Can a halogen light be dimmed

I have 8 under the cabinet lights in my kitchen that use 15W halogen bulbs. When they're on and your in the kitchen it's okay but I'd like to dim them after the kitchen chores are done. I was thinking of either adding a dimmer switch (yuck!) or automate them using a motion sensor that detects when there is no activity for a period of time and then dims them.

I am using homeseer.

Thanks Ray

Reply to
labbie48
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On Fri, 06 Jan 2006 13:06:34 -0500, labbie48 wrote (with possible editing):

Yes, halogen bulbs can be dimmed. However, they are usually available in several voltages. If they are 120vac, any dimmer can handle them. If they are low voltage (through a transformer) you must use an X-10 dimmer designed for inductive loads.

Several manufacturers claim that halogen bulbs must be run at full temperature periodically to lengthen their lives and remove the carbon buildup which will form if they are run at reduced voltage. I have no idea if that's true. We have a chandelier in our front hall which always runs at reduced voltage. It uses about 30 high voltage bulbs and has been running for several years now. It switches on at sunset and runs to 11 pm every day. Every now and then it is switched on by a motion detector which runs the bulbs at a higher level.

Reply to
L. M. Rappaport

Yes, it's true. I'ver used them in dimmable theatrical fixtures for years. Leaving them dimmed without periodic use at full power can shorten the life of the bulb. More importantly for theatrical use, it can also change the color temperature of the bulb.

Reply to
Robert L Bass

It's true. The darkening you see on ordinary incandescent bulbs after a while is tungsten which evaporates from the filament and deposits on the glass envelope. In a halogen bulb, the envelope is quartz and reaches an operating temperature which would soften or melt ordinary glass. At this temperature a chemical reaction takes place whereby the tungsten deposited on the quartz reacts with the halogen gas in the envelope to form a gaseous tungsten halide. When this halide diffuses over to the incandescent filament which is even hotter yet, it decomposes and redeposits tungsten on the filament, preferentially at its hottest spots. This allows the filament in a halogen bulb to be operated at a higher temperature than an ordinary bulb and thereby achieve greater efficiency without shortening its life.

Operating a halogen bulb at reduced voltage lowers the temperatures of both filament and quartz envelope and reduces (or can halt) the reactions in the tungsten-halogen cycle. The working temperature range of a halogen bulb is controlled by the particular mixture of halogens within the envelope. Dimmable halogen bulbs are designed to have a wider working temperature range, trading off against other desireable characteristics like peak efficiency.

Regards, Charles Sullivan

Reply to
Charles Sullivan

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