How to Install Trex® LED Deck Lighting

Know your options

Trex Lighting offers several fixture styles that can be used individually or combined to create layers of light throughout a deck. The right combination depends on your deck's layout, how you use the space, and the atmosphere you want to create.

• Post Cap Lights: Installed on top of railing posts, these lights cast a soft, downward glow around the perimeter of the deck. They're available in profiles designed to complement several Trex railing systems.
• Under-Rail Lights: Installed beneath the bottom rail, these low-profile lights create a continuous glow along the railing. They're available in 30-inch lengths for 6-foot railing sections and 42-inch lengths for 8-foot sections. Each rail section requires two fixtures. These lights can also be trimmed to fit shorter railing lengths.
• Linear Riser Lights: Installed on stair risers, these lights create a sleek line of light across each step. A concealed clip-in design keeps the fixtures unobtrusive while casting a soft glow across the treads.

Oval Riser Lights: These compact lights mount individually to stair risers for a more traditional look. Plug-and-play connections make it easy to install multiple lights along a stairway.

Choose your transformer

Trex outdoor lighting operates on 24-volt direct current (DC) electricity. Because your home's electrical system supplies alternating current (AC), a transformer is needed to convert it to the 24-volt DC power the lights require. Compared with 12-volt systems, 24-volt systems experience less voltage drop over long wire runs, reducing the likelihood of lights appearing dimmer farther from the transformer.

Trex offers 60-watt and 96-watt transformers. Choose a transformer based on the number of lights you plan to install and how they'll be divided into branches. As shown in the chart above, dividing the lights among multiple branches increases the number of lights a transformer can accommodate. When calculating transformer capacity, three Oval Riser Lights count as one light.

Develop a plan

Before installing the lights, develop a wiring plan that identifies the locations of the lights, splitters, and extension wires. Run the heavier-gauge wire attached to the transformer toward the center of the lighting runs, then use splitters to distribute power to the individual lights. With the exception of Oval Riser Lights, which can be daisy-chained together, each light requires a connection to a splitter, and extension wires connect the splitters to one another.

Whenever possible, incorporate the lighting system as the deck is being built. On low decks, for example, it's much easier to position splitters and run extension wires before laying the decking. Post Cap Lights and Under-Rail Lights are best added as the railings go up, while stair lights are easier to work with before the treads and riser fascia are in place.

Order your materials

With your lighting layout and transformer selected, use the materials checklist below to determine which lights, extension wires, splitters, and other components you'll need. The following material lists above correspond to Examples 1 and 2 above:

Tools and Materials Needed

• Tape measure
• Pencil or marker
• Drill/driver with bits
• Screws rated for treated wood (for securing splitters)
• 1-inch Forstner bit
• 1/2-inch drill bit
• 1/2-inch auger bit (at least 8 inches long)
• Insulated wire staples (staple gun optional)
• Mounting cable ties
• Soft rubber mallet
• Painter's tape or duct tape

Small pliers

Install the transformer and timer

Plug the timer into a GFCI-protected outdoor outlet with a weatherproof cover that keeps rain and snow out even when the lights are plugged in. Install the timer vertically with the receptacle facing down, at least 12 inches above ground level. Position it where the built-in light sensor receives natural daylight, so the dusk-to-dawn feature works properly. An optional dimmer and remote control can be purchased separately.

Install deck lighting splitters

It’s easier to connect wires to the splitters before fastening them to the framing. However, on ground-level decks, where access from below is limited, it’s best to install the splitters before the decking goes on. Position splitters far enough from adjacent framing members to make connecting and disconnecting wires easy. Also, leave enough clearance above the splitters so the decking won’t interfere with the connections once it’s installed.

• Under-Rail Lights: Position each splitter within approximately 8 inches of the base of the post. This allows the light’s 19-inch lead wire to reach the splitter without an extension wire.
• Post Cap Lights: When using a 5-foot extension wire with a Post Cap Light installed on a standard-height post, position the splitter within approximately 16 inches of the base of the post.
• Oval Riser Lights: Because these lights can be daisy-chained, a standard-size stairway typically requires only one splitter. For wider stairs with two runs of Oval Riser Lights, install the splitter near the center of the stairway so it can feed both runs.

Linear Riser Lights: Install the splitter within 6 inches of the first light in the series. You'll also need a Y-Splitter between each pair of lights. 

Run extension wires between the splitters

Like the splitters, extension wires are usually easier to install on low-level decks before the decking is installed. Before running the wires, keep in mind that each splitter has one male input connector and five female output connectors. The short lead wire attached to each light has a male connector, so orient the extension wires with the female connector toward the lights they will serve. Remove the protective caps only from the output connectors where lead or extension wires will be attached and leave the remaining caps in place.

Extension wires can be looped beneath the joists or passed through 1/2-inch holes drilled through the joists. Secure the wires to the framing with insulated staples designed for low-voltage wire. Options include staples secured with nails, screw-down staples, or insulated staples installed with a cable-staple gun.

