| Are your LEDs really Dimmable?
Most existing dimmers were designed for filament lamps, which absorb much more electrical power than an LED lamp. A 5-watt LED, claimed "dimmable" by its manufacturer, connected to one of these traditional dimmers may flicker, fade, buzz, or suddenly switch off. It will suffer a dramatic reduction in lifetime. The behavior of an LED lamp on a dimmer designed for a filament lamp is completely unpredictable: You may try out a lamp at home, where it dims perfectly, and then discover that your neighbor can't dim the same lamp. Why? You were lucky enough to choose the right dimmer.
While there are many dimmable LED lamps on the market, some customers are becoming dissatisfied with their performance and lifetime. The fact is that there are plenty of dimmers suitable for filament lamps, but they are not compatible with the internal control gear of an LED lamp. Although some dimmers might function properly, manufacturers never specify which dimmer is compatible with their product.
What Will Work?
It is the internal control gear (the integrated driver in the LED lamp) which determines the dimmer's effectiveness. In both cases the internal circuit of the lamp works in high-frequency (typically in the range 30-40kHz) and the external dimmer should be able to change this internal operating frequency in order to change its lumen output. Traditional dimmers do not do this because they operate on 50/60Hz main voltage (100V to 270V). Electronic dimmers like TRIAC (Triode for Alternating Current) and IGBT (Insulated Gate Bipolar Transistor) work in high frequency, but they cause problems for LED lamps because they are designed for higher workloads or for external converters (such as independent electronic transformers or ballasts).
Other "dimmers" like the endowed DALI (Digital Addressable Lighting Interface) system for low voltage signal (1-10Vcc) are designed only for dedicated external control gears which cannot be integrated inside an LED lamp. A solution with the DALI system (1-10Vcc signal) can be applied to LED lamps working at 12V, but it needs a DALI compatible driver plus a dedicated DALI control unit.
However, the DALI system is very expensive and recommended only if you have to generate "scenes of light" with many sources and modalities of light such as high end theaters, churches, galleries, or showrooms.
The End Result
Even the lamps that seem to dim without incident are not going to last anywhere near as long as advertised. How long will they last? It is possible that in its current form, the life of an LED driver can be reduced to as little as one-tenth of its expected lifetime.
Most lamp companies are already aware of this situation. High Power LEDs are supposed to last 50,000 hours; nevertheless, most reputable manufacturers will only claim 30-35,000 hours, based on the lifetime of the driver. Therefore, the race is on to develop an internal gear that works with all standard dimmers without compromising the bulb's expected longevity. | 
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