Long Life bulb wanted

[bernardgreen]

Forget LED lamps if you want long life from your lamp

http://www.centennialbulb.org/

 

[ericmark]

Interesting started at 60W now using 4W has a carbon filament. I would guess if we took any bulb and put so little power through it then it would last a long time, it would seem for what ever reason the filament resistance has increased to a point when it used so little power it does not degrade any further.

I am sure there are some indicator bulbs which have a very long life, not over 100 years as likely the equipment has not lasted that long, I look at my living room and the DVD player has a little red LED showing there is power to the unit which has likely been on from day it was bought so 15 years old. Although the neon on switches do fail, bet there are some very old ones.

Now had the bulb still been taking 60W then that would be truly amazing. But 4W through a 60W bulb likely will last until building falls down.

 

[Adam_151]

I'm with Eric, I'm not sure thats its anywhere as amazing as people seem to think, with todays manufacturing technology we could make any number of almost ever lasting filament lamps, we don't because the lumens per watt figures wouldn't be much good at all, overall its much better to have to replace it every 1000 hours. They do make some which are a bit of a compromise... long life and rough service lamps for where the replacement is a difficult operation or vibration would lead to premature failure of a normal lamp. Interestingly about five years back when they were phasing out GLS lamps and pushing the ones with a halogen capsule inside for reasons of efficency, if you asked for a standard GLS lamp, the wholesaler would hand you a rough service one, as being a special purpose lamp they were exempt from the new red tape, so now they got used in places where they wouldn't otherwise and efficeny was decreased rather than increased

 

[bernardgreen]

The everlasting filament is possible. But when you read the history of the company you find information about an agreement to make filaments that were not everlasting. This wa necessary otherwise sales of lamps would slow done onec every one had bouth all the lamps they needed. This is likely to have been the first major instance of Built in obsolence.

 

[bernardgreen]

. But 4W through a 60W bulb likely will last until building falls down.

I am nit certain but I believe the lamp has been wearing out and it has itself changed from 60 watts to 4 watt by slow erosion of the carbon filament and thus increasing the impedance of the filament.

 

[JohnW2]

Forget LED lamps if you want long life from your lamp...

Indeed, other than that the article describes it as the "Longest Burning Light Bulb"

Whilst that one may be the bulb/lamp that has been in the longest more-or-less 'continuous' service (about 117 years), there are much older ones than that which are still working, although I don't know how much they have been used. For example, this one was still working in 2013, about 130 years after it was made (in 1893) - and if it's still working today, that would be about 135 years.

Kind Regards, John

 

[ericmark]

As I understand it bulb life is worked out by how long it takes for 50% to fail, it is accepted some will have a shorter life and some a longer life. So one can't work out bulb life from a single bulb, so once 50% have failed that's it, even if one odd one in the batch lasts 10 times longer.

 

[JohnW2]

As I understand it bulb life is worked out by how long it takes for 50% to fail, it is accepted some will have a shorter life and some a longer life.

Yes, that is one of the most common, and very simple, statistic used as an index of lifespan for things, particularly consumer products - mathematically it is simply the median time to failure. The other fairly common approach is to use statistics such as MTBF {mean time between failures}, more for 'non-consumer' purposes).

A similar concept is used to specify an 'average' effective dose a medicine or an 'average' amount of a toxin required to do harm (e.g. kill!) - ED50 is the dose of a medicine which is effective in 50% of those to whom it is given, and LD50 (LD=lethal dose) is the amount of a toxin that will kill 50% of people/animals/bacteria/plants to whom/which it is given.

When, as very commonly the case, the 'survival curves' are far from linear (over time/dose or whatever), these statistics based on median values are generally much more useful/meaningful than those based on arithmetic means ('ordinary average'), since a relatively small number of extreme (low or high) values can seriously distort the latter.

Many things (including human beings and light bulbs) show what is often described as a 'bathtub'-shaped survival curves - with a very early high 'failure' rate, followed by a period of low and relatively constant 'failure', after which failures/deaths progressively increase with time. In terms of human life expectancy, when, a few years back, I did some research into my family history, I was struck by the fact that, even 300 years ago, most of my ancestors and their families who survived to adulthood lasted for more-or-less the same amount as people do today - i.e. most dying between about 60 and 85 - despite the fact that 'average' life expectancy was dramatically lower back then (indeed, even the Bible speaks of life expectancy as being "three score years and ten"). The reason, of course, is that there was a very high rate of infant and childhood mortality, which dramatically pulled down the 'average' over all people that were born.

The same is true of most manufactured goods (including lightbulbs) - the average lifespan of those which survive the first few minutes/days/whatever is generally much higher than the 'overall average' which includes those early failures.

So one can't work out bulb life from a single bulb, so once 50% have failed that's it, even if one odd one in the batch lasts 10 times longer.

That's obviously true. There is nothing 'statistical' one can determine by just looking at 'a sample of 1' - which, as you imply, could just be a fluke, totally unrepresentative of how bulbs in general might behave.

Kind Regards, John

 

[ban-all-sheds]

For example, this one was still working in 2013

Nobody who thinks that "The new eco bulbs take all week to warm up" has any credibility in the matter of understanding the passage of time.

 

[JohnD]

The reason, of course, is that there was a very high rate of infant and childhood mortality, which dramatically pulled down the 'average' over all people that were born.

The first few days of life are among the most dangerous.

The last few are even worse.

 

[JohnW2]

The first few days of life are among the most dangerous. ... The last few are even worse.

Both true. However, whereas the start of "the first few days of life" is well defined, ascertaining when the start of "the last few days of life" is going to occur requires a crystal ball.

Of course, in terms of what I was talking about in the bit of my post you quoted, "the first few days of life" and "the last few days of life", can be very much the same think, hence equally 'dangerous'!

Kind Regards, John

 

[ban-all-sheds]

ascertaining when the start of "the last few days of life" is going to occur requires a crystal ball.

Or a foolproof plan and some kind of weapon.