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Old 28th Apr 2021, 11:16 pm   #49
broadgage
Octode
 
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 1,754
Default Re: Crompton 60W bulb

Quote:
Originally Posted by duncanlowe View Post
I hope this isn't drifting too far OT, but the mention of woolies in regards to lamps takes me back. I looked after the light fitting displays. On display, fittings were always equipped with 15W bulbs to avoid the big electricity bill from so many being in use. But the life was noticeably rubbish, so I was forever replacing them. Now I know we would have only been paying 'cost to the store' as they were treated as shrinkage. But I wonder if the significantly longer life of say 40W would actually have been cheaper? Might even have saved a bit of money on other heating for the store?
Use of a 15 watt bulb instead of a 40 watt bulb is of course saving 25 watts, or over 1000 hours is saving 25 KWH.

5 pence a unit was about the going rate for many years, so saving 25 KWH was saving about 1.25 in 1000 hours.
The lamps were probably about 10 pence each, cost price, not retail.
The electricity cost therefore exceeds the lamp cost.

And remember that the 15 watt lamps might well have lasted their 1000 hours.
If 100 lamps are lit for 12 hours a day, then at least half a dozen failures each week are to be expected.
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