When my sister and I were little kids, we enjoyed turning the lights on and off repeatedly (to simulate lightning storms or some such thing.) We were told by our parents not to do that, because it wasted a lot of electricity.
Would turning lights on and off, over and over again, really waste more electricity than just keeping the lights on the whole time?
IANAE, but I wouldn’t think you’d use extra electricity. Maybe wear out the bulb (or switch) faster. More likely they just found it annoying.
I think CFLs require a surge of electricity to turn on. Incandescent, not so much.
Actually, it is “sort-of” true for incandescent lights.
They pull an enormous amount of current when initially turned on - something like 10x their rated current. However, this turn-on spike is very short, on the order of a few hundredths of a second, so it really doesn’t amount to much waste, unless you are doing it over and over again for hours…
But - because of the huge in-rush current, most incandescent lamps will fail during turn-on, and doing this (rapidly turning them on and off) will definitely shorten their life.
Short answer: Not much extra electricity, but it will cause you to go through light bulbs faster.
Conversely, bulbs will last a lot longer if you limit the inrush. I have expensive remote controllable (Insteon) dimmers, but you can get electronic dimmers like Levitons toggletouch for a lot cheaper. They have soft start, where they fade a bulb on over 3 seconds instead of blasting it with electricity. (Toggeltouch are fixed at 3 seconds, but Intsteon you can adjust the rate from 0 seconds to 9 minutes).
Maybe if you have gets this would take away the temptation to flash lights on and off an annoy adults…
Turning lights on and off is what dimmer switches do. The bulb is powered on later (and shorter) to dim lights - consume less power. You werw only duplicating (at a slow rate) what dimmer switches also do.
A dimmed incandescent bulb operates less efficiently - wastes power. It may consume less power. But creates even less light. Creates less light and created more heat from each watt.
I am under the impression that turning CFL bulbs on for short periods of time is actually bad for them–that a CFL in a closet that gets turned on and off several times a day will have a much shorter lifespan than a bulb that is turned on and off just a few times per day.
I have no idea how that idea got into my head and have no idea whether it has a shred of credibility. Can anyone chime in and set me straight?
it true.
To elaborate, it isn’t so much the inrush surge (which is different than an incandescent and is due to a capacitor filtering the rectified AC voltage; incidentally, the rectifier can be seen as a switch being rapidly turned on and off 100/120 times a second (full-wave), so this isn’t any different from normal operation) but the stress on the fluorescent lamp itself, especially when it is turned on when cold since the cathodes get damaged a bit when current flows while they are still cold; failure results when the electron-emitting material gets completely stripped away (normal operation also slowly depletes the material, the same failure mode as in vacuum tubes). This could be largely avoided if the cathodes were allowed to pre-heat before current passes through the bulb but the demand for “instant-on” CFLs overrides this (done by applying a high voltage to the lamp so it conducts, if inefficiently, thus the dimmer light when first turned on, until the cathodes warm up).
How about LED’s? Do those bulbs care?
Not nearly as much.
If they have well-designed driver circuitry, turning them on and off many times shouldn’t be a problem. Still, electronic devices “like” to be either on or off. An on-off transition is always more stress.
Mythbusters tested this. The worst startup performance was old fashioned flourescents, where the startup load is 23 seconds worth of normal running power, so that might be the only case where rapid on/off cycling would waste an appreciable amount of electricity over just leaving the lights on.