Dimmer vs savings

Not in the grand scheme of things. You might save two bucks in a year. Or there might not even be any savings at all if you frequently operate the lights at >75% brightness, due to the dimmer's inefficiencies.

depends on where you set it -- and on what basis you calculate the savings (e.g. if the alternative is smaller bulbs, then probably not)

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Well the lamps use less power when dimmed, they're less efficient too, but if you need full brightness sometimes and not others then yes a dimmer will give you some savings, but convenience is the main reason for installing one.

A dimmer will not save very much in power consumption. When the lamp is dimmed, it is less efficient. Its heater resistance will go down a little, thus it will not draw much less current in relation to the loss of light output.

What you should really be going for, is to use a smaller wattage bulb, or get rid of the dimmer and use a compact fluorescent lamp. These lamps are about 85% efficient, and will consume much less power. It is not recommended to use a dimmer on a compact fluorescent lamp, unless it is a model that is designed to do so. If you try it on a dimmer and it is not rated, there is a chance that both the dimmer and the lamp will be damaged.

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"taxpayer"  wrote in message 
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Hi Brains, a question is there any saving on energy by using a dimmer ?
Thankx

Light goes down with ~ 4th power of current and temperature so at 50% light you still consume 70-85 % of full power + dimmer power. Dimming ordinary lightbulbs is a very inefficient way to save power. (Sometimes it may look great!! -)-)-) )

The biggest savings might be prolonging the light bulb life, if you always dial up the light so that you have eliminated the cold filament inrush current that occurs when you have the light on a regular switch.

H. R.(Bob) Hofmann

Please let's ont start a thread on this - again... :)

The slow inrush has only a very small effect on lamp life.

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That and incandescent lamps cost virtually nothing, you can get four for a buck, though I don't use them for much of anything anymore.

Same here -- that's probably why they're so cheap.

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Thanks guys

Yep:

Cost of 100 W incandescent lamp: $0.25.

Cost of electricity to run 100 W incandescent lamp over its life (750 hours): $7.50 or more.

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Does that also apply to LV halogen lighting? I have a few halogen fittings in my home, and the bulbs definitely last a lot longer in the one I have with an 'electronic' transformer which ramps the bulbs up rather than switching on instantaneously. I fact I don't recall changing a bulb in it in the three or so years it's been up. OTOH the iron transformer instant-on ones pop bulbs every few months, though that could be down to a less stable transformer output.

I'm wondering if the slow-on is a way of protecting the SMPS from being blown if a bulb blows, IOW it ramps the output up and checks for overcurrent before applying full voltage, rather than being a bulb-saving feature?

Dave

To some extent is should apply. Even with the halogen cycle, there will still be portions of the filament that get narrower, and these dissipate a higher proportion of the power. Eventually, they being the weak link, will fail.

Might be but that sounds like a lot more intelligence than I'd expect of a power supply!

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I have used the dimmer type fluorescent lamps. Very nice. Too bad they don't have more on the market, as such, they are expensive. Payed about $20 for one at The Home Depot, then I could not find them there. It also was a very nice color. I use vertually all fluorescent lamps when I can. Leave one on outside all day long. The 5 pack for $10 at The Home Depot lamps are very nice. I had installed halogen recessed kitchen lamps in previous home. They were too bright for normal viewing, so a dimmer was mandatory, and they do save money and heat. Now the thing I want to know, is how the two fluorescent lamps differ in circuitry, and how that can cost $18.

greg

I guess what you meant was 15 percent efficient at producing useful light. This is still 3 times the efficiency of a typical incandescent lamp.

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A lot of it is construction quality, but dimming ballasts have special considerations. They have to provide active cathode heat which is inversely proportional to arc current otherwise the cathodes will sputter badly as the lamp is dimmed. This is even more tricky to do well when you can't have a separate dimmer circuit independent of power supplied to the lamp.

Market share is another factor, there simply isn't as much market for dimmable CFLs, hence the higher price.