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)?
Thanks...
Allan
'Bout fifteen quid...
Si
At 6p/unit including standing charge for electricity, £15.72
.andy
To email, substitute .nospam with .gl
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 ?
A unit *is* a kWh.
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 watts!
I hope that clears up any confusion. [The answer was right anyway, even if the terminology was slightly lax!]
Peter, check your bill if your rate is nearer 10p rather than 5p/unit change supplier.
My god, it was only a simple explanation, not the Spanish Inquisition. :-))
Checking the bill would have involved disturbing the cat, there are standards :-).
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 watts!
Quite! [OK, "never" may have been too strong, but you will be aware of the point I was making in distinguishing between energy and power].
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.
Regards, NT
It's just a pity that the light that they generate gives a bilious appearance to things and that the lamps themselves are pretty ugly.
.andy
To email, substitute .nospam with .gl
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.
Plus the cost of three or four new light bulbs, unless you are running extended life bulbs.
Colin Bignell
Thanks for the rplies folks. The concensus seems to be approx £15. I was trying to calculate which would be most cost-effective: whether to install a PIR switch in my hall and another on my landing, to control the lights when movement is detected - or whether to buy two £12 light-senitive light fittings that use low energy bulbs that come on at dusk. I think I'll do the latter, since those PIR switches often don't even last a year before some power surge or blowing bulb fries the cirquitry. They cost at least £25 and are not intended for low-energy bulbs - whereas the dusk-to0dawn light sockets cost £12 each, accept low-energy bulbs and hopefully will last much longer... They also have a timer on them so that at dusk, they come on for
3,4,6, or 8 hours depending on how you set them.Thanks again
Allan
Most of the stand alone PIR switches are quite happy with any bulb - they have relay outputs. I've used two PIR's stripped from 500w floodlights (the cheapest way to buy them) controlling hall and door lights for 10 years each with no failures -one controls a low energy bulb, one a standard one. (I know its no really worth switching a 2D bulb in this way but the fitting was already there).
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.
Regards, NT
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