How to choose the right LED transformer: 5 mistakes to avoid
Choosing the correct LED transformer is essential to ensure maximum efficiency, durability and safety of your lighting system. In this how-to guide, you'll find out how to avoid the 5 most common mistakes professionals encounter when selecting an LED power supply.
🔌 What is an LED transformer and what is it used for
In common parlance, LED transformer is often referred to, but it is important to distinguish between:
- Transformer: lowers the voltage (e.g. from 230V to 12V or 24V), but does not regulate the current. Trasformatore: abbassa la tensione (es. da 230V a 12V o 24V), ma non regola la corrente.
- LED power supply (or LED driver): delivers a constant current or voltage, protecting the system.
The 5 most common errors when choosing the LED transformer
1. Miscalculate the power of the power supply
The connected LED load is often underestimated. Choosing an undersized power supply leads to overheating and premature failure.
👉 Tip: Always add a safety margin of 20-30% compared to the power required.
2. Mistake between constant voltage and current
Different LEDs require different power supplies:
- Constant voltage (12V or 24V): e.g. LED strip
- Constant current (e.g. 350mA, 700mA): e.g. COB modules, or circuits without on-board electronics.
👉 Check the LED load data sheet before purchasing.
3. Ignore the installation environment
Not all transformers are suitable for humid, dusty or temperature-hanging environments.
👉 Choose according to the degree of protection:
- IP20: dry environments
- IP65 or higher: outdoor or humid environments
And make sure you comply with thermal dissipation conditions.

4. Do not check compatibility with the dimmer
If you want to adjust the brightness, make sure the LED transformer is dimmable and compatible with the system used (DALI, 0-10V, Triac, PWM...).
👉 Using an incompatible transformer causes flicker or component damage.
5. Purchase uncertified products
A poor quality LED power supply can cause short circuits, blackouts or efficiency losses.
👉 Always check for the presence of:
- CE, RoHS certificates
- Overvoltage and overheating protections
ENEC or TUV standards, if required
Choosing the most suitable LED transformer for your system means avoiding flickering, short circuits and technical problems that can compromise the entire system.
Knowing which mistakes to avoid allows you to work safely, respecting regulations and optimizing your investment over time.
For over 20 years, Tector has been the point of reference for lighting professionals. contact us now for a consultation!