How to choose a power supply for LED strips?
Imagine this situation: you buy an LED strip for your living room, furniture backlighting, or a striking façade. Installation goes smoothly, and the first start-up is successful too, but after a while it turns out that the ends of the strip shine less brightly, the power supply heats up worryingly, and the whole lighting setup does not look as you planned. This is a scenario that happens surprisingly often, and in most cases the culprit is an incorrectly selected power supply.
In this article, we explain step by step how to choose the right power supply for an LED strip so that your installation operates reliably, safely, and for many years.
Data
4 September 2025
You will read in
6 Minutes
Subject
Power supply for LED strips
Why is the choice of power supply so important?
The power supply is the heart of the entire LED installation. It is responsible not only for whether the strip shines at full power but also for its longevity and operational stability. An improperly selected power supply can cause flickering, dimming, or overheating of the diodes. A good power supply guarantees even and reliable illuminance.
Key parameters of LED tape
The first step in selecting a power supply is to check the basic parameters of the tape. The three most important pieces of information are: supply voltage, power consumption per metre, and the maximum length of the section that can be powered from one end. Commonly used voltages are 5, 12, and 24 volts. The power is specified per metre of tape and depends on the density and type of diodes. It's also important to note whether the tape is classic (constant voltage) or digital, where each diode is controlled individually.
How to calculate the power of the power supply?
Once we know the power and length of the tape, we can calculate how much energy the entire installation will consume. Let's assume the tape consumes approximately 9 W per metre, and we plan to have seven metres of lighting. This results in a total requirement of about 67 W. To this value, it is advisable to add a buffer, ideally 20–30 percent, so the power supply doesn't operate at its maximum capacity. In this case, that means around 87 W, so the best choice would be a 12 V power supply with a capacity of 100 W. This ensures the device remains cool, stable, and reliable.
Why are cables so important?
Just as important as power is the current, or the amperage, drawn by the tape. It determines the thickness of the wires that should be used. Wires that are too thin cause voltage drops, which result in the tape ends glowing weaker. The lower the supply voltage, the more problematic such losses are, which is why particular attention should be paid to five-volt and twelve-volt tapes. In practice, the best solution for longer sections is to power them from both ends or introduce additional power points every few metres. In large installations, it's also advisable to use separate fuses for each branch.
How to choose the type of power supply?
When selecting a power supply, not only power and voltage matter but also its construction and purpose. For interior use, open power supplies in IP20 class are commonly used; these require ventilation and installation in a dry place. In damp environments and outdoors, hermetically sealed models with IP65 or IP67 are essential. In simple installations, adapter-style power supplies or plug-in versions are sufficient. In professional systems, it's advisable to opt for devices with active power factor correction, protections, and the capability to work with dimming controllers, for example, in DALI, 0–10 V, or PWM standards.
Digital strips - what to look out for?
A separate issue concerns digital LED strips. Here, it's not just about the length but also the number of LEDs, as each can draw up to 60 milliamps. This means that a five-meter section with three hundred LEDs may require up to eighteen amperes, necessitating a powerful five-volt power supply with a capacity of over 100 W. In this case, it's absolutely essential not to rely solely on power from one end. Additional power points, filtering capacitors, and protections for individual sections are necessary.
Quick checklist for the installer
To make things easier, we have prepared a short list of rules worth remembering for every LED installation:
The power supply must operate at the same voltage as the strip.
Its power rating should be at least 20–30% higher than the strip’s total power consumption.
The cable cross-section should be selected so that the voltage drop does not exceed 3%.
Longer strip runs are best powered from both ends.
The type of power supply should be matched to the operating conditions, including IP rating, dimming capability, and power factor correction.
Every installation should be protected with fuses, and the power supply must have adequate ventilation.
Summary
Selecting a power supply for an LED strip is not only a matter of maths, but also of understanding practical installation principles. A properly selected power supply should have an output at least twenty per cent higher than the strip’s power demand, operate at the same voltage as the strip, be matched to environmental conditions, and be suitable for the intended control method. It should also work with cables of an appropriate cross-section to avoid voltage drops and uneven light output.
If you want to avoid problems with flickering, overheating, and failures, choose proven power supplies equipped with appropriate protection features and selected for the specific type of LED strip. Contact us – we will advise you and select a solution perfectly tailored to your project. This ensures your LED installation will provide uniform, reliable light for many years.
