Leading Vs. Trailing Edge Dimmer – Which Is Best For LEDs?

What Is a Leading Edge Dimmer?

Leading edge dimmers are traditional dimmers designed for incandescent and halogen bulbs. These dimmers use a TRIAC to control the current that cuts the “leading edge” of the sine wave in the AC cycle. As a result, the dimmer delays the start of the electrical current flow and thus dims the lights.

Leading edge dimmer is one of the oldest dimming technologies. You may face buzzing noise issues while using these dimmers. Compared to modern dimmers, they generate more heat and are not an energy-efficient solution. Besides, you can’t integrate them with smart home technology.

Note: Leading edge dimmer can work with some dimmable LEDs and CFLs but doesn’t support all types.

Pros & Cons Of Leading Edge Dimmer

What Is a Trailing Edge Dimmer?

In the trailing edge dimmer, the brightness of the light is controlled by cutting the ending or tail of the AC voltage waveform. These dimmers allow the current to flow at the beginning of the AC cycle and cut it off at the end of each cycle. This way, it maintains a smooth dimming. In contrast to the TRIACs used in leading-edge dimmers, trailing-edge dimmers use transistors (like MOSFETs or IGBTs). This offers a more advanced approach to dimming and a noiseless dimming operation.

Compared to leading age dimmers, trailing edge ones are more versatile. They are mostly compatible with energy-efficient lighting like LEDs and CFLs. Moreover, they also work with traditional bulbs like incandescent and halogen. Trailing edge dimmers integrate with smart lighting systems, too. 

Pros & Cons Of Trailing Edge Dimmer

Difference Between Leading and Trailing Edge Dimmer

Differences In Working Mechanism 

A leading edge dimmer works by blocking the current flow at the beginning of the AC current flow and allows the current to pass after a delay. To do this, it uses a TRIAC, which is the beginning of cuts of the sin wave. This way, less power is delivered to the light, which dims it. 

In contrast, the trailing edge dimmer allows current flow at the beginning of the AC cycle and blocks the current at the end of each cycle. As a result, the lights dim smoothly. To conduct this, trailing edge dimmers use transistors instead of TRIAC. 

Load Capacity 

The dimmers come with a load capacity called operational range. The total wattage of the lighting must be within this range for proper operation. For instance, a 0-400W dimmer can run 10 bulbs of 40W (10 x 40W = 400W) or 8 bulbs of 50W (8 x 50W = 400W). That means the total should be within 400W. 

As the leading edge is designed for traditional bulbs, they can take on more load than trailing edge dimmers. These dimmers can handle 300W to 1000W or more. However, leading-edge dimmers such as LEDs or CFLs are not suitable for low-power loads. You will face buzzing noise issues when using lights below the minimum load of the leading edge dimmer, which is  20W-40W. 

On the other hand, trailing edge dimmers have a minimum load capacity of 5W-10W. So, traditional lighting with high wattage is not suitable for using a trailing edge dimmer. Instead, they are designed for low-power lights like LEDs and CFLs. 

Note: A dimmer load capacity will not be the same for incandescent/halogen bulbs (0W-400W) and LEDs, like 10W-100W. For example, if you use LEDs on the dimmer designed for halogen lights, the maximum load you can put is 100W, not 400W. 

Compatibility

Leading-edge dimmers are compatible with traditional lights with high loads, such as incandescent and halogen bulbs. If you use them for low-power lights like LEDs, it will show a buzzing noise. To eradicate this, an LED driver compatible with leading-edge dimmers is required.

Cost 

Leading-edge dimmers are cheap and easily available. It uses old technology and has a simple configuration, which contributes to its low cost. So, leading-edge dimmers are the most popular choice for incandescent bulbs. You can use them for applications that require bulk dimmers, such as commercial applications. This will reduce your cost. 

In contrast, trailing edge dimmers use advanced technology and are expensive. And cheap. So, if you have a low budget, its pricing can be concerning. However, the high initial cost is worth investing in as they are energy-efficient and a cost-effective solution in the long run. 

Dimmability

Incandescent and halogen bulbs offer a wide range of dimming (0% to 100%) for both leading and trailing edge dimmers. However, when it comes to LEDs, the dimming range for leading-edge dimmers shows limitations. It dims LEDs partially, 10%-100%. In contrast, trailing edge dimmers provide better dimming flexibility ranging from 1%-100%. 

Energy Efficiency

As leading-edge dimmers are designed for traditional bulbs that consume more energy, these dimmers are usually energy inefficient. Even when these lights are dimmed, their energy consumption does not decrease proportionally. Now, you may question what if we use LEDs with leading edge dimmers. Actually, these dimmers are designed for high-wattage bulbs, whereas LEDs are low-wattage. So, even if you use energy-efficient bulbs with leading-edge dimmers, it becomes challenging to control efficiency. 

On the contrary, trailing edge dimmers are highly energy efficient. Unlike leading-edge dimmers, they don’t generate heat or waste energy. So, if energy efficiency is your priority, pair up LED lighting with trailing edge dimmers. 

Noise and Electromagnetic Interference (EMI)

Leading edge dimmers use TRIAC, which suddenly cuts off the starting of the AC waveform. This makes the filaments or components of the bulb make a buzzing noise. Such noise becomes more prominent when leading dimmers are used with low-power lights like LEDs paired with incompatible dimmers. Moreover, the sudden fluctuation of electrical current produces high-frequency signals. As a result, other electrical devices, like radios, Wi-Fi routers, TVs, etc., face interference and signal issues. 

On the other hand, trailing edge dimmers use transistors that cut out the AC waves smoothie from the end. As a result, no buzzing noise is produced. This is further less likely to interfere with electronic devices.

Application 

Leading edge dimmers are widely used in residential and decorative lightings such as chandeliers and floor lamps. Again, in spaces where high-wattage bulbs are used, leading-edge dimmers are a compatible match, for instance, in retail stores. Besides, it is also budget-friendly and used in large-scale applications.

In contrast, trailing edge dimmers are mostly used with modern lighting like LEDs. These are suitable for low-load applications. Besides, you should choose trailing edge dimmers in a smart lighting solution. 

Quick Differentiating Chart: Leading VS Trailing Edge Dimmer 

Which Is Best For LEDs: Leading VS Trailing Edge Dimmer?

Trailing edge dimmers are designed especially for LEDs and other low-power operating fixtures like CFLs. These dimmers have a lower load capacity range compared to leading-edge dimmers, which is ideal for LEDs. 

Besides, the dimming of the trailing edge is smoother than the leading edge. They further cause no buzzing or noise issues and are highly energy efficient. All these factors make trailing edge dimmers best for LEDs.