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"Leaving fluorescent lights on saves energy"

You may have heard people say: “It’s best to leave fluorescent lights on: it’s cheaper than switching them on and off”. How do you respond to this?

People who promote this are probably well meaning but wrong. Usually they say it takes a lot of energy to start up a fluorescent and secondly, say that switching on/off lights reduces the lamp life and there is the expense of replacing the lamp.

The energy consumed to start a typical lamp is the equivalent of 2 seconds running time, so it is wrong to say it takes a lot of power to start them. It is true there is a current surge but this takes place in less than one-eighth of a second and because it happens so quickly it takes very little energy.

It is true that switching on/off fluorescents reduces lamp life but lamps are designed to be switched on/off up to seven times a day without any effect on their life. How many times a day do your colleagues switch on/off to save energy? Probably not enough times to reduce the lamp life.

A short energy mythbuster film is available on YouTube.

  • Lamps are designed to be switched on/off up to seven times a day
  • The advice on fluorescents is simple: Switch off and save energy.