Dimming flourescents

Without seeing your lights, and using mine for examples, they are typically undimmible. Only special flourescents are dimmible. Also, real warning, I believe dimming undimmible lights is a fire hazard. So, read the instructions, and use the product safely.

hth,

tom @

I always thought that fluorescent bulbs were gas and required a minimum voltage to conduct. How do they dim a fluorescent bulb? Thanks.

It takes a little more engineering but it's quite possible to "dim" a fluorescent lamp.

I don't know how "they" really do it, but a way to "dim" would be just to replace a 40 watt ballast with a 20 watt ballast. The bulb would still "see" the voltage needed to start but would only get HALF the current.

Likewise, it's possible to over drive a fluorescent lamp. Just replace a

Dimming ballasts vary the current through the tube; the voltage is substantially constant. Dimming ballasts keep the filaments at the end of the tubes at full voltage while the arc current is lowered. One of the problems with a non-dimming ballast is the filament voltage is 'dimmed' also.

Bud--

Ken wrote:

Ah, I did not think of limiting the current! Don't these lamps flicker if they reduce the current? Or do they simply dim?

In many cases, it is done by rapidly chopping the current. Actually, triac phase control dimmers can be used (and used to be), but it's a bit more complicated than dimming a filament lamp.

They will flicker because when the current drops below a certain level, there's not enough electron/ion bombardment to keep the filaments hot enough to conduct into the gas fill by thermionic emission. By separately heating the filaments, this problem is resolved. Actually, running at reduced tube current without separately heating the filaments, even before it's low enough to cause flicker, will wear out the electron emitting coating on the filaments much faster than running at the correct power rating, contrary to what one might imagine.

Certain compact fluorescent bulbs with included ballasts are dimmable since they use a ballasts that responds to triac dimming. They don't dim as well or as fully as an incandescent lamp.

Full range dimming ballasts are avaialble for standard linear fluorescent tubes. You just replace the fixture ballast with the dimming ballast and get good dimming to around 10% in some models.

Yours,

Doug Goncz Replikon Research Falls Church, VA 22044-0394

Re: Dimming flourescents Group: alt.engineering.electrical Date: Thu, Mar 31, 2005, 12:40am (EST-3) From: snipped-for-privacy@aol.com Certain compact fluorescent bulbs with included ballasts are dimmable since they use a ballasts that responds to triac dimming. They don't dim as well or as fully as an incandescent lamp. Full range dimming ballasts are avaialble for standard linear fluorescent tubes. You just replace the fixture ballast with the dimming ballast and get good dimming to around 10% in some models. Yours, Doug Goncz Replikon Research Falls Church, VA 22044-0394

----------------------------------------- I've never wiredup a fluor/. lamp to a dimmable ballast (yet) but last i studied they required a 3 conductor circuit.the ones i got made me remove the occ/ sensor switch, it flickered viciously on & off went full on then wouldn't shut off to a constant flutter. Roy Q.T. Bx,Ny,USA 14055