How to power a LED strip?

LED strips allow you to quickly and effectively use the handiness of LED technology.

They are usually sold in rolls of 5 meters and consist of modules of 3, 5, or 10 centimeters in length.

The LED strips’ normal is 12 or 24 volts (depending on the model chosen). With the different connections, it is essential to pay attention to the polarity of the current.

Since LEDs are diodes that allow current to pass only in one “direction,” it is good to pay attention to the negative cable (usually black or brown) and the positive line (typically red or blue). Any faults in the connection between the power supply and the LED strip could affect its life and efficiency. This is due to the low ability to support reverse voltage when the current flows with a polarization opposite to regular operation.

How to choose the right LED strip?

The number of LEDs on the meter directly affects the brightness delivered by the LED strips and their consumption. Depending on the desired lighting goal, you will need to use one type of strip or another. Next, we will show a rule to correctly select the strip that best suits your needs, depending on the LEDs/meter that the strip has.

– 30 LEDs/meter: Personal lighting. Used to highlight selected elements in a dim way.

– 60 LEDs/meter: used for standard lighting. Used for integration in ledges, bars.

– 120 LED/meter: For high lighting requirements. They are widely used for signage, outdoor lighting.

Strip types according to the kind of LEDs

To elaborate a little more on the chips that LED strips to use, we will explain in more detail the most common chips on the market and their main uses.

– SMD Strip 3528/2835 This chip is used for low power and low consumption strips. Since they have low consumption, they are usually used in installations where the light needed is decorative. They are single-color strips and the cheapest option.

– SMD strips 5050 This type of LED strips has higher consumption and provides more power than the 3528 SMD. They are used for installations where the lighting requirements are higher than for purely professional lighting. They are monochromatic and multicolor (RGB) strips.

– 3014 SMD strips This type of strips is used more when the purpose is decorative. They have a higher density of LEDs on the strip, so the lighting it provides is high intensity and continuous. They are low power consumption strips but with exceptional light output.

– SMD 5630 strips: This type of strip provides a more significant amount of light with the same consumption as SMD 5050 strips. This type of strip is used for installations where high light output is required. These strips are monochromatic and are used in professional facilities where high power is needed.

Installation of LED strips

The most commonly used LEDs in strips

LED strips are strips that have the adhesive layer for mounting on one side and connection pads, bus bars, resistors, and LEDs on the other.

The “heart” of the strip is the surface mount LED (SMD) light, which directly affects the output of the whole strip.

Not all strips are the same: it is possible to find strips on the market that are based on outdated LEDs and therefore have much lower brightness than those based on newer LEDs; here is a list of the most common LEDs in use today:

Usually, the type of LED used is indicated on the package or by the seller (even online), but you can visually distinguish these three sizes:

In any case, I recommend choosing strips based on LED 5630/5730 or higher.

If using for diffused light with no special brightness requirements, you can also use the less powerful 5050, but only if the cost justifies it.

I would avoid buying strips based on even more modest LEDs like 3528 or earlier.

How do RGB products work?

RGB products are built with red, green, and blue LEDs placed on the same chip in some cases and on three separate chips in others. Thanks to this configuration, it is possible to create color mixes that control the power in each color, obtaining a wide range of colors.

Primary colors: red (R), green (G), and blue (B).

Secondary colors: Yellow, Pink, Turquoise Blue, Orange, Purple, and “White.”

Primary colors are those provided by every RGB product we have in the catalog. Secondary colors are obtained from mixing primary colors. To achieve this effect, you need a controller.

The wavelengths of the colors are as follows:

Red: 625-740 nm

Orange: 590-625 nm

Yellow: 565-590 nm

Green: 500-565 nm

Cyan: 485-500 nm

Blue: 440-485 nm

Violet: 380-440 nm

LED Power Supply

Choosing the suitable power supply for STRIP LED is very important to ensure a proper and long-lasting installation. Let’s analyze in detail some essential characteristics that apply to our LED system.

Type: check what kind of power supply you are using. The most common ones are toroidal, electronic, and switching. The latter is recommended for flexible LED strips because they have a smaller footprint and higher efficiency than others.

Power: It is a good practice to use power supplies with a power rating of at least 10-15% of the total input of the LED strip.

Voltage: Determine if the strips are operating at a constant voltage of 12 or 24 volts to select the power supply with the correct voltage.

Protection class: It is essential to select the correct IP rating for both the flexible LED strips and the power supplies. Usually, power supplies for LED strips are divided into IP20 for indoor and IP67 for outdoor.

