how to dim led lights

It’s a widely held belief that if you switch out your incandescent bulbs for LED bulbs, you’ll be sacrificing appealing mood and ambiance for big energy and money savings. One reason for this misconception is that LED bulbs aren’t typically dimmable using the existing dimming wall fixturethat works for incandescent bulbs. 

Why? Well, traditional dimmers for incandescent lights work by cutting down the amount of voltage that reaches the filament. In LED lights, all of the extra circuitry gets in the way and does not allow the dimmer to have a direct effect on the amount of light emitted from the LED bulb.

However, there are other ways to dim LED lights, one of them being pulse width modulation (PWM). PWM causes the LED to flicker on and off at a rate undetectable to the human eye; the flickers are then staggered depending on the desired amount of light. 

PWM is difficult to achieve and requires special circuitry including microprocessors and oscillators. In addition, voltage reduction can also dim LEDs, but the dimming effect is not linear, meaning the illumination will abruptly shut off once the voltage drops below what is needed to power the light to begin with.

Neither of these dimming techniques is particularly desirable, and can be tricky to install. Luckily, Elemental LED has found a better way to set the mood, using our dimmable power supply, which is a multiple voltage transformer that can be used in all install situations. Using this product, you can install any low voltage LED product to work with your already existing dimmer. No rewiring will be necessary, you can simply tap into the power supply adjacent to your new LED product, and—voila!—you have dimmable LED lights!

Low Voltage Dimming

Low voltage dimming is a possibility when using external drivers.

Not all external drivers will be compatible with low voltage dimming methods. However, if you opt for LED controlled by an external driver, the option of choosing a low-voltage dimmable driver is open to you.

The type of low voltage dimming available depends on the type of driver being used. Both constant current drivers and constant voltage drivers can use a method called pulse width modulation.

Only constant current drivers are compatible with constant current reduction (CCR). For more on the difference between types of drivers see our LEDs and Drivers Guide.

Unlike mains dimming, both of these methods send an electronic message to the driver, and it is the driver which then dims the lamp using its electronic components.

In low-voltage dimming, all the dimmer is doing is telling the drivers what to do. This is different to mains dimming because with mains dimming the dimmer itself reduces the power and sends it through the driver.

As the dimmers in low-voltage dimming do not do the work, but instead tell the drivers what to do, they use protocols, which is just an agreed way of transmitting information.

A low-voltage dimmer passes on information and commands with electrical signals. We will briefly outline some common protocols at the end of this article.

Pulse width modulation (PWM)

Pulse width modulation works on the same principle as mains dimming. It switches the lamp on and off several times a second to reduce the total amount of light produced.

As low-voltage dimming has the driver do the work, pulse width modulation does not have to chop-up a mains signal. The driver can switch the direct current it produces on and off to dim.

A great advantage of PWM is that colour rendering is the same at all light levels from dimmest to full brightness.

Drawbacks can include strobing. Although the rapid on/off switching is too fast for us to consciously notice, some people report problems such as headaches when exposed to this type of lighting. In laboratory conditions, the pulsing can cause damaging electro-magnetic damage to very sensitive devices

Neither of these drawbacks are of concern to most users. In general, those who opt to use PWM over CCR do so because they are using constant voltage drivers which are not compatible with CCR. Otherwise, they are just looking to avoid a drawback with CCR.

Constant current reduction

Unlike mains dimming or PWM, CCR does not turn the power off and on. Instead, constant current dimming steadily reduces the current delivered to the light, which then dims as the current is reduced. That means instead of a wave, you have a steady supply of power.

This resolves any potential strobing and electromagnetic issues but colour rendering can vary when the lamp is dimmed.

PWM and CCR are both well-established systems. Unless people have a particular drawback they are trying to avoid there is not much to choose between them.

Protocols

Protocols are what the dimmer in low-voltage dimming (both PWM and CCR) uses to ‘speak’ to the drivers: that is, to tell them how much to dim.

There are several different types of protocol but the most common are 0-10V and DALI. These work in different ways but they are simply the language used by a dimmer to tell drivers what to do. It is therefore essential you get a DALI compatible driver if you want to use a DALI dimmer and so on for the other systems.

LED is the most efficient type of light bulb on the market. A 6 watt LED is now similar to a 60 watt incandescent with 13 times the life, but without the heat output of the incandescent.

That’s actually a small problem. Older dimmers “read” wattage rather than lumen output. As such, most dimmers cannot dim a low wattage bulb.

LED is the most efficient type of light bulb on the market. A 6 watt LED is now similar to a 60 watt incandescent with 13 times the life, but without the heat output of the incandescent.

That’s actually a small problem. Older dimmers “read” wattage rather than lumen output. As such, most dimmers cannot dim a low wattage bulb.

Traditional Kitchen by Tempe Lighting Inspired LED

LED’s contain electronic components that regulate voltage and output so that the LEDS illuminate correctly. Sometimes these components do not “communicate” well with the electronic components in the dimmers.

Confused? Don’t be. We will show you a few LED compatible dimmers.

Electronic vs. Magnetic Dimmers

The ability to dim an LED is easy as long as you have the correct components. Many of the LED fixtures​ require an “electronic low voltage dimmer”. This is because the electronic devices used in the LED’s will not work correctly if you use a “regular” incandescent dimmer. Several manufactures offer specially designed electronic dimmers. Luton, Leviton and Legrand all offer dimmers that will do this. These dimmers do cost a bit more than conventional dimmers, usually between $70 to $200.

Electronic Dimmers

The Lutron Diva Series DVELV300P below is a style of dimmer that has been around for a while and works nicely with existing decora style dimmers and switches. Also is shown a Leviton VIzia Dimmer, $204.

Magnetic Dimmers

Some also use “Magnetic” low voltage dimmers. Magnetic dimmers are usually found in recessed and LED tape (see diagrams below for images). The prices are usually a bit less than the electronic counterparts but unfortunately they are not interchangeable.

Universal Dimmers

Legrand offers the best solution. They have a true Universal dimmer, which can dim both. This eliminates any guesswork. This is useful when you want all of your devices to match around the house and have a multitude of lighting types. Razorlux offers several of their series of dimmers with this ability.


Leave a Reply