Re: LED lamps on dimmer circuits

John Gilmer wrote:
> I tried to post before but my news server seems to have screw up.
>
> Anyway, I finally am seeing some LED 120 volt lamps (at Wally World.)
>
> They come with the warming to not use them on dimmer circuit but the best
> application for now in our place is on an X-10 controlled light fixture.   I
> haven't tried dimming but with one "normal" lamp and one LED lamp on the
> circuit is seems to work OK.
>
> SO:   what's the problem with dimmers and LED lamps?   What's the potential
> for harm if you try to dim it?
>
> Since I have your attention, what about CFLs?    What potentially could "go
> wrong" if you "dim" a CFL bulb?
>
> EMWTK
>
>
> ** Posted from http://www.teranews.com **

I haven't seen these line-voltage lamps (but I am going to visit Wally
World just to do so), but here is a guess at why they say not use a
dimmer: they incorporate a transformer.

Anything that has a transformer (or ballast) in it, including
fluorescent lights, will run hot, and may even catch fire on a dimmer.

This is because a transformer is designed to run on a fairly clean fixed
frequency. Some of the pricier fixtures will allow either 50Hz or 60Hz,
but they cannot deal with harmonics. Dimmers, because they work by
abruptly starting the current part-way through each half-cycle, generate
a large amount of harmonic energy.

Incandescent lights have no problem with this, and it makes the dimmer
cheaper, but it will overheat anything with a transformer or ballast.

Anthony Straight
http://tonyelectric.com

** Posted from http://www.teranews.com **
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