When it comes to planning and installing LED lighting - especially for strip lights, linear runs, or architectural installations - voltage drop is one of the most overlooked but important electrical factors. Not properly planning your installation can lead to dim lighting, inconsistent brightness, or even premature failure. But what is voltage drop, and why does it matter in LED lighting systems?
What Is Voltage Drop?
Voltage drop refers to the reduction in voltage as electrical current travels through a wire. All wires have electrical resistance, and the longer the wire (or the higher the current), the more resistance the electricity encounters. This results in a drop in voltage between the power source and the end of the line.
In LED lighting, this voltage drop can become visible: the lights farthest from the power source may appear noticeably dimmer or can take on a different color temperature.
What Causes Voltage Drop in LED Systems?
Several key factors can contribute to voltage drop:
- Wire Length - The longer the wire run, the more resistance it introduces, and the more voltage gets lost along the way.
- Wire Gauge - Thinner wires have higher resistance. If you're using a wire that’s too small for the current it’s carrying, you’ll see more voltage drop.
- Total Load - The more LEDs (or power draw) on the line, the more current flows through the wire, increasing resistance and drop.
- Power Supply Distance - If your driver or transformer is too far from the lighting installation, the voltage drop can occur before the light even begins.
- Voltage Type - Systems operating at 12V DC experience more voltage drop over distance than 24V DC systems, simply because the lower voltage requires more current for the same wattage.
How to Measure Voltage Drop
To calculate or test the voltage drop in your LED system:
1. Use a Multimeter Tool
- Turn on your LED system
- Measure voltage directly at the power supply output (this should match your rated output - ex: 24V)
- Measure again at the end of the LED strip run
- The difference between these two values is your voltage drop
Example:
Power supply output = 24.0V
Voltage at end of strip = 22.4V
Voltage drop = 1.6V
2. Use a Voltage Drop Calculator
To save time and avoid guesswork, use our Voltage Drop Calculator to plug in your wire length, wire gauge, and total wattage. We offer a handy calculator on our site for this very purpose.
What Are the Effects of Voltage Drop?
- Dim or uneven lighting (especially at the far end of a strip)
- Color shifting (white light turns yellowish or blueish)
- Reduced lifespan of LEDs and drivers/transformers
- Failure to meet design or safety needs
How to Prevent or Fix Voltage Drop
- Use 24V instead of 12V - Higher voltage systems carry lower current, reducing drop over the same wire length.
- Shorten wire runs - Place the power supply closer to the lights.
- Use thicker wire - Upgrade to a lower gauge wire (ex: 14 AWG instead of 18 AWG).
- Use multiple power starter points - Instead of one long run, power your LED strips from both ends or at intervals.
- Split the load - Use parallel wiring for multiple sections rather than one continuous daisy chain.
- Add a dedicated voltage regulator - This can help keep output consistent if other options aren't feasible.
Lumilum Is Here To Help
At Lumilum, our team works to ensure your LED installations are energy-efficient and look stunning from end to end. Whether you're lighting a hotel lobby, gallery, or outdoor signage, we can help spec the right system, without voltage drop headaches.
Need help planning or pricing materials for your next LED project? Reach out today!