Why Dimming Bulbs Don’t Always Dim to Zero Percent|
Article - January 26, 2016 By LarsonElectronics.com
Why Dimming Bulbs Don’t Always Dim to Zero Percent
Dimming is a functionality that is highly valued by individuals who are interested in custom lighting systems. Setting up smooth dimming features can be a daunting task, because there are several factors to take into consideration. Fixture-to-dimmer compatibility, electrical configurations and personal dimming preferences are just some issues that individuals must conquer when installing light dimmers.
With focus on personal dimming preferences, some people want to be able to dim their bulbs down to zero percent. But this feature isn’t always available, leaving some people scratching their heads.
Most bulbs don’t have a problem with dimming down to 60 or 40 percent. Issues start to surface when dimming down to single digit levels and ultimately zero percent. Incandescent and halogen bulbs can easily dim down smoothly to one percent with minimal effort and no noticeable flickering or buzzing. On the other hand, dimmable LEDs are prone to displaying inconsistencies in output when dimming at extremely low levels- usually 10 percent or lower. Dimming lights is a complicated process, because it requires the ballast or driver (depending on the type of fixture) to control the amperage and the voltage in a precise manner.
Most standard dimmers are designed to handle high electric loads that are commonly associated with traditional luminaries. Because of this, some dimmers have a difficult time “reading” or picking up low electrical loads, such as loads from an energy efficient LED bulb. When attempting to dim down to zero percent, the bulb may drop out or turn off, as it hits the lower range of the available settings. This happens because the setting of the dimming switch’s lowest voltage is lower, compared to the bulb’s voltage requirements during operation. As a result, dimming is limited to a minimal setting (for example, 15 percent); and attempting to dim down to a value lower than that setting would cause the light to turn off prematurely.
Failing to meet a dimmer’s minimum load may result in the following:
• Reduced dimming capabilities (range)
• Glowing (also known as ghosting)
• Inconsistent dimming features
Adhering to a dimmer’s minimum load is crucial to preventing drop outs at low settings. If one is unable to meet to such prerequisites, using a compatible dimmer that can operate at low electrical loads is another effective solution to this issue. Alternatively, some circumvent the problem by pushing an additional electrical load to meet the requirements of the dimmer.
Dimming Factors to Consider
Choosing a working dimmer requires addressing numerous factors during the buying process. Below are some tips on purchasing lighting products that can meet one’s dimming needs:
• Dimming levels: Before heading to the store, it is important to know the amount of dimming you need for the location. For example, a commercial lobby may only need dimming down to 20 percent, while a bedroom would require dimming down to zero percent.
• Bulb preferences: Not all lighting technologies handle dimming functions the same way. Furthermore, some dimmers only work with traditional luminaries and do not perform consistently (or lack compatibility) when paired with newer bulbs, like LEDs. Individuals should carefully note that all incandescent and halogen bulbs support dimming, but not all LEDs are dimmable.
• Check the load: Overloading or underloading a dimmer almost always leads to inconsistent performance and shortened lifespans. Be sure to check the suggested load requirements of the dimmer.
• Dimming technologies/methods: There are several dimming options available in the market today (forward phase control, trailing edge, DC dimming and etc.). Each type has its own set of advantages and limitations. In most cases, addressing the factors above will lead you to a specific type of dimming method that can handle your preferences
Most of the information you need, while purchasing the correct bulb and dimmer, can be found on the label of the units. Also, don’t forget to test the products inside the store before committing to the purchase.