Don’t cut extension wires to length. Trex Lighting is a plug-and-play system, and cutting the wires could cause failures and void the warranty. Instead, coil excess wire and secure it to the framing with a mounting tie.

Install deck post cap lights

Some steps for installing Post Cap Lights need to be completed as the deck is being built. Because not every deck is built the same way, you may also need to create a unique route, not shown here, through the framing members for some of the wiring.

It can be helpful to power up the system after installing each light, making problems such as loose connections or damaged wires easier to track down.

Post Cap Lights on Sleeved Wood Posts

Installing a Trex Post Cap Light on a sleeved wood post begins before the decking is installed and is completed after the decking is in place. Cut the wood post about 1-1/2 inches below the final height of the Post Sleeve to leave room for the wiring and Post Cap Light. In this installation, the blocking that supports the post was positioned low enough for the wire to pass over it. If the blocking is already installed, you may need to drill through or notch it to create a path for the wire.

Step 1: Create a path for the wire

Trex Post Sleeves have channels that provide space for the wire. Choose a channel, then drill one or more holes through the bottom of the post and/or framing as needed to create a clear path from the top of the post to the nearest splitter below. Don’t run the wire along a side of the post where a railing will be attached.

Step 2: Install and secure the wire

Run a 5-foot extension wire along the post and down to the splitter, leaving a few extra inches at the top. Secure the wire to the post with tape. Make sure the wire runs straight up the post and aligns with the channel in the Post Sleeve.

Step 3: Make the connection

Connect the extension wire to the splitter. Coil any excess wire and secure it with a mounting cable tie, then secure any loose wire to the framing with staples.

Step 4: Install the post cap light

Once the decking is installed, slide the Post Sleeve down over the post. Connect the Post Cap Light lead wire to the extension wire, then install the light, taking care not to pinch the wires. You may need to gently tap the top of the light with your hand or a soft mallet to seat it snugly and flush with the post.

Post Cap Lights on Aluminum Posts

To install a Trex Post Cap Light on an aluminum post, route an extension wire up through the hollow post after the decking is installed but before the post is secured.

Step 1: Drill a hole through the deck surface

When marking the holes for the aluminum post base fasteners, mark an additional hole in the center that aligns with the opening in the bottom of the post. Drill a 1/2-inch hole through the decking. If a joist or beam is directly beneath the hole, you may need to use a longer auger bit and angle the hole to one side.

Step 2: Fish the extension wire through the post

Fish a 5-foot extension wire down through the hole in the decking, then up through the aluminum post.

Step 3: Secure the extension wire

Before installing the post, use painter’s tape to secure the extension wire at the top and prevent it from falling back inside. In wet weather, use a cable tie instead of tape to temporarily hold the wire in place.

Step 4: Install the post cap light

Connect the Post Cap Light lead wire to the extension wire, then install the light, taking care not to pinch the wires. You may need to gently tap the top of the light with your hand or a soft mallet to seat it snugly and flush with the post.

Connect the extension wire to the splitter. Coil any excess wire and secure it with a mounting cable tie, then secure any loose wire to the framing with insulated staples.

Install under-rail lights

Each Under-Rail Light run consists of two lights, with one installed on each side of the foot block at the center of the rail. The lead wire for each light is routed through the closest post under the bottom rail bracket. The channels that hold the lights in place need to be installed before the railing.

If the light strip needs to be cut to length, cut the end without the lead wire. Apply silicone inside one of the provided rubber caps and slide it over the cut end of the light strip before inserting the strip into the channel.

It can be helpful to power up the system after installing each light, making problems such as loose connections or damaged wires easier to track down.

Under-Rail Lights on Railings Attached to Aluminum Posts

Installing an Under-Rail Light on a railing attached to an aluminum post requires fishing an extension wire up through the hollow post before the railing is installed. The extension wire will later be connected to the light’s lead wire and used to pull it back through the post and down through the decking to the splitter. If you’re installing the last Under-Rail Light and don’t have an extra extension wire available, use a length of string or wire as a pull line instead.

Step 1: Drill a hole through the deck surface

When marking the holes for the aluminum post base fasteners, mark an additional hole in the center that aligns with the opening in the bottom of the post. Drill a 1/2-inch hole through the decking. If a joist or beam is directly beneath the hole, you may need to use a longer auger bit and angle the hole to one side.

Step 2: Drill a hole in the post

Mark the location of the bottom edge of the bottom rail bracket, then drill a 1/2-inch hole through the post just below the mark.

Step 3: Feed an extension wire through the post

Feed an extension wire up through the hole in the decking and through the hollow post. To pull the wire through the hole near the bottom rail bracket, pinch the ends of a cable tie together and push the center of the tie through the hole to create a loop. Feed the extension wire through the loop, then pull the cable tie back through the hole, bringing the extension wire with it.

Step 4: Install the light channel

Flip the assembled railing section upside down and install the light channel beneath the bottom rail using the provided screws. Center the channel between the post and foot block, cutting it to length if needed.

Step 5: Install the light strip

Push the light strip into the channel with the lead wire facing the post side.

