Micro-LEDs are one of the most effective ways to bring a model railway layout to life. Tiny enough to hide inside a signal box window or beneath a platform canopy, they add warmth, realism and atmosphere that no other detail can match. This step-by-step guide explains exactly how to install micro-LEDs on a model railway layout, whether you're lighting a single building or wiring an entire station scene.

What You'll Need

• Micro-LEDs (pre-wired with resistors are easiest for beginners)
• A suitable power supply (3V or 12V depending on your LEDs)
• Fine wire (0.1mm enamelled wire works well for tight spaces)
• Resistors (if your LEDs are not pre-wired with them)
• A small drill or pin vice
• Superglue or PVA
• Black paint or electrical tape (to block light bleed)
• Multimeter (optional but useful)

At Model Railway Scenes, our micro-LEDs come pre-soldered with resistors for 8–12V supplies, making them straightforward to connect without additional components.

Step 1: Plan Your Lighting Before You Build

The easiest time to install micro-LEDs is before a building or scenic feature is fully assembled. If you're working on an existing layout, plan your cable routes carefully to avoid visible wiring.

Decide:

• Which buildings, structures or features you want to light
• Where your power supply will be located (usually beneath the baseboard)
• How you'll route wires — through the baseboard, along the back of a scenic backdrop, or hidden beneath ground cover

Sketching a simple wiring diagram saves a lot of frustration later, especially if you're lighting multiple buildings from a single supply.

Step 2: Choose the Right Micro-LEDs

Micro-LEDs are available in several colours, each suited to different effects:

• Warm white — ideal for interior lighting in cottages, signal boxes and station buildings; mimics incandescent bulbs
• Cool white — suits modern buildings, platform canopies and fluorescent-style lighting
• Yellow — perfect for street lamps, gas lighting and older station lanterns
• Red and green — signals, indicator lights and level crossing lamps

For most heritage British layouts, warm white is the most versatile choice.

Step 3: Drill the Mounting Hole

Use a pin vice or small drill to create a hole just large enough for the LED body — typically 1–2mm. Common locations include:

• Ceiling of a building interior (drill down through the roof)
• Inside a lamp post or street light
• Behind a window opening
• Beneath a platform canopy
• Inside a tunnel mouth

Work slowly and test-fit the LED before applying any adhesive. A snug fit holds the LED in place without glue, but a small drop of superglue will secure it permanently.

Step 4: Route the Wires

Feed the LED wires through the hole and route them to your power supply. Tips for keeping wiring tidy:

• Drill a small hole through the baseboard directly beneath each building so wires drop cleanly out of sight
• Use enamelled wire for very tight runs — it's thin enough to hide under scatter or along the base of a wall
• Paint exposed wire with dark brown or black paint to blend with the scenery
• Bundle multiple wires together with a small cable tie beneath the baseboard

Step 5: Understand Resistors and Voltage

LEDs require a resistor to limit current and prevent burnout. The resistor value depends on your supply voltage and the LED's forward voltage.

If you're using our pre-wired micro-LEDs with built-in resistors, simply connect them to an 8–12V DC supply and they're ready to go. No calculations needed.

If you're using bare LEDs, the formula is:

Resistor (ohms) = (Supply voltage − LED forward voltage) ÷ LED current

For a 12V supply with a standard white LED (3.2V forward voltage, 20mA current):
(12 − 3.2) ÷ 0.02 = 440 ohms — use the nearest standard value of 470 ohms.

When in doubt, use a higher resistance value. A slightly dimmer LED is far better than a burnt-out one.

Step 6: Connect to Your Power Supply

Micro-LEDs are polarity sensitive — they only work when connected the correct way round. The longer leg (anode) connects to positive, the shorter leg (cathode) to negative.

If your LED doesn't light up, simply reverse the connections. There's no risk of damage from a brief incorrect connection.

For multiple LEDs from a single supply, wire them in parallel (positive to positive, negative to negative) rather than in series. This ensures each LED receives the full supply voltage and allows you to add or remove individual lights without affecting the rest.

Step 7: Test Before You Fix Everything Down

Always test your LEDs before sealing buildings shut or applying ground cover over wiring. Connect to your power supply and check:

• All LEDs light up at the expected brightness
• No light bleed through walls or roofs (paint interior surfaces matt black if needed)
• Wires are not under tension and won't pull free

Once you're happy, secure the building in place and apply scenic materials over any visible wiring.

Step 8: Reduce Light Bleed

Light bleed — where light escapes through walls, roofs or floors rather than just windows — is the most common problem with model railway lighting. Fix it by:

• Painting interior walls and ceilings with matt black paint before assembly
• Lining roofs with black card or foam
• Sealing gaps around window openings with a small amount of black paint or PVA

A well-blacked interior makes the lit windows glow convincingly rather than the whole building appearing to shine.

Step 9: Add Switching or Dimming (Optional)

For more control over your lighting, consider adding:

• A simple on/off switch — lets you turn lighting zones on independently
• A PWM dimmer module — allows you to adjust brightness, useful for creating a dusk effect
• A DCC accessory decoder — if you run a DCC layout, you can control lighting via your controller

Common Mistakes to Avoid

Skipping the resistor

Running an LED without a resistor will burn it out almost immediately. Always use the correct resistor or buy pre-wired LEDs.

Wiring in series instead of parallel

LEDs wired in series share the supply voltage between them, making each one dimmer. Wire in parallel for consistent brightness.

Not blacking out interiors

Light bleed ruins the effect. A few minutes with matt black paint before assembly saves a lot of frustration later.

Using too-bright LEDs

At OO scale, a little light goes a long way. If your LEDs are too bright, increase the resistor value to dim them down.

Frequently Asked Questions

What voltage do micro-LEDs need for a model railway?

Most micro-LEDs run on 3V or 12V depending on whether they include a built-in resistor. Our pre-wired micro-LEDs are designed for 8–12V DC supplies, making them compatible with most model railway controllers.

Do I need to solder micro-LEDs?

Not necessarily. Pre-wired micro-LEDs come with leads long enough to connect directly to a power supply using crocodile clips or a terminal block. Soldering gives a more permanent connection but isn't essential for getting started.

Can I use micro-LEDs with a DCC layout?

Yes. Connect them to a dedicated accessory power bus or use a DCC accessory decoder for individual control. Avoid connecting directly to the track bus as DCC voltage can fluctuate.

How do I stop light showing through the walls of a building?

Paint all interior surfaces with matt black paint before assembly. This absorbs stray light and ensures it only escapes through windows and doors.

How many micro-LEDs can I run from one power supply?

This depends on your supply's current rating. A 1A supply at 12V can comfortably run dozens of micro-LEDs simultaneously, as each typically draws only 10–20mA.

Ready to Light Up Your Layout?

Micro-LEDs transform a model railway from a static display into a living scene. Once you've lit your first building, it's hard to stop. Start with a single station building or signal box, get comfortable with the process, then work outward across your layout.

Explore our full range of model railway lighting, including pre-wired micro-LEDs with resistors, ready to connect straight to your layout.

Shop Micro-LEDs at Model Railway Scenes →