What Size Transformer Do I Need for Landscape Lighting?

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Not only does landscape lighting add a certain aesthetic appeal to a property, but it also adds security and safety. Once you have completed the design of your landscape lighting, you can move on to determining what the size of your low-voltage transformer needs to be. Most transformers will usually fit into the 150W – 900W capacity range.

Matching the landscape lighting design to the size of the transformer is essential for efficient function and operation of the entire system. House current, which is usually 120V, experiences a reduction to around 12V – 20V by a transformer. This new current is necessary for operating low-voltage landscape lighting setups.

The majority of transformers on the market come with connections for lights that have different wattages, which allows for more versatility. Some of the other features that most low-voltage transformers come with are photocells which turn the lights on when it gets dark, motion sensors to turn the light on and off, and timers that can be programmed.

So what size transformer do I need for landscape lighting? Let’s take a look at everything you need to know.

Things to Consider Before You Start

It’s important to remember that if you connect lights with a low voltage directly to line voltage power, they are going to burn out instantly as a result of the higher 120V. This is why you need to use a low-voltage transformer as a power source. The transformer can also be connected to your main source of power so that your landscape lights run correctly every night.

If there is no GFCI outlet available, you should hire an electrician who will install one for the new low-voltage lights, before installing where the transformer will be put where it can’t be seen. If you choose to use the magnetic transformers for landscape lighting, which are generally more powerful, then you should not exceed 80% of its maximum rating of wattage.

If you want to determine the number of 12V lights you can power with one low-voltage transformer, you will need to look at the VA and wattage ratings for the fixtures you are going to install. After you have made the calculation using the number of lights in the lighting system, you can then find a low-voltage transformer with a higher wattage rating.

How Many Landscape Lights Can Be Installed On a Low-Voltage Transformer?

You need to take some things into consideration when it comes to the power specifications of your transformer. If you calculate the voltage-amps rather than the watts, then you’ll be able to determine the true power draw on the line. This is one of the main reasons that this number is used, as it helps you avoid buying a landscape lighting transformer that does not have enough power for your lighting system.

For example, if you wanted to connect ten landscape spotlights to one small transformer, using lights that use 2W / 4VA / 20W halogen light output power each, you will use a transformer with a 100W rating. The formula used is: 10 lights x 4VA = 40 voltage-amps.

The Importance of Wiring

When you are trying to determine which wire gauge you should use for your lighting system, you should remember that there are different benefits and drawbacks to different gauges. Smaller sizes of wire are generally more budget-friendly, but they also reduce the power distance that you light gets in the ground, and might also need a conduit to protect them.

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Landscape Lighting Tips

It’s important to remember that a little goes a long way when it comes to landscape lighting. Your eyes don’t need as much light when you’re outside than they do when you’re inside, so a good way to plan your system out would be to take a walk around your yard at night.

Try to imagine what you want the lighting system to look like, and how you want the light to interact with your outdoor space. It would be best if you customized the plan to those needs and desires to see the best results.

You will also run into different issues with outdoor lighting than you would with lighting indoors. For starters, you won’t have much of an issue with reflections, since most outdoor surfaces are quite dark and not very reflective. But, shielding and positioning are more important outdoors, as you’ll want to prevent glare as much as possible.

Glare occurs when a light source is too bright or big, which then reflects into people’s eyes and becomes blinding. Landscape lighting will also need to be quite sensitive to direct and indirect light.

Direct landscape lighting, like a downlight outside a door, for example, will mostly brighten the area that it is pointed to, and maybe some of the surrounding. Indirect light will illuminate the nearby surrounding area, creating a soft wash of light.

Avoiding Outdoor Light Pollution

Poorly installed landscape lighting, or simply too much lighting, can create undesirable light pollution that reaches the inside of your property, temporarily blinds glare, makes the stars less visible, and wastes money and energy. Here are some things you can do to avoid light pollution outdoors:

Shield the lightbulbs: Try to use fixtures that feature shieldings and reflectors. These will concentrate the light to areas you want to illuminate, rather than washing out an area.

Control the lights: Zones that are lit separately using controls, timers, motions sensors, or dimmers will activate the lights only when you need them, and you’ll be able to switch them off as you see fit.

Carefully aim lights: Try to do the positioning portion of your landscape lighting installation at night, so that you can see where they point. Be sure to check their positions regularly, and adjust them as necessary.

Reduce wattage as much as possible: Higher wattage ratings will create harsher, brighter light while leaving the aesthetics untouched and not improving security. Low-wattage bulbs are usually more than enough to create adequate light without these problems.

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