Can anyone give me a rough off-the-cuff estimate of how much ot costs
(approximately) to run a 60 watt bulbs for six months, non-stop?
(using an average-priced domestic electricity supplier)?
On Sat, 13 Dec 2003 14:57:49 GMT, firstname.lastname@example.org (Allan) wrote:
60W= 0.06kW. Per day the charge would be 24 x 0.06 x [the unit
charge for electricity]. Assume 10p per unit (it's on your
electricity bill) then 24 x 0.06 x 10 = 14.4p per day.
Six months is about 182 days so 14.4p x 182 = about GBP26.
Substitute your own unit charge for electricity if it differs.
Units are charged per Kilowatt hour, so for every 1000 watts (a kilowatt)
you use, you're charged for 1 unit of electricity. Therefore, a 60 watt
lamp would have to be on for around 17 hours to run anywhere near 1000 watts
worth of electricity. So a 60 watt lamp will use 1 and a bit units of
electricity per day if left on continuously.
This being the case M' Lod, 6 months is roughly broken down to 183 days.
The said lamp has been on continuously for those 183 days, using
approximately 1.2 units of electricity per day. Therefore, the said lamp
has used around 219.5 units of the electricity supplied to the house.
If each unit of electricity is charges at 6 pence, then the lamp will have
taken approximately £13.17 worth of the electricity.
Easy, eh ?
Not quite; for every 1000 Watts used for a period of one hour.
You can't /use/ a Watt - a Watt is itself a rate of energy
conversion (=one Joule converted every second).
But the rest of the calculation is fine.
I'm sure you *meant* to say that a 60 watt lamp would have to run for around
17 hours in order to use 1000 watt-HOURS of electricity (rather than watts).
A watt-hour (or Kilowatt-hour) is a unit of energy - and is what we get
billed for. Watts simply relates to the RATE at which energy is being
consumed. A 60 watt bulb can *never* consume electricity at a rate of 1000
I hope that clears up any confusion. [The answer was right anyway, even if
the terminology was slightly lax!]
Oh I'm sure it can... It's only rated at 60 watts when used at its
nominal voltage (probably either 230v or 240v). Outside this range
things change... but it almost certainly wouldn't last long enough to
measure the power consumption reliably if you got it to take 1000
email@example.com (Matt Beard) wrote in message
Sometimes when bulbs blow they take much more - briefly.
More importantly, 2 things were left out of the calculation. First is
the cost of the bulb(s), which is often minor, and often not.
182 days x 24 hours = 4368 hours = 4.4 bulbs.
At 20p each (with basic bulbs) thats another 88p.
But at £1:50 each thats another £6:60, taking us to over £20 all in.
Now, here's the more useful bit: the cost of a CFL.
Bulb price £3:50, life 5000 hours. Bulb cost thus £3:08.
Electricity cost of 11w for 4400 hours = 11/1000 x 4400 x 6p = £2:90.
Thus all-in CFL cost is £5:98. Per light fitting.
The lamp appearance doesn't bother me at all - but I agree about
the light quality.
Having said that, we have them in most fittings. I've
experimented with a wide range of CFs looking for the best light
temperature. The best ones have been the Screwfix spirals, which
are pretty close to an incandescent bulb. But they are the most
poorly made CFs I've ever seen - about 20% of them literally
fall apart after 6 months (the case separates!).
We have about 30 of them installed around the house, stables and
garage, and routinely return boxes of them to Screwfix for refund.
makes vary, some are crappy, some are fine.
Appearancewise there are fancy ones, like globes and reflector lights
adn so on, theyre about £8 a pop, but even so work out at half the
cost of incandescents.
I think thats why they stopped doing them.
I use the GE ones that have only really just come out (called Mini-Tech or
something similar). They are only fractionally larger than a normal
lightbulb and have the same shape. Don't write off compact fluorescents
until you've seen one of these latest types, rather than those horrible
stick like things for 99p from Ikea. They even do candle types, although the
bulbs are still considerably larger than a standard candle and not suitable
for many (most?) light fittings.
Modern types are pretty yellow, too, and produce light not dissimilar in
temperature to an incandescent bulb. The only real disadvantage is the time
taken to warm up.
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