In the world of LED lighting, dimming is an important feature to consider. Dimming allows you to adjust the light output of your LEDs, which can be useful for a variety of reasons. In this comprehensive guide, we will discuss all aspects of how to dim LED lights.
We will cover what is dimming with the different methods for dimming LED lights, how they work, as well as the various types of LED dimmers available on the market. So whether you are looking to install new LED lamps in your home or office, or want to know more about how to dim LEDs, this guide has you covered.
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Dimming is the method of reducing the output of light from an artificial lighting source. When a lighting fixture or bulb is dimmed, the lumen output of the light source is decreased, lowering the lighting levels in a room.
Dimming can be used for a variety of purposes, such as reducing energy consumption, creating different lighting effects, or extending the life of light bulbs. Dimming is commonly used with LEDs, as they are very efficient and can achieve a wide range of light outputs.
In lighting design, there are two main types of dimmed lighting: active dimming and passive dimming. Active is where the power to the light source is actively reduced and there are many ways of doing this, while passive relies on a material that absorbs light to reduce the output.
Dimming works by reducing the amount of power that is supplied to the light source. This can be done either by reducing the voltage or by reducing the duration of the power cycle. By doing this, the overall light output is reduced and the fixture appears to dim.
LED is now the primary source of lighting and it can be dimmed. However, dimming LED requires careful planning and there are a variety of types of LED to be aware of.
Most LEDs in use today are constant current or constant voltage and require a power supply called a ‘driver’ to convert the AC current from a lighting circuit into a low voltage DC current that is suitable for the type of LED chips being used in the fixture.
When dimming lighting, the driver has to be compatible with the control method being used in the room or building. There are a variety of methods which we will come onto below.
The driver is either incorporated internally in the product or you have to pair a suitable external driver with the LED fixture or series of fixtures being installed.
Many LEDs come with built-in drivers that allow them to be dimmed using one of the many methods available. To dim an LED with an internal driver, you will need a compatible dimmer switch, and be sure to check that it is indeed dimmable. Internal drivers cannot be accessed or replaced without potentially nullifying the warranty.
The reason internal dimmable LED drivers are used is to provide a space-saving and often more aesthetically pleasing solution, as well as reducing installation costs.
Lighting fixtures with internal dimmable drivers include:
If your LED does not have a built-in driver, you will need to use an external driver. External drivers are often used with high-voltage LEDs. To dim an LED with an external driver, you will need a compatible dimmer switch.
External dimmable drivers are used when an internal driver is not suitable or practical. They are also useful when upgrading older lighting to LED, or when installing new lighting in a large area where multiple fixtures will be used. External dimmable drivers offer more flexibility as they can be replaced if necessary, and are often easier to wire.
The reason external dimmable LED drivers are used is that they can be located away from the light source, often in a more convenient location. They are also easier to replace if they fail.
Lighting fixtures with external dimmable drivers include:
There are various ways to reduce power from reaching a light source and each of these methods have been adopted within interior and exterior lighting schemes.
Phase control is the most common type of dimming used with LEDs. It works by reducing the amount of time that the power is supplied to the light source. The duration of the power cycle is shortened, which reduces the overall light output.
There are two types of phase control dimming: leading edge and trailing edge. Leading-edge dimming reduces the power at the beginning of the cycle while trailing edge dimming reduces the power at the end of the cycle.
The most common type of phase control is leading-edge, which is often used with low-voltage LEDs. Trailing edge is often used with high-voltage LEDs and can result in a more abrupt dimming effect.
Leading-edge phase control dimming is similar to regular phase control dimming, but the power is reduced at the beginning of the cycle instead of the end. This can result in a smoother dimming effect and is often used with low-voltage LEDs.
What is Leading Edge Dimming?: Leading-edge dimmers have traditionally been more popular than trailing-edge dimmers. They have been around for a long time and are usually used to dim traditional incandescent and mains halogen light bulbs. This makes them better for higher wattage bulbs with capacities up to 1000W, but they can also work with LED light fixtures but rarely acceptably across the whole of the dimming curve.
Trailing edge phase control dimming is the opposite of leading-edge phase control dim. The power is reduced at the end of the cycle, which can result in a more abrupt dimming effect. This method is often used with high-voltage LEDs.
What is Trailing Edge Dimming? : Trailing edge dimmers existed before LEDs were a useful light source but particularly became popular in the age of LED as it’s a method of shortening the alternating current to the light source was proven to be more tolerant to the lighter loadings of LED.
0- to -volt dimming is a control method used mostly in architectural and commercial lighting. It sends a unipolar signal (two wires) from the controller to the driver, which then sets the power output to the light.
