A Transformer for LED Strip Lights: An Ideal Guide

You may be wondering what the need for a transformer for LED strip lights is.

Shouldn’t we directly connect the LEDs to a power source and illuminate our homes?

Well, LED transformers are crucial components of AC electrical systems, without which the result is a failure. 

Moreover, you need to know the specific transformer that suits your LED strip lights.

In today’s article, we delve into the world of LED transformers and why they are essential. 

What’s a Transformer

A high-voltage transformer in a power substation

(A high-voltage transformer in a power substation)

A transformer is an electrical inductive machine that transfers alternating current (AC) electrical power from a single to multiple circuits.

Usually, transformers maintain a constant frequency while stepping up or down voltages. 

For example, to minimize electrical power losses, we transmit AC power at higher voltages to reduce electrical power losses while keeping the current low.

That’s a process known as stepping up using a step-up transformer.

We use a step-down transformer when stepping down voltages to usable levels like 110V, 220V, or 240V. 

Types of LED Transformers

Generally, LED transformers work under certain situations, making one suitable for an application and not the other.

Here we are looking at the two LED transformers.

Constant Voltage Transformers (CVTs)

CVTs provide a constant voltage output like 12V or 24V to LED systems.

Consequently, they are popular for lighting systems needing consistent brightness.

Moreover, we use them in low-voltage applications like powering LED strips or bulbs to extend their lifespans.

Constant Current Transformers (CCTs)

CCTs provide consistent current output to LED lighting systems while the voltage ranges depending on the wattage.

We use them to power heavy-duty LED systems like high-brightness LED arrays which change brightness with a voltage change. 

Keeping the current constant maintains the brightness at a given voltage, preventing damage due to electrical current fluctuations. 

Choosing the Right Transformer for Your LED Strip Lights

An LED strip connecting to a power adapter

(An LED strip connecting to a power adapter)

Most LED systems use a single type of transformer since they execute a certain brightness level.

However, some lighting systems combine CVTs and CCTs, making them more versatile and valuable for large-scale lighting operations.

Let’s consider what you must consider picking the suitable transformer for your LED strip lights. 


Before settling on a transformer, consider if your LED system requires a constant voltage or current.

Traditional power supply units usually deliver a constant voltage which could be better for lighting. 

The reason is that LEDs are current-driven devices, and the chances of overdriving them are high when providing constant voltage.

Therefore, if you need a constant brightness, keep the current constant, and you will have a consistent brightness throughout the strip. 


If you’re installing 12V LED strips, match them with 12V transformers.

Similarly, match 24V transformers with 24V LED strips.

If you fail to do so, you may end up underpowering or overpowering your LEDs, leading to less brightness or damage.

Series or Parallel Lighting

LED lights illuminating a modern transport warehouse

(LED lights illuminating a modern transport warehouse)

If you are connecting your LEDs in series, we recommend using constant current transformers (CCTs).

From physics, the electrical current through devices connected in series is constant while voltage drops due to circuit impedances. 

Now if you use CVTs for parallel lighting, there will be massive fluctuations in the brightness levels of your LED lighting system.

The reason is that keeping the voltage constant means the electrical current through the series LED connection fluctuates. 

And, as the current through all LEDs is constant, you will notice that all lights dim and brighten up uniformly if it fluctuates. 

Dimming Compatibility

When planning to install LEDs with dimming capabilities, ensure that your transformer is compatible with the method you will use.

Typically, transformers can have or lack built-in dimming capabilities. 

And we don’t recommend using a dimmer with a transformer with dimming capabilities as such would be redundant. 

Power Capacity

Transformers have different power capacities that should match the power consumption of the LED strips.

Typically, we measure power consumption in watts per meter (W/m), and you can find your LED strip’s rating in the product specification. 

To get your transformer’s power capacity, multiply the LED’s W/m by the strip’s total length in meters. 

Difference Between a LED Transformer and a Driver

A LED driver

(A LED driver)

Sometimes, people use the terms LED transformers and drivers interchangeably.

The reason is that, to some degree, they play the same role hence the confusion.

But they are not one device, and they differ in construction. 

LED Transformers

Transformers convert the same voltages from one level to another.

For example, they transform 120V AC from the mains to 12V AC that the LED strips can use.

As you can see, the power remains as alternating current (AC), and they are popular in powering low-voltage LEDs.

LED Drivers

On the other hand, LED Drivers take AC power and convert it to DC power that an LED strip can use.

Generally, we refer to them as adapters, and they are common in all cables for charging our electronics like laptops and phones. 

They are important when supplying a constant voltage or current to an LED strip.

AS transformers supply a constant voltage, people often confuse them with constant voltage LED drives.  


Why do LED transformers fail?

LED transformers fail for several reasons.

First, they fail due to overloading or connecting too many LED strips more than they can handle.

Transformers have a specific maximum load capacity that they can handle, beyond which they overheat and fail. 

Second, subjecting a transformer to fluctuating incoming voltages or power spikes damage the coils leading to failure.

Thirdly, cheap transformers fail due to poor quality and manufacturing defects. 

For instance, cheap windings may fail to produce sufficient magnetic flux leading to reliability issues.

What happens if you overload a LED?

Overloading an LED is terrible as it may lead to excessive current flow.

As electrical components, they have a maximum current that they can allow to pass through.

Therefore, any additional electrical current reduces lifespan and performance and causes fading.

What are the signs of transformer failure?

The first sign of a transformer failure is if you can’t detect any electrical current flow from the secondary terminals.

In other words, power flows in through the primary terminals, but non gets out. 

Second, unusual humming or buzzing sounds indicate loose core laminations or windings.

Third, look for flickering or dimming lights as they indicate an unstable voltage output from the transformer’s secondary terminal. 

Fourth, if your transformer has inbuilt protection mechanisms, check if they constantly trip, even with a bit of LED load. 

How many LED lights can I put on a transformer?

The number of LEDs you can put on a transformer depends on capacity.

You can add more LEDs than a smaller transformer if it is big.

Furthermore, consider the transformer’s load capacity to prevent overheating and potential failure. 

Third, consider the voltage drops of the wiring or connectors.

The reason is the longer the LED strip, the higher the resistance. 


Transformers are essential in all our industries, homes, automobiles, or any system that relies on electrical power.

And remember, the only thing a transformer can step up or down is the voltage.

You can’t use a transformer to step-up low to high power as power remains constant from the source. 

For example, you can choose a 24V or 12V transformer when powering your LED strips.

If you get power from a single source, the former will have a lesser electrical current due to a higher voltage. Power equals the product of voltage and current.