Voltage drop: If you make an electrical connection with 10m or more LED strips, it is necessary to adjust the voltage drop by the corresponding regulator in the power supply (if the model allows it).

Efficiency: Check the efficiency, i.e., the ratio expressed in percentage between the power consumed and the power available at the output. A good power supply has a value of more than 80%.

300-12 slim power supply CL

Power supply for LED strips

How to calculate the correct voltage supply?


It would help if you supplied a 2 m long LED strip with a power of 14.4 W/m. Which power supply is more suitable?

Multiply the power/m x length (expressed in meters) of the light strip, i.e.: 14.4W/m x 2m = 28.8 W.

The correct power supply should be 35 W (which is 20% more than the power consumption of the LED strip).


If the power supply does not specify the power in watts, it is sufficient to multiply the power expressed in A by the output voltage. (Example 2A x 12v = 24 W)

To connect LEDs to the transformer.

If you bought an LED strip without a power supply, to connect it to the power, you would need a transformer, which is a device that allows you to convert an AC voltage (the 220V of the electrical systems of the house) into a constant voltage necessary to power the LED strips.

Several types of power supply differ in power (expressed in watts), voltage (expressed in volts), type (for example, transformers for indoor and outdoor), and for connection to the mains (some transformers do not have grounding).

It has been clarified that for the power supply of an LED strip, an indoor transformer is sufficient (cheaper than outdoor transformers), which corresponds to the characteristics of the LED strip to be supplied. So if the purchased strip has 12 V or 24 V, you need to make sure that the transformer’s voltage is the same.

You also need to make sure that the transformer is capable of supplying all the power consumed by the LED strip: For example, if the specifications of the strip state a capacity of 18 W, you must use a transformer with more than 18 W (e.g., 60 W, 75 W, 120 W, etc.). Note that it may connect multiple LED strips or even other devices to one transformer, so the LED power supply must supply the power required by all connected devices.

After selecting and purchasing the suitable transformer to power your LED strip, you can plug it in. First, disconnect the power from the main generator of the house, and then disconnect the existing terminals. 

After that, take the electrical cable that you have previously obtained from the house installation and connect the wires regarding the incoming phase (usually the brown or red line) and the neutral (usually the blue cable) to the L and N inputs of the transformer. Then connect the cable for grounding (usually the yellow and the green cable) to the corresponding input of the transformer indicated by the symbol with the three horizontal lines and the vertical line, and tighten all the terminals of the cables just connected.


At this point, take your LED strip, connect the positive wire (the red one) to the V+ input of the transformer and the negative wire (the black one) to the V- input, tighten the terminals again.

For this reason, I recommend that you carefully follow the wiring diagrams in the instruction manual that comes with the LED strip or rely on a professional.

Quality and reliability aspects, installation tips

It ‘should be noted that most of the LED strips available online are characterized by a medium-low quality, and therefore are not always reliable.

It is better to try to direct the choice to branded products or sellers with more excellent reliability both for the data and for the information on the type of LED.

It is better to avoid generic strips and choose strips that indicate the LED format (better 5630/5730) and brand (Cree, Epistar, etc.).

There are also much more reliable (and expensive) strips because they have integrated circuits on board that allow more accurate polarization.

Strip reliability is related to heat dissipation; another index of quality is the adhesive used on the strip, such as the 3M adhesive in the ribbon shown in the picture.

For good heat dissipation, LED strips should also not be placed on heat-insulating materials such as wood or plastic. Still, it is appropriate to glue them (after thoroughly degreasing the surface) into suitable aluminum profiles, providing protection, improving aesthetics, and acting as radiators.

The plastic cover of these profiles can be transparent or opaque (frosted); the latter somewhat reduces the glare, but of course, the light output.

Waterproof LED strips have a silicone coating on the LED side; I recommend using these only when necessary (humid environments), as the silicone coating degrades both heat dissipation and brightness somewhat.

The drivers used to power the strips will affect the reliability and quality of the emitted light. Still, unless you have special requirements, it is sufficient to buy a generic power supply with the correct output voltage capable of delivering the power absorbed by the LEDs.

For special requirements (for example, to avoid flickering phenomena in videos), you can use professional drivers or other solutions, as explained in this discussion:

3d on strips


I hope that the simple information in this article can help the less experienced to evaluate the purchase and proper use of LED strips.

As a rule, with these devices are realized special lighting, aesthetically pleasing, and not the main lighting of an important room. There are LED lamps with superior efficiency and performance.


Ena Leung

Ena Leung

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