Low Voltage Cable

When you install outdoor lighting yourself, you’ll need to be sure you have enough low voltage cable.  You might be tempted to plug the transformer into an extension cord to make it even more convenient and close to your fixtures so that you need less cable, but you should never do this.  You should mount the transformer within about a foot or so of your outdoor 110 volt outlet and be sure your outlet has weather protection while in use to avoid any shock hazards.

It’s best to use the shortest amount of low voltage cable that you need, for a couple of different reasons.  First of all, less cable is easier to hide.  Since low voltage cable does not have to be buried like high voltage cable does, it makes the entire lighting fixture more portable and easy to adjust. But you’re left with unsightly cable stringing from the transformer to light, or between several lights. You’ll want to hide that cable with mulch or decorative rocks.  And if there are several feet of low voltage cable to hide, that becomes more difficult.

Second, the longer the low voltage cable is that goes from the transformer to your light fixtures, the less likely those fixtures will be to run at full power.  You can have bulbs that are dimmer than they should be or flickering bulbs.  This can put premature wear on your fixtures because they’re not operating exactly as they were designed to operate, and can simply look less fantastic than you’d hoped.

The reason the length of the low voltage cable affects the light performance is what’s known as voltage drop. The longer the cable, the less voltage will actually reach the end of it. So your fixture might be designed for 20 volts, but because the low voltage cable is so long, only 12 reach it.  This is a common problem with outdoor lighting, and it can sometimes be a challenge to fix.

One option is to purchase a larger low voltage cable.  If the cable is too thin, voltage drop is more likely.  A cable with a larger circumference will let more volts pass freely through its entire length.  If changing the length or circumference of the low voltage cable isn’t an option, then look into a multi-tap transformer.  These have several different outputs in different volts, unlike a standard transformer.  You can hook your fixtures with short cables into the lower voltage taps and reserve the higher voltage outputs for your lighting that suffers from voltage drop.

If you’re undecided between high and low-voltage lighting, consider that the need to bury high voltage cables locks your design in place, and a contractor is required for installation.  But with low voltage cables, the most you’ll need to do is mount a transformer near your outdoor outlet and plug it in. And if you want to change the lights later or alter your design, the low voltage cable is easily moved to another part of your yard or garden.