What is 0-10V Dimming?: 0-100V DC is passed through a resistor to create a voltage drop and dim the light. 0-100Vdc is a standard control signal in the lighting industry and was used to dim fluorescent lights. It can also be used with some low-voltage AC LEDs. The advantage of using 0-100V is that it can be easily transmitted over long distances using standard cabling. The disadvantage is that it can cause flickering at low dimming levels.
The one-to-ten volt dimming control system is commonly used in commercial lighting applications. It uses a pair of wires to send a dimming signal from the controller to the driver that is separate lighting power wires, which then sets the power output to the light.
What is 1-10V Dimming?: This is a very common control protocol that uses a single wire to send a control signal from the lighting controller to the dimmable driver. The voltage on the wire determines how much light is output by the fixture.
Pulse width modulation is a type of digital dimming that works by rapidly turning the light on and off. The speed at which the light is turned on and off determines how bright it appears to be.
What is PWM Dimming?: Pulse Width Modulation or PWM for short is a type of DC dimming. PWM dimming involves switching the power on and off very rapidly, which in turn will create the illusion that the light is dimming when it’s actually just being turned off and on really quickly.
PWM dimming is often used with LEDs because it doesn’t produce any electromagnetic interference (EMI) and helps to extend the life of the LED.
DALI is a digital protocol that is used to control lighting. It allows for the dimming of LEDs and other light sources using a variety of methods, such as 0-100%, trailing edge, and leading-edge dimming. DALI is also available in a variety of different voltages, including 110V, 220V, and 240V.
What is DALI Dimming?: Digital Addressable Lighting Interface (DALI) is a two-way digital communication protocol that allows lighting fixtures to be controlled and monitored individually or in groups. DALI is often used in commercial lighting applications, but it is also becoming more common in residential applications. DALI-compatible LED fixtures can be controlled with a variety of devices, including wall-mounted switches, occupancy sensors, and photosensors.
Some LED fixtures come with built-in dimmers. These are often 0-100% dimmers that can be used to dim the light output of the fixture. However, not all fixtures with built-in dimmers are compatible with all types of LEDs. It is important to check the compatibility of the fixture and the LED before purchasing.
What is Built-in Dimming? Built-in dimming is a feature that some LED light fixtures have where the dimmable function is built into the fixture. This means that there is no need for an external dimmer or controller.
Analog dimming is a type that uses an analog signal to control the light output, typically the 0-10V or 1-10V dimming methods.
There are two types of phase control dimmers: 0-100% and 100-0%. A 0-100% dimmer will reduce the power at the beginning of the cycle, while a 100-0% dimmer will reduce the power at the end of the cycle.
The most common type of phase control dimmer is 0-100%, which is often used with low-voltage LEDs. 100-0% dimmers are often used with high-voltage LEDs and can result in a more abrupt dimming effect.
Phase control dimmers are available in a variety of different voltages, including 110V, 220V, and 240V.
A leading edge phase control dimmer is a type of 0-100% dimmer that reduces the power at the beginning of the cycle. Leading edge phase control dimmers are often used with low-voltage LEDs and can result in a more gradual dimming effect.
A trailing edge phase control dimmer is a type of 100-0% dimmer that reduces the power at the end of the cycle. Trailing edge phase control dimmers are often used with high-voltage LEDs and can result in a more abrupt dimming effect.
Retractive switch dimming is a type of dimming that uses a physical switch to control the light output. Retractive switch dimmers are often used in residential applications and can be used with a variety of different light sources, including LEDs, incandescent, and halogen bulbs.
Push to dim is a type of dimming that uses a physical button to control the light output. A depress of the button cycles through the dimming levels, while a hold of the button turns the light off.
Push to dim is often used in residential applications and can be used with a variety of different light sources, including LEDs, incandescent, and halogen bulbs.
A rotary dimmer is a style of dimmer that uses a physical knob to control the light output. Rotary dimmers will utilise 1-10V, trailing-edge or leading-edge protocols.
A slide dimmer is a type of dimming that uses a physical slider to control the light output and use a variety of protocols.
Andrew Orange , the owner of Orange Lighting qualified and worked as an interior designer in 1993 before specialising in lighting working on high profile projects based in London. Since starting Orange Lighting Ltd in 2003 he has been sharing his knowledge and unique teaching style mostly to his designer clients, offering practical real life advice born from running a busy consultancy and lighting supply business. Launching in 2020, his blog has evolved into Quick & Easy Lighting, curating some 25 years design experience into making the lighting choice and design process achievable and easy to understand for all.