The $60 Lightbulb

By: Gary Foreman

Hi Gary,

Should we turn off the compact fluorescent bulbs each time we leave the room at least 15 minutes? Do these bulbs use a lot of electricity when turned on and off? Thank you for your advice.


Mai asks a very good question. And, as more people shift to compact fluorescent (CF) bulbs, others will be interested in the answer as well.

The reason that people are gradually beginning to use CF bulbs is simple. In many applications they can save money because they use less electricity. Generally a compact fluorescent will only consume one third as much juice as a regular bulb.

The CF will cost more to buy. But, the bulb will last up to ten times as long as a regular bulb. So any cost comparison needs to include the cost of many regular bulbs.

According to the U.S. Department of Energy, a 100 watt incandescent bulb can be replaced by a 27 watt compact fluorescent. After four and one half years the CF will have saved $62.95 compared to the incandescent including the cost of the bulbs used.

Compact fluorescents also operate at a cooler temperature. Less than 100 degree F. in most applications. So the bulb doesn't create heat that needs to be removed by an air conditioner.

Not surprisingly, CF's are good for the environment. According to the Energy Star program if everyone is the U.S. joined her and just replaced one regular light bulb with a compact fluorescent it would have the same effect as taking one million cars off the road.

Now that we know why people are shifting to compact fluorescents, let's try to answer Mai's question about whether to turn it off when you leave the room for a few minutes.

Fluorescent lights work a little different than the incandescent bulb that Thomas Edison invented. Tom's bulb glowed because electricity heated up a filament. Once heated the filament glowed and produced light.

A fluorescent light consists of a ballast and a gas filled tube. The glass tube is also coated with phosphor. The ballast sends electricity through the tube. When the gas in the tube is 'excited' it causes the phosphor coating to emit light.

All fluorescent lights take about a half a second to start and up to two minutes to reach their full brightness. It is commonly believed that they use more electricity in 'starting up' than they do while the lamp is burning. That is not true.

Energy Smart, a Western Australian government initiative, says that you should turn off a fluorescent anytime that you'll be out of the room for ten minutes or more.

Turning a CF on and off frequently will reduce it's energy effectiveness. But, even if you do cycle it often, it will still be more energy efficient than a regular incandescent bulb.

Mai will also reduce the lifespan of her CF if she turns it on and off frequently. The Energy Star website recommends that you use CF bulbs in places where they can operate for several hours at a time. For instance, Mai wouldn't want to use a CF in places where lights are on for a short periods like a closet or bathroom. A family room is often ideal for CF usage. And Mai can even buy 3-way CF's and ones that are specifically made for use with a dimmer.

Congratulations to Mai. Not only is she saving money and the environment, she's also learning how to get the most out of a new technology.

Gary Foreman is a former purchasing manager who currently edits The Dollar Stretcher website and ezine

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