that does not preclude the possibility that nearly half of them may fail within the first few minutes of use
Only true if the 'better half' were to last almost the rated number of hours
Only true if the 'better half' were to last almost the rated number of hours
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Only true if the 'better half' were to last almost the rated number of hours
Once, in a lamp making factory, watched such lamps being made, the final stage was testing, where they powered up on a conveyor belt. They would remain powered for a minute or two, then a photocell would check they were still lit at the end. Any which were not, or were too bright, were rejected. The too bright ones, obviously with shorted turns in the coil.
Only true if the 'better half' were to last almost TWICE the rated number of hoursOnly true if the 'better half' were to last almost the rated number of hours
The 'better half' would all have to last no less than (not "almost") the stated average (median) lifetime.Only true if the 'better half' were to last almost the rated number of hours
The thing one has to understand about a median is that it tells one that half of the bulbs will last less than that median, but tells one nothing about how much less. For example, showing an extreme scenario, with just a few figures for convenience, a group of bulbs having survival times (in hours) of, say ...
999, 999, 999, 999 , 1000, 1000, 1000, 1000, 1000
... and a group with survival times of, say ...
1, 1, 1, 1, 1000, 1000, 1000, 1000, 1000
... both have a median survival of 1,000 hours, although all those in the first group survives for approximately 1,000 hours, whereas nearly half of those in the second group only survived for 1 hour.
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NO, you're thinking of means, not medians - see what I've just written to Harry
I hadn't seen #15
Yep, with almost all manufactured products, very early failures (e.g. 'straight off the production line') are relatively common - hence the 'bathtub-shaped' failure curves one sees (high early failure rate, then a long period of low failure rate, eventually becoming an increasing rate of failure in 'old age'). That's as true of light bulbs as it is of most other things (indeed, even including animal and plant reproduction, not just manufactured goods!)_
I don't think you mean #14 (which was written by yourself), do you?
dunno wot ya meenI don't think you mean #14 (which was written by yourself), do you?
dunno wot ya meen
It would be slightly odd if you "hadn't seen" a post which you had written yourself
Yes. I clean the lens every time I change the bulb, - so quite frequently! TBH, the lens doesn't get visibly dirty due to it's corner position and the fact that I don't roast meats or anything that tends to 'spit' fat.
Fortunately the oven housing unit was designed specifically for my particular oven. The unit is open at the rear of the oven and has a gap of maybe 4cm (?) x unit width that runs behind the kitchen unit/cupboard that sits above the oven before emerging at the top. However, my Neff oven seems to vent to the front, judging by the draught of warm air emerging from slots in the front face.
Most, if not all, of the oven lamps I've fitted over the decades have come from either Tootstation or Screwfix and were rated accordingly, although I can't remember checking specified working voltage - may have done. I would very much hope these sellers would source bulbs suitable for the UK electricity supply.
True but I suspect there's more to it. I'd be interested to know under what conditions the bulb manufacturer conducts lifespan testing. Ovens may be used at a variety of temperatures. Perhaps the tests are carried out in ovens set to a low temperature. For instance, I prove bread dough at 45C in my oven. Or maybe accelerated lifespan tests are employed where the results are open to (mis)interpretation.Indeed - and, as I often remind people, even 'worse' than that, since average lifespan quoted is invariably a median, not a mean - which means that, even if the average (median) life expectancy ins genuinely hundreds (or even thousands) of hours, that does not preclude the possibility that nearly half of them may fail within the first few minutes of use
You are so right. There are far too many soul-sapping time-wasting chores these days, so I'm with you. I'll never blow another oven lamp in my conventional fan oven again because I don't have one fitted.
PS The bulbs I've fitted in my ancient microwave oven last many, many years (maybe averaging 10+ years?) though I doubt it ever gets as hot as a conventional oven bulb.
Thanks all for your input. Over and out.
The lamps, from self generated heat, will be much hotter than the oven..
All true.
My comments about claimed life expectances related to bulbs (and most other products) in general, but oven bulbs are a very special case snce, as you imply, they operate under pretty adverse environmental conditions. I'm not even certain that these bulbs are produced only for use in ovens. If not, it's possible that they are not tested under conditions any more extreme than are any other bulbs!
Of course, even if it were mean, rather than median, expected lifetimes that were being quoted, there would still be some unlucky people who who would experiences very early failures (balanced by others who enjoyed extremely long bulb survival times).
There is at least one practical reason why medians, rather than means, are usually quoted. To estimate the median, one only has to continue the test until half of a batch have failed, but to get an accurate estimate of mean, testing has to continue until the very last bulb has failed, which could take many years! There are often attempts to conduct 'accelerated testing', using adverse conditions, but one can never really know for sure how the results of such testing will compare with real-world in-service behaviour.
I thankfully do not have an issue with bulbs blowing but I would like something brighter than 15w I know you can get them brighter but they are a bit bigger and wont fit in the lens.
Shame they cant make LED ones because I have 8 LEDs lighting up a 4m x3 m living room that added up are only just more than a single 15w that lights a 0.4mx0.3m oven space. Crazy
Shame they cant make LED ones because I have 8 LEDs lighting up a 4m x3 m living room that added up are only just more than a single 15w that lights a 0.4mx0.3m oven space. Crazy
LED's, the electronics, simply would not be able to work with the temperatures found in an oven. One solution, would be to have the LED remotely mounted, somewhere cooler, then use light-pipes or fibre optics, to get the light where needed.
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