In low-voltage LED systems (like 12V or 24V strips), wire thickness is just as important as choosing the right driver. Get it wrong, and you'll see flickering, dimming, or even melted cables.
⚠️ The Problem: Voltage Drop
Low-voltage systems suffer from voltage drop across long cable runs — especially if the wire is too thin. In fact, all electrical circuits experience voltage drop since it is related to the current flow, but in low-voltage installations the voltage loss is much greater proportionally compared to the PSU voltage and therefore noticeable and important.
Example: A 5A load over 10 meters using 18AWG wire can drop over 3V — enough to dim LEDs or cause uneven lighting.
In a 120VAC system, a 3V drop is only 2.5% which is negligible. But in a 24V installation, the 3V loss equates to 12.5% of the nominal voltage which will affect your light output. And in a 12V installation, the 3V drop becomes a whopping 25% loss compared to the driver voltage.
🔧 Rule of Thumb: The 3% Rule
You should never allow more than 3% voltage drop from your power supply to your LED load.
📊 Use Our Wire Sizing Chart
This table helps you select the correct wire gauge (AWG) based on voltage, current, and run length:
| Voltage | Current | Distance (ft) | Recommended Wire Gauge |
|---|---|---|---|
| 24V | 5A | 20 ft | 14 AWG |
| 24V | 3A | 10 ft | 16 AWG |
| 12V | 5A | 15 ft | 12 AWG |
| 12V | 2A | 10 ft | 16 AWG |
(Based on 3% drop target using copper wire. Always round up for safety.)
🚫 Common Mistakes
- Using the same gauge on both AC and DC sides of the PSU
- Underestimating run length — remember, distance = one-way × 2!
- Daisy-chaining strips instead of parallel feeding
✅ Best Practices
- Always use thicker wire on the DC side of your power supply
- Feed longer LED runs from both ends to avoid brightness fade
- Use Wago 221 connectors for clean, safe joins (no screw terminals)
- Test full voltage at the end of your run under load
💡 Real Example
You’re powering a 4.8W/m 24V strip at 5m (24W total). That’s ~1A. With 10ft of cable from driver to strip, you can safely use 18AWG — but 16AWG gives you headroom.
Need Help Choosing Wire?
Check out our pre-cut low-voltage wiring kits or use our live chat to ask for custom sizing help based on your run length and wattage.
🧰 Recommended Wiring Accessories
For a clean, safe, and professional install, we recommend using our tested range of LED wiring accessories:
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✅ Wago 221 lever connectors (no screw terminals)
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✅ Gel-filled waterproof wire nuts for outdoor runs
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✅ Terminal blocks, splitters, cable clips, and ferrules
These are the same components used by our installers daily. They’re safe, code-compliant, and easy to use.
🔗 Browse LED Wiring Accessories →
Next up → Part 3 – The Truth About Connectors