Step 6: Make the connections

Once the railing is set in place, connect the lead wire to the extension wire, then use the extension wire to pull the lead wire through the post and deck to the splitter. Remove the extension wire if it isn’t needed to reach the splitter. Coil any excess wire and secure it with a mounting cable tie, then secure any loose wire to the framing with staples.

Under-Rail Lights on Railings Attached to Sleeved Wood Posts

When installing an Under-Rail Light on a railing attached to a sleeved wood post, route the lead wire through the Post Sleeve and decking as the sleeve is installed. The light channel is attached beneath the bottom rail before the railing is installed, while the light itself is installed in the channel after the railing is in place.

Step 1: Drill a hole through the deck surface

Drill a 1/2-inch hole through the decking as close to the post as possible. Locate the hole at the center of the post on the side facing the section of bottom rail where the light will be installed.

Step 2: Drill a hole in the post sleeve

Mark the location of the bottom edge of the bottom rail bracket, then drill a 1/2-inch hole through the Post Sleeve just below the mark.

Step 3: Feed the lead wire

Feed the lead wire attached to the Under-Rail Light through the hole in the side of the Post Sleeve and out the bottom. With the lead wire in place, slide the Post Sleeve down over the post and feed the wire through the hole in the decking before setting the sleeve onto the deck.

If the bottom of the Post Sleeve pinches the wire, enlarge the hole in the decking or notch the bottom of the sleeve enough to provide clearance. Keep the opening small enough that it will be concealed by the post skirt.

Step 4: Install the light channel

Flip the assembled railing section upside down and install the light channel beneath the bottom rail using the provided screws. Center the channel between the post and foot block, cutting it to length if needed.

Step 5: Install the light strip

After the railing is installed, push the light strip up into the channel.

Step 6: Make the connection

Connect the lead wire to the splitter. Coil any excess wire and secure it with a mounting cable tie, then secure any loose wire to the framing with staples.

Install deck stair lights

If possible, install the stair lights before the tread blocking, treads, and stringer fascia are installed. Leaving these components off provides easier access for routing and connecting the wires. The treads should have at least a 1/2-inch nosing to help protect the lights below.

It can be helpful to power up the system after installing each light, making problems such as loose connections or damaged wires easier to track down.

Oval Riser Lights

Each Oval Riser Light has two lead wires: One accepts power from the previous light or splitter, and the other connects to the next light. When Oval Riser Lights are installed on every step, they are designed to be daisy-chained, so you don’t need to run extension wires between the lights.

Drill the holes as straight through the risers as possible. If a hole is drilled at an angle, the light may not seat flat against the riser. Use a sharp Forstner bit to create a clean, accurately sized hole. A spade bit or dull Forstner bit can leave a rough or oversized hole. Because each light is held in place by friction, an oversized hole could allow it to come loose.

Step 1: Mark the holes

Position the lights near the top of the risers but locate each hole so the top of the light housing will sit just below the tread blocking.

Step 2: Drill the holes

Use a 1-inch Forstner bit to drill the holes through the risers.

Step 3: Install the lights

Orient each light horizontally with the fixture facing down, then push it into place or gently tap it with a soft rubber mallet. Make sure each fixture remains level as you install it.

Step 4: Make the connections

Connect the male connector on the first light to the splitter and its female connector to the male connector on the next light. Continue connecting the lights in this manner to the end of the run. Leave the protective cap on the unused connector of the last light in the series. Secure loose wires to the stringers or underside of the tread blocking.

Linear Riser Lights

Linear Riser Lights are easier to install before the tread blocking is in place, but they can also be installed after the blocking. Unlike Oval Riser Lights, Linear Riser Lights require Y-splitters to connect multiple lights in a run.

Step 1: Mark the riser holes

Position each light so it is centered on the riser. Mark the riser so the outside edge of the wire hole aligns with the outside edge of the light. Use the same spacing to mark the remaining risers.

Step 2: Drill the holes in the blocking (If Necessary)

If the tread blocking is already in place, drill a 1-inch hole through the top of the blocking at each light location to provide enough room to fish the lead wire through the riser and down below the blocking. If the treads and blocking are in place, use a long auger bit to angle a hole through and out the bottom of the blocking.

Step 3: Drill the riser holes

Drill a 1/2-inch hole through each riser, positioning it so the top of the hole is at or just below the top of the riser.

Step 4: Install the light brackets

If the treads are not yet installed, temporarily position a tread or scrap board with the proper overhang to help locate the brackets. Position each bracket with the prongs facing up and pressed tight against the underside of the tread, then secure the brackets to the riser with the screws provided.

Step 5: Install the lights

Feed each lead wire through the hole in the riser and down below the tread blocking, then snap the light onto the bracket.

Step 6: Make the connections

Use the Y-splitters to connect the first light to the main splitter and additional Y-splitters to connect each subsequent light to the next light in the run.

Hire a pro

If installing deck lighting seems beyond your DIY skills or comfort level, consider hiring a professional deck builder to handle the job. An experienced pro can help plan the layout and make sure everything is installed correctly.