THE RIGHT TRANSFORMER FOR THE JOB

WHY DO I NEED A TRASNFORMER?

One of the great things about landscape lighting is that it’s low voltage. This means that you don’t have to be an electrical contractor to install it and that the wires don’t have to be enclosed in conduit or buried very deeply in the ground. But it also means that you need a transformer, which takes the electricity powering your house (which is between 110 and 120 volts) and changes it into the low voltage power you’ll need for your landscape lighting system (about 12 volts). Every low voltage landscape lighting system needs a transformer—so the only question is, which one do you need?

WHAT'S THE DIFFERENCE BETWEEN TRANSFORMERS?

On a basic level, all transformers work in the same way. The transformer plugs into an outlet, and inside the transformer there are taps to which you can attach the landscape lighting wires.

The most important difference between transformers is their capacity, which is measured in watts. Each manufacturer offers a range of sizes, with some starting as low as 75 or 100 watts and going up to 1200 watts or more. Systems using incandescent fixtures require larger transformers because they consume more power. LED systems use less electricity, and so can take a smaller transformer to handle the same lighting capacity.

Transformers also come with different options. A basic transformer does little more than transform the power: it can be paired with a timer, an astronomical timer (that will adjust dawn and dusk times based on the location and time of year), or a photocell to automatically turn the lights on and off. More sophisticated transformers allow you to create lighting “zones,” so that you can turn some zones on and off based on use. For instance, you might have lighting around a pool or deck that you only need when those areas are being used. Transformers with zoning capabilities allow you to turn those zones on and off with a remote control or through a phone app. More sophisticated controllers can also let you adjust brightness (dimming the lights from 0 to 100%) or even adjust and change colors for special events or holidays.

WHAT TRANSFORMER DO I NEED?

To determine how large your transformer should be, you’ll need to add up the wattage of each fixture in the system. Suppose you have 10 accent lights at 3.5 watts, 5 accent lights at 5.5 watts, and 4 path lights at 4.5 watts. That’s a total of 80.5 watts in the system. You won’t want to use more than 90% of the transformer’s capacity (just to be safe), so make sure that your transformer has a minimum capacity of 90 watts. A 100 or 150 watt transformer—one of the smaller transformers on the market—would provide ample capacity for this system.

WHAT OPTIONS SHOULD I CONSIDER?

For basic systems where you’re lighting the house and a few key elements in the landscape around the house, a basic transformer should suffice. To make the lights turn on in the evening and turn off after you’ve gone to bed, the transformer will need to be paired with a timer or photocell.

If the system includes lighting on a patio, deck, outdoor living area or pool, you should consider looking into a transformer that allows you to create zones that can be separately controlled. This will allow you to save energy when the area is not in use, and to make sure the lights don’t go out if you’re having a social event that lingers late into the evening. Transformers with the ability to dim the lights or change colors are great options for those who like the ability customize the atmosphere created by the lighting.

OK, I'VE CHOSEN A TRASNFORMER. WHAT ELSE DO I NEED?

If you’ve chosen a basic model, pick up a photocell or timer so that the lights will automatically turn on and off. Most transformers come with the hardware you need to install them, but be sure to have a cordless drill and any specialty hardware necessary to hold the box on the wall, like masonry anchors if you’re mounting it on a brick wall. Transformers are relatively heavy items (and the higher the wattage, the heavier they are), so choose a sturdy place to mount it. And don’t forget that you’ll need to plug it in somewhere: if there isn’t an outlet where you’re planning to hang the transformer, call an electrician to have one installed.