  • Break It Up: So you don’t overload your transformer, break up a single line that exceeds 150 watts into two even lines of 75 watts. This breaks up the run and allows each light on each respective run to shine at about the same voltage. Remember, each lighting fixture should have 10 to 12 volts running to it. Multiple runs ensure a low voltage drop.
  • Avoid “daisy chaining”: Daisy chains are uninterrupted runs that house more than 3 light fixtures in one line. This creates a huge voltage drop because the first light fixture gets the highest amount of current while each fixture thereafter gets a smaller and smaller amount. The last light will be noticeably dimmer than the rest and will poke fun at your lack of sound planning in design. Instead, split a long run into two or more runs. That way, the electrical current is more evenly distributed among the light fixtures.

Below are some ways to design your landscape lighting system so you can avoid daisy chains and get the best out of your low voltage lighting fixtures.

  • Loop—Reduces voltage drop by producing a uniform light output. Be sure to connect the same wire leads to the correct terminals in the transformer by marking the cable on one side.   
voltage drop loop
                                                     
  • Split-Load—Run recommended length of cable in two or more directions.              
voltage drop split load
                  
  • T-Installation—Best to use heavier gauge cables for this installation, which allows even distribution of power to the center and equally down both sides of the run.         
voltage drop t split        
                                                                                                        

Short cable lengths, multiple transformers and low fixture wattages all add up to low voltage drops. Also, having the right size transformer helps things along quite a bit! To calculate the transformer size you need, add up all the wattages of all the lamps you plan to use. The transformer that closely matches this number is the right transformer for your system. While excess transformer wattage doesn’t hurt, if the total amount of wattage from the lamps far exceeds that of the transformer, consider splitting up the lights between two transformers or simply invest in a more powerful transformer.