Light bulb longevity

[Dave2002]

I recently had to replace two low energy light bulbs, which were used for outside lighting. As I did so, I looked at the box of one of the bulbs I used as a replacement - which was similar to one which had failed - and noticed the claim that it would last for 10,000 hours. I normally take such claims with a bag of salt, but I thought I'd calculate how long 10,000 hours actually is, and it comes to 416.67 days approx, or 1.14 years. OK - the bulbs probably were installed for a bit longer than one year, but the claim is presumably made for operating time, when the bulbs are lit, and it's very unlikely that the bulbs we had were on for more than 20% of the time, and most probably less than that - say 10%, so they should have lasted for a good few more years.

I'm guessing this is normal - that the manufacturer's claims are so exaggerated that they become almost meaningless in practice. I did however wonder what would happen if I contacted the manufacturer and complained, though it's probably more trouble than it would be worth.

[Beef Oven!]

I did however wonder what would happen if I contacted the manufacturer and complained

Go for it!

[Frances_iom]

I assume they are the compact fluorescent type - these are prone to failure with repeated switching (eg if using a PIR sensor to switch on/off - likewise for repeated short term use such as in passageways) - the early lamps could also show high failure if the lamp got too hot usually due to poor lamp fitting design or placement in confined spaces. I've had early 2D fittings last over 10years tho the light output declines with time.
The new LED fittings would seem to offer improvements in both these areas but as in any rapidly developing technology the early entrants often do not live up to expectations as previously unrecognised failure modes make themselves known.

ETA another common cause of problems is surges on the powersupply - maybe less common in UK cities but much more common in more rural (+ it seems esp North American) systems with long cable links.

[Flay]

Well my life expectancy is 79 but

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[Nick Armstrong]

I'd just chip in that a series of 16 or so halogen lights was installed in the hallway here in 2000 - I think only 2 or 3 have failed since then! OK the hall lights aren't left burning for long periods but I still reckon 14 years and counting is pretty damn impressive!

[Gordon]

I'd agree with Frances. The claim of 10,000 hrs is supported by some industry defined test and it wll probably be based on a long period of being on wth perhaps a short on off cycle. It is tuned for maximum value!! I don't know of the standard but perhaps googling will find it. You will find that any lamp bulb will last longest if left on all the time but that has obvious consequences which are less with a CFB than an IB. If the lamp company doesn't get you the power company will. Disposal of CFBs has issues. Our experience with CFBs is that they fade quickly ie light output decreases over a period of a few weeks of normal use - on a few hours in evening, off all day - and as they get older they take a while to strike and come up to full brightness.

[johnb]

A couple of years ago the CFB bulbs were looked at in the Radio 4 programme "More or Less" and one of the things that was examined was the claim that CFBs are five times more efficient than incandescent bulbs, i.e. a 20 watt CFB is equivalent to a 100 watt IB. It turns out that these calculations are made using coated IBs. When compared to clear or pearl IBs the correct ratio is 3:1, i.e. a 20 watt CFB is equivalent to a 60 watt pearl or clear IB.

[Angle]

It's all very illuminating. I tried hard not to say that.

[Nick Armstrong]

It's all very illuminating. I tried hard not to say that.

Angle: poise, light - just what we've come to expect from you

[Dave2002]

I'd just chip in that a series of 16 or so halogen lights was installed in the hallway here in 2000 - I think only 2 or 3 have failed since then! OK the hall lights aren't left burning for long periods but I still reckon 14 years and counting is pretty damn impressive!

Halogen .... Aaagghhhh - Often the minimum is around 30 Watts, so you may be using around half a kWatt turning them on. We have the same in our kitchen, with a run of 8 and a run of 3 plus one other bulb - but I try to keep them off as much as possible. One "solution" we had to the high consumption was to fit high level fluorescents above cupboards - and that worked well for a while - until one day one or other failed, and I couldn't work out how to get the "system" working again. Unfortunately, the person who'd fitted them was unavoidably detained and unable to return to get them back into working condition.

I may have another go at doing it myself eventually, but that must have put our consumption right back up again.

I replaced all the halogen lights in our conservatory by LEDs - at vast expense - not just because of the energy cost, but because the halogens tended to get very hot, and subsequently became impossible to remove for replacement, thus ruining the fittings. I don't think this will be an issue with the LED lights, because they run a lot cooler.

[Frances_iom]

undercounter small fluorescent tubes are often wired daisy chain manner (usually with a two wire arrangement as they are dual insulated) tho fed in parallel from the mains - a failure of a connection will of course leave one or more lamps not working - switch the halogens over to 5W leds(I'm assuming GU10s main fed lamps) assuming you can extract them from the socket tho probably easier to replace complete fitting (check re fire regs as you may need to have some form of protection against fires in a ceiling void but new fittings that meet all modern regs are not that expensive when bought from trade suppliers) - make sure you buy the latest LEDs as some of the early ones were not very efficient - a cool white is brightest though you may prefer a warmer white - a non dimmable LED is usually about 20% cheaper .
I replaced my old 5ft fluorescent strip light in the kitchen with a surface mounting LED 4ft fitting - instant turn on + bright light - likewise in my cellar workshop installed 600mm sq panels over the benches (replacing spots) giving a much better + more uniform light without the previous problem of always working in one's own shadow - not however a cheap option as panels typically about £100

[teamsaint]

we did this thread and all its associated terrible jokes, (watt no puns) last year.

What does for lamps of any kind is heat and vibration, which is why upstairs lamps tend to last longer.
So the answer to some of our longevity problems is to avoid heat and vibration upstairs.

Which seems sadly counter intuitive.

I really hope S_A joins in this thread soon.

Edit: I wonder what the explanation for Rumpole's long lived lamps can be..............

[Dave2002]

Frances

I think these strip lights from IKEA might be quite good - and suitable for the high level lighting application I mentioned - http://www.ikea.com/gb/en/catalog/ca...ated_lighting/

We have some of these which I've very recently tested, as I'm trying to fit them into some new wardrobes. They appear to give a good light, and the strips have an auto function which to my surprise seems to work quite well for applications where there's a door which opens.
For other applications simply turn the switch to manual, and control the lights by the on/off switch or power switch. It might be necessary to use multiple strips if the light level from one strip is insufficient. There may be other products coming along which would be better, but these are at least going in the right direction,

I've tried various LED lights over the years, and until recently many gave an unpleasant light, but there do now seem to be some lights which are reasonably suitable for a range of applications.

[Sydney Grew]

. . . I replaced all the halogen lights in our conservatory by LEDs . . .

That sounds like a good idea and I will try it in future, thank you.

As it happens I have a box literally within arm's reach. Upon it I read, and from it transcribe:

Halogen Globe
30% Energy Efficient
The halogen globes last for twice as long as incandescent globes
Our Promise: 100% satisfied with this product or return it to your Coles customer service desk for a 100% refund.
Made in China
2 year globe life (based on average use of 3.3 hours/day. Actual life may vary in individual circumstances.)

I think the catch there - which has not yet been mentioned - is that "average use of 3.3 hours per day." In my actual experience bulbs in the kitchen or living-room seldom last longer than three months. That is, they last no longer than the old incandescent ones, and cost three times as much. This is the capitalist way is it not?

[Beef Oven!]

That sounds like a good idