How long do bulbs last? Tungsten, CFL, LED etc.

[SUNRAY]

It's a compromise - a light bulb can be made to last almost forever, but that would not be very efficient, light output, versus power input. So the agreement, was a matter of agreeing a figure for life, versus efficiency of light output.

When I was at high school based in a very old mansion house we measured the building to make a scale model but one wing the room dimensions didn't match the footprint, judging by window positions we concluded there was another room off of the deputy headmasters office behind built in cupboards, to cut a story short the odd job man cut a hole in the wall to find a room of some 10-15m² and the light was on. One of the teachers had been there for decades and said it had not changed in his time. There was also a window covered with ivy but the glass and the light were so black it wouldn't have been visible for years

 

[ebee]

Well we get into mindsets, fueled by rules of thumb, old wives tales and folklore, urban myths and the like, including me.
I have worked on such a rule of thumb/urban myth for years.
All lamps (generally ) receive stress by being switched on or off and this must be considered before operating.

With purely incandescent filament lamps stress is increased and a possible cause of premature lamp failure therefore if we decide to actually switch a lamp on that is one stress added, leaving it running stresses it a bit during the on period, switching it off adds another stress. That is just one cycle.
There comes a point where we should consider the consequence of multiple switching operations causing undue stress and the effect it has on lamp life.
Some work on the theory that leaving a lamp on rather than switching off for a period of 20 mins or less (or 30 mins or less or whatever) then is it worth it?
Balance that against costs of power drawn cost and cost of replacement (include labour time of actually replacing it and time lost of an increase of time to do the job in hand). We might also include losses therefore expense of extra power drawn at switch on time and the warm up period too.

Fluorescents - a business I was allied to for many years, first person in the shop in the morning switched all the lights on and the last person out switched them off - they operated the main switch on the lighting consumer unit to achieve this simple task.
Their fluoro tubes lasted for years and years. No idea what their electric bill was.



16 or 28 watt 2D bulkhead fittings I installed for customers, two or three were having low lamp life, I noticed switch on periods of a few minutes or even a few seconds and the next such operation was never much later on either. I suggested the 20 minutes rule and the problem apparently disappeared.

LEDs - I have no idea, not even strong suspicions really.

Therefore I have always worked on the 20 or 30 minutes rule.

I do remember one job where I was feeding a cable between floors - poke end thru the floor then go downstairs to grab and pull and by the time I got there (a few seconds) the householder had gone to switch the light off therefore I had to go back upstairs to switch it back on and ask him to leave it alone.
He had the habit of doing this every time with every workman in the house, he was a right pain in the neck with all of those and some warned him he was causing extra labour costs because of his actions.
I noticed that older generations of folks had more of a tendency to be overly adept at switching off and vice versa for the younger ones.

PS - as an aside, because of my need to remove drawers from cupboards to move them then replace drawers then I also got used to a rule of thumb that almost all people over a certain age had a drawer or drawers absolutely full of various oddments of neatly folded brown paper and or various oddments of varying lengths and types of bits of string.
In fact, if I did not notice it in a very few of them then that fact stood out like a sore thumb.

I will not mention "Old Person`s Knives"

 

[Harry Bloomfield]

PS - as an aside, because of my need to remove drawers from cupboards to move them then replace drawers then I also got used to a rule of thumb that almost all people over a certain age had a drawer or drawers absolutely full of various oddments of neatly folded brown paper and or various oddments of varying lengths and types of bits of string.
In fact, if I did not notice it in a very few of them then that fact stood out like a sore thumb.

We have several of those drawers, around the house. The worst of which, is the one in the kitchen - it has plastic containers of drawing pins, map pins, elastic bands, key marker fobs, buttons, an emergency plugged in to the line phone, a box of throwaway lighters, box of marker pens, and a couple of hundred nearly new pencils.

The pencils are ones Avril has brought home, from the school she works at - if pens or pencils fall on the floor, the pupils are not allowed to pick them back up..

Garage, workshops and hut are a different matter, full of useful junk.

I will not mention "Old Person`s Knives"

Go on, what about them?

 

[Sureitsoff?]

The pencils are ones Avril has brought home, from the school she works at - if pens or pencils fall on the floor, the pupils are not allowed to pick them back up..

Why not? And who made that stupid decision???

 

[ebee]

We have several of those drawers, around the house. The worst of which, is the one in the kitchen - it has plastic containers of drawing pins, map pins, elastic bands, key marker fobs, buttons, an emergency plugged in to the line phone, a box of throwaway lighters, box of marker pens, and a couple of hundred nearly new pencils.

The pencils are ones Avril has brought home, from the school she works at - if pens or pencils fall on the floor, the pupils are not allowed to pick them back up..

Garage, workshops and hut are a different matter, full of useful junk.



Go on, what about them?

It seems to be everybody over a certain age has a knife or three of the old fashioned type with a handle of bone china or bone or indeed plastic that looks like bone and made to its own distinctive shape as well, not much like the more modern metal ones. In fact we always have about three of those "Old Persons Knives" and are favourite for butter bread etc there are loads of them in second hand shop and we gave them their nickname many years ago, they might even have a real name that distinguishes them. But anyway some of the older folks had loads of them, hence our nickname. Daft innit? LOL.

My favourite is the one we have with a blade that`s about twice the width of the others.

 

[Harry Bloomfield]

Why not? And who made that stupid decision???

I guess it maybe came in during covid, and just stuck. They claim schools are short of funds, but they chuck an immense amount of stuff away, including perfectly good furniture etc.. Last week, they were chucking a good as new filing cabinet away, that is now in my workshop, as storage for power tools. A perfectly good Henry, now keeps my workshop clean.

 

[ebee]

Might be Ryanair that reportedly instructed all their employees to nick as many pens and pencils as possible during seminars at hotels and exhibitions

I always made a point to come away from such with loads of pens (sometimes hundreds) from ELEX shows and the like. In fact on a Nile Cruise a few years back I kept getting my pens confiscated by police, boarder guards etc, everywhere you went if you had a biro etc they wanted it, soon learned they were valuable to them because they had trouble getting them for some reason. So then we learned to barter pens after a haggle to reduce the price more

 

[Harry Bloomfield]

In fact we always have about three of those "Old Persons Knives" and are favourite for butter bread etc there are loads of them in second hand shop and we gave them their nickname many years ago, they might even have a real name that distinguishes them.

Got it now, we have a couple in the cutlery drawer, and as you suggest - perfect for buttering bread. From my youth, I half remember them being the normal knives to eat dinner with.

 

[ebee]

Yup thats it Harry, I bet a few of us have one or three, what do other folks call them?

 

[ericmark]

All lamps (generally ) receive stress by being switched on or off and this must be considered before operating.

LED bulb just fitted says Lifetime 25,000 hours On/Off 15,000 so yes LED's should not be switched on/off too many times.

But 25,000 hours seems a lot, when compared with the 1,000 hours agreed between the wars. however my living room lights auto come on at dusk, and in case we forget to switch them off, auto off at dawn. Wife tends to stay up into the small hours, so average use per day around 7 hours, so just under 10 years life, going by the sales info. However the life is when half the bulbs have failed in a test batch, so before they can give that figure lights would need to have been lit 3 years, rather than the old 1½ months, so it seems unlikely bulbs are tested to give true life.

So random looked at a bulk head integral lamp, life 35,000 hours, so yes add says lasts longer, so now looking at 5 hours use per day nearly 20 years, by which time ½ should have failed, yes the law it seems says products should be supported for 7 years, but a year ago fluorescent fittings were still on sale, so tubes should be made for another 6 years, we know that is unlikely to be the case, so what are the chances even in 10 years time to get a matching replacement for an integral lamp?

I go into the doctors surgery waiting room and look at the 2D lamps on the ceiling, no two look the same, clearly fluorescent tubes replaced with LED versions, but no two LED replacements look the same.

As to knifes, I remember when around 10 years old, meeting my uncle going to a reunion meeting of the black watch, and looking at the dirk in his sock, and as a scout I was proud of my double shife knife, never really used it, it was not part of uniform, but nearly every one had one. This was reduced in latter years to the swiss army knife, which was far safer than the the Stanley knife, which seems to be what we are limited to today.

 

[SUNRAY]

Why not? And who made that stupid decision???

I did some work in an office block, a wine company had 2 floors. On the way to the plant rooms I was shown the 2 'kitchen areas' where copious supplies for hot and cold drinks were freely available including boxes and boxes of company mugs. After being shown the plant room it was suggested I grab a coffee while my PC downloaded the data. Heading back for another drink an hour or two later I was told by a member of staff the mugs were out of date/previous publicity items and we were not permitted to wash up or use a dirty mug and shown the 'bin' where they are dumped AFAIWC that was silly and they went in my toolbox.

 

[Harry Bloomfield]

Since changing the most used lamps to LED, I have suffered zero failures, except for one fitting. That an outdoor lantern fitting, on at dusk, off at 11pm. That went through two LED lamps, until I arrived at the conclusion that it was running too warm, in the enclosed space, so I added some ventilation - since when, the LED lamp has lasted for years..

I should have kept my mouth firmly shut....

I bought 3x dimmable 8w LED lamps, about 30 months ago from Screwfix, to replace the rather too dim 3.5w dimmable LED's, that I had put up with in those locations, for many years. Three BC wall lights. Two, of the three have just failed, within 3 days of each other

 

[JohnW2]

I should have kept my mouth firmly shut.... I bought 3x dimmable 8w LED lamps, about 30 months ago from Screwfix, to replace the rather too dim 3.5w dimmable LED's, that I had put up with in those locations, for many years. Three BC wall lights. Two, of the three have just failed, within 3 days of each other

That obviously proves nothing, and doesn't actually sound too bad. Yopu don't tell us about location/usage, but if they averaged 4 hours per day, 365 days per year, that would be about 3.600 hours use.

As I always remind people, the 'average lifetimes' quoted for things like bulbs/lamps are invariably median figures. That means that if the quoted lifespan is (truly!), say, 10,000 02 20,000 hours, that in no way precludes the possibility that nearly half of them fail within the first few hours of use

 

[SUNRAY]

A few days ago I had to replace yet another LED in our hall, I think that's about 40 in the three 3 arm fittings (9 LEDs total), I think about 8 years

 

[Harry Bloomfield]

A few days ago I had to replace yet another LED in our hall, I think that's about 40 in the three 3 arm fittings (9 LEDs total), I think about 8 years

The wall lights have tight glass shades, only open at the bottom, which probably helps trap heat, and as we all know, it's heat that kills LED's. I'm wondering, if I should rotate the lights 180, so they are open at the top, might enable them to run cooler.