Which uses more electricity?

choccyface2006

Turning a switch off and on several times in say an hour or just leaving it on?

For example, my daughters often leave the television on when the have left the room and it really annoys me so I turn it off. 10 minutes later they might come back in and turn it on again and the process might get repeated again and again.

When I was little my dad used to say that it cost more money to turn it on and off and on and off because it used quite a bit of power during the turning on period therefore it was better to leave it on. The same would go for most things like lights.

Does anyone know if this is true?

Thank you!

Sarah x

thescouselander

It will actually use less electricity to switch off the TV when not in use (even for only 10 minutes) however, you might find that this repeated switching on and of shortens the life of the TV.

Cardew

choccyface2006 wrote: »

Turning a switch off and on several times in say an hour or just leaving it on?

For example, my daughters often leave the television on when the have left the room and it really annoys me so I turn it off. 10 minutes later they might come back in and turn it on again and the process might get repeated again and again.

When I was little my dad used to say that it cost more money to turn it on and off and on and off because it used quite a bit of power during the turning on period therefore it was better to leave it on. The same would go for most things like lights.

Does anyone know if this is true?

Thank you!

Sarah x

It is not true!

With some lights they use more pwer for a second or 2 - but it saves money to switch off power to all devices even for a short time.

choccyface2006

Thanks to both of you! I will stick to turing them off them, maybe be careful with the tv though!

moonrakerz

choccyface2006 wrote: »

Thanks to both of you! I will stick to turing them off them, maybe be careful with the tv though!

Surprisingly, that is why TVs have a "standby" mode.

Need_More_Money_2

There did used to be the same argument for leaving computers switched on. The on/off switch, being mechanical, was more likely to break if repeatedly used. There may also be issues related to repeated heating and cooling of the components if switched on and off. So it's not about using less electricity, it's about whether it ends up costing more to replace the equipment than you save in electricity. I'm not sure if the same applies to light bulbs

rygon

Switches are made to be turned on and off...thats there design so i doubt that normal usage (on and off 10times a day or so) is going to make any difference to its life. With things getting powered on and off (like bulbs) its down to thermal stress...If glass is heated to quickly or cooled down too quickly then its going to put a lot of stress into the material ..if this happens then the glass shatters (with air around it to take the heat away thermal stress is going to be low) The only part which will matter is the joint from the metal to the glass (as they will expand/contract at different rates) but for the price of electricity compared to price of bulbs, turning them off will save money.

Searcher

It really depends on what is being turned on and off and how long you're going to leave it on for.
It used to be the case that a flourescent lamp would use something like 8 times the watts when starting as it would when it was running so there was a valid argument for leaving it switched on rather than turning it on 7 or 8 times an hour. With technology advancements though I'm not sure if this is the case any more.

In the case of a normal light bulb though it makes no difference if you turn it on once or a 1000 times.

Tv's and the like use something like 33% of the power on standby as it does when it's switched on so if you're not using it turn it off lol

Cardew

Searcher wrote: »

Tv's and the like use something like 33% of the power on standby as it does when it's switched on so if you're not using it turn it off lol

I am sorry but that is totally wrong. It is more like 1% and costs can be measured in pence per year.
Most modern TVs(last 10 years or so) have extremely low Standby consumption.

My 3 TV's( 2 x 6+ years old CRTs and a modern LCD) all have a standby consumption of under 1 Watt and I have never heard of a standby wattage greater than 3 watts.

Look at the manufacturer's data available on-line.

Can you give any examples of fully on/standby wattages that support your statement?

tr3mor

Searcher wrote: »

In the case of a normal light bulb though it makes no difference if you turn it on once or a 1000 times.

In the case of incandescent light bulbs switching them on and off affects their life. When switched on, a small surge of current will pass through the cold filament, since it has less resistance.

This shouldn't contribute to any electrical costs, but will shorten the life of the bulb, so you shouldn't really be flicking them on and off all the time.

And as Cardew says, you'll be struggling to find a TV for sale that uses more than 1W in standby, let alone a third of the power of it in full use.

Care to contribute anything based on facts?

Jonesya

tr3mor wrote: »

In the case of incandescent light bulbs switching them on and off affects their life. When switched on, a small surge of current will pass through the cold filament, since it has less resistance.

This shouldn't contribute to any electrical costs, but will shorten the life of the bulb, so you shouldn't really be flicking them on and off all the time.

As I understand it the main cause of failure of bulbs is due to loss of metal from the filament caused by evaporation during use - the current surge at switch on may precipitate the failure but the cause was the deterioration of the filament.

If you were building a flashing sign then you might worry about the impact on bulb life but for a typical domestic situation it wouldn't be an issue would it?