Switch off or leave on?

travelgran

We have a number of fluorescent lights in the house and were once told that switching them on and off used more electricity than leaving them on all day because of the energy used to power up the tubes initially.
Can anyone tell me if this is true or is it an urban myth?
Thanks

Pincher

True & False.

Start up current IS higher, but it's like starting your car.
You wouldn't run the engine all day.

Robisere

Hello
Taken from WIKI:
"Starting

The mercury atoms in the fluorescent tube must be ionized before the arc can "strike" within the tube. For small lamps, it does not take much voltage to strike the arc and starting the lamp presents no problem, but larger tubes require a substantial voltage (in the range of a thousand volts).
Electronic starters use a more complex method to preheat the cathodes of a fluorescent lamp. Electronic starters are made in the same physical case as glow starters for direct replacement. They commonly use a specially designed semiconductor switch. They are programmed with a predefined preheat time to ensure that the cathodes are fully heated and reduce the amount of sputtered emission mix to prolong the life of the lamp; typically it is claimed that the life of a lamp frequently switched on, as in domestic use, is prolonged by a factor of 3 to 4 times. Start time is typically 1 to 4 seconds. Electronic starters contain a series of capacitors that are capable of producing a high voltage pulse of electricity across the lamp to ensure that it strikes correctly. Electronic starters only attempt to start a lamp for a short time when power is initially applied and will not repeatedly attempt to restrike a lamp that is dead and cannot sustain an arc; some will automatically shut down a failed lamp. This eliminates the re-striking of a lamp and the continuous flickering on and off of a failing lamp with a glow starter. Some fast-start electronic starters can strike the fluorescent tube within 0.3 seconds."

I think that you have to know which size and type of lamp, together with the type of starter mechanism, you possess, but basically if you are only leaving the lighted room for a short time (say, up to 30 mins.) I would leave it on. Switch off, if you are leaving for longer. Larger, and/or commercial lamps are a different story. As to all day, in a normal domestic environment, definitely switch off. Hope that helps.

travelgran

Thanks for that!

HappyMJ

travelgran wrote: »

Thanks for that!

The only CFL that seems to fail on me regularly is the one in the bathroom. It gets turned on and off many times per day. It so far has never lasted for anywhere near the rated number of hours before failing.