I know it is recommended that incandescent lights be turned off whenever they are not needed. But what about fluorescent lights?
The light produced by fluorescent lamps involves a process that relies upon a small quantity of metal being sputtered away from components at the end of the tube or bulb called electrodes. This produces a gas discharge inside the lamp that results in light as particles of electric energy (electrons) strike a phosphor coating on the inside surface. Although this process is ongoing while the lamp is burning, it is most severe during start-up. While fluorescents typically have a significantly longer service life than incandescents, regularly cycling the lamps on and off more often than once every ten minutes will affect the service life of the electrodes, increasing the potential cost and aggravation of having to frequently replace the lamps. So if you'll be away more than ten minutes, it may make sense to turn the lights off; but leave them on if you'll be back in less than a couple of minutes.
By the way, a belief exists that fluorescent lamps consume an enormous amount of energy when starting up. Not true!
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