FEATURED ARTICLE
Published: 11/15/2022
A low-voltage transformer is the brains of your landscape lighting system. It regulates the power to your outdoor lights, controls when they switch on and off, and makes your entire system safe all around. Whether you’re designing a brand-new outdoor lighting scheme or upgrading an existing one, a transformer is a non-negotiable component. While DIY landscape lighting transformer installation might appear like an intimidating ordeal, determining what kind of transformer you need and where the transformer should be located are the keys to a smooth-as-silk installation experience. We’ll identify factors to consider when selecting the optimal transformer for your outdoor lighting as well as the simplest, safest way to install it.
Most households operate on 120 V (volt) power, which is perfect for interior lighting that utilizes high voltage lighting. Landscape lighting, however, is typically supplied in lower voltage (12 V) spread out through several different lights. A transformer converts the 120 V electrical current supplied from your house down to the 12 V required for each low-voltage landscape lighting fixture in your lawn.
Think of the power adapter for a laptop. It converts the electricity from the wall outlet into a form that’s usable for the laptop. The relationship between transformers and LEDs is similar. LEDs are considered electronics—not standard light bulbs—so they run on DC power. Because a transformer produces AC power, it’s tasked with modulating the LED voltage to ensure safe operation.
Purchasing an adequately sized transformer requires tapping into your third grade math skills. First, you must find the fixtures you want then decide how many fixtures you need for your yard. Each fixture uses a certain number of watts, while each transformer can only support a maximum number of watts. Therefore, it’s imperative that you determine the total wattage exhausted by your fixtures in order to verify that your transformer can sustain the workload. To calculate the minimum watts the transformer must support, simply multiply the number of watts per fixture by the number of lights needed.
Let’s say you want six 18 W path lights for a walkway.
18 W (# watts per fixtures) X 6 (# lights needed) = 108 W (minimum watts transformer must support)
According to our calculations, you’ll need a transformer that can handle 108 W. That was easy, right? Well, there’s a little more to it. According to the National Electric Code, transformers used for landscape lighting cannot exceed 80% above the wattage load to account for miscalculations made when totaling up all the loads, wiring, and connections. The transformer’s extra rent space also makes it easier for adding extra fixtures over time as the landscape matures.
Now that we know we can’t put more than 80 watts of total load on a 100-watt transformer, let’s edit our example’s estimated transformer size. If you want six 18 W lights for your path lighting application, you will need a transformer that can manage around 130 watts.
You’re probably asking yourself: What can happen if I overload the transformer with too many watts? It’s the same thing that happens to your brain if it’s overloaded and overworked. The net result of minor, incremental increases in loading capacity over time can cause the transformer’s insulation of windings to become brittle and crack, aging the device prematurely and thereby weakening your entire system.
Because a transformer is a complex piece of equipment, you might assume that it should always be placed indoors to safeguard it from outside elements. However, they’re perfectly prepped for outdoor insulation as most transformers are designed to be waterproof and weatherproof. Transformers’ connections are generally on the underside, leaving any open, vulnerable areas pointed downwards and shielded by the transformer’s body. Its downward-falling direction means that rain is unlikely to reach the inside of the transformer.
Place the transformer as close to the lights as possible. A longer wire run weighs the risk of voltage drops (the flickering or dimming of lights).
Keep the transformer within reach of a GFCI outlet, which has a built-in ground fault circuit interrupter used to cut the power in the event of a ground fault, protecting your home from risk. If you don’t have a GFCI outlet, it’s important that you get one installed prior to installing a transformer. Don’t plug a transformer into an ill-protected outlet.
Pro-tip: Test the GFCI outlet before landing your transformer’s location. Need we say more?
Place the transformer at least a foot above the ground to avoid water damage from splashes.
Decide how the transformer will be mounted, even though mounting equipment is included with most transformers. If you’re installing it onto a brick exterior, you’ll need a masonry bit, adequate anchors, and stainless steel mounting screws. If you’re mounting onto a post, you’ll want at least a four-by-four post mounted into a concrete footing with stainless steel screws.
Confirm if the location will have Wi-Fi connectivity if your transformer comes with Bluetooth capability. Wi-Fi-enabled transformers fuel the convenience factor by allowing you to manipulate your lights from your phone without manually setting any timers. The trade-off, of course, is that they must be within range of your router to operate. It’s best practice to test this in advance by standing in the transformer’s potential location and verifying wrinkle-free Wi-Fi connectivity with your smartphone. If the Wi-Fi signal isn’t relaying maximum strength, you’ll need to purchase a signal booster or reevaluate the transformer’s location.
Mounting the Transformer
Step 1: With the transformer unplugged, punch out the knockout in the bottom for cable access. To do this, place the edge of a screwdriver on the outer edge of the knockout ring and give it a quick, solid blow and continue until the plug is removed.
Step 2: Install a terminal adapter in the bottom of the transformer using the half-inch terminal ring clamp to confirm the adapter’s tight fit.
Step 3: Whether you mount the transformer directly to your home or to a post adjacent to your home, the transformer must maintain at least a foot of clearance between the bottom of the transformer and the ground. Mark the top hole with a pencil and, using a hammer drill, drill a hole about 1 inch deep.
Pro-tip: Do not mount a transformer on vinyl as a transformer can get very hot.
Step 4: Insert a masonry anchor and screw into the hole and set them in place.
Step 5: Thread in the anchor screw, leaving about 1/8 of an inch gap so that the transformer can hang onto the screw.
Step 6: With the transformer hanging vertically from the inserted screw from the previous step, mark the bottom hole. Slide the transformer aside and drill the hole for the bottom anchor sleeve.
Step 7: Piece your anchor and screw together, place them in the hole, and secure it with the screwdriver.
Step 8: Now that the bottom screw is in place, secure the top screw.
Setting the Wires
Step 1: Measure the distance from the ground to the terminal adapter then, with a PVC pipe cutter or pipe saw, cut the PVC conduit accordingly.
Step 2: Run the end of the wire through the conduit and into the transformer before twisting the conduit into the socket.
Step 3: Once the wire and conduit are in place, use a shovel to backfill the hole at the base of the transformer.
Connecting the Wires
Step 1: Separate the two ends of the wire using wire cutters then pull them apart.
Step 2: Using wire strippers, leave 1 inch of the copper wiring exposed.
Step 3: Loosen the screw clamps on the voltage lugs and twist the wire ends.
Step 4: Insert one of the conductors—it doesn’t matter which one—on the common side (left side, often labeled COM) and tighten it down, giving it a slight tug to confirm its stability.
Step 5: Place the other inductor in the opposing voltage terminal, tighten down, and secure.
Step 6: Install the control device (timer) for your transformer by removing the terminal plug from the transformer and plugging it into the receptacle on the timer. Now plug the timer unit into the transformer’s receptacle. *
Step 7: Close and latch the door then plug in the transformer.
*If your transformer includes an integrated timer or photocell, skip and continue to the last step.
Congratulations on your successful low-voltage transformer installation. For any questions about landscape lighting transformer installation or other Landscape Lighting products, contact our Customer Service team to set you in the right direction.
Depending on fixture type and customization as well as yard size, a landscape lighting system can cost as low as $500 for a bare-bones system and as high as $7,000 for larger, more opulent projects, with the national average sitting around $3,500.
When installing low-voltage landscape lighting, you will need a transformer to step down the 120-volt output from your home’s electrical system to the 12 volts used by low-voltage landscape lights.
Magnetic low-voltage transformers can run for about 15-20 years while electronic low-voltage transformers can operate for about 5-6 years.
Kevin B. Goode
Product Specialist at Lighting Warehouse
Monday - Friday
Speak to us at 855-444-8424
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