How much to leave kitchen light on?

melbury

This is a continual source of disagreement between myself and OH. Our kitchen is somewhat on the dingy side and so I always walk in and switch on the light, which really annoys him:D

I am sure that I read somewhere it is cheaper to switch on a fluourescent tube and then leave it on rather than switching it on and off, as most of the power used is in starting it up.

Anyone know if this is true? It is a 6 foot tube 70 watt.

Hopefully it is me that is right.

Premier_2

You'll save more money the more it's turned off.

Whilst it is true the unit uses more power to start, this is a tiny increase compared to it being on continually. (There's a starter that stores up the extra energy to start the tube)
Perhaps if you were rapidly & repeatedly turning the light on & off you may use more power, but generally, the more it is off, the less energy you will use.

Many offices, that also use flourescent tubes, now have automatic sensors to turn off lights when no one is moving. (or just moving their fingers on a keyboard )

melbury

Premier wrote: »

You'll save more money the more it's turned off.

Whilst it is true the unit uses more power to start, this is a tiny increase compared to it being on continually. (There's a starter that stores up the extra energy to start the tube)
Perhaps if you were rapidly & repeatedly turning the light on & off you may use more power, but generally, the more it is off, the less energy you will use.

Many offices, that also use flourescent tubes, now have automatic sensors to turn off lights when no one is moving. (or just moving their fingers on a keyboard )

Thanks (I think) for your reply.

However, surely it wouldn't cost very much to run that one tube per day, would it?

Premier_2

70 watts x 24 hours = 1.68kWh

Each kWh costs about 12p, so about 20p per day (over £70 per year! :eek:)

Farway

melbury wrote: »

Thanks (I think) for your reply.

However, surely it wouldn't cost very much to run that one tube per day, would it?

Depends how long your day is of course

Ten hours would be 700 watts [70 x 10], if say your cost per unit [kwH] is 10p then it is 7p a day, approx 50p per week, £2 per month, very roughly £25 per year inc VAT etc

melbury

Premier wrote: »

70 watts x 24 hours = 1.68kWh

Each kWh costs about 12p, so about 20p per day (over £70 per year! :eek:)

OMG I can't tell him that and it was him who suggested I ask the question on this site:eek: How can I delete this thread???:rotfl:

melbury

Farway wrote: »

Depends how long your day is of course

Ten hours would be 700 watts [70 x 10], if say your cost per unit [kwH] is 10p then it is 7p a day, approx 50p per week, £2 per month, very roughly £25 per year inc VAT etc

Oh that sounds much better. It is definitely not on for more than ten hours per day, probably less than that, so we are only talking a few pence here, so I think I win:T

Pincher

I have a £12 PIR sensor on the ceiling, works a treat.
The best part is when I leave the kitchen, after raiding the fridge, my hands are full, but I don't have to switch the light off.

melbury

Pincher wrote: »

I have a £12 PIR sensor on the ceiling, works a treat.
The best part is when I leave the kitchen, after raiding the fridge, my hands are full, but I don't have to switch the light off.

I have never heard of that, will have to look into it. Presume you mean the light comes on and goes off when you walk in and out of the room?

macman

Another vote for a PIR sensor. I have the same in the kitchen but it's built into the switch.
It doesn't go off when you walk out, it's set on a variable time delay.

[Deleted User]

Premier wrote: »

70 watts x 24 hours = 1.68kWh

Each kWh costs about 12p, so about 20p per day (over £70 per year! :eek:)

12p per kwh?:eek: we pay less than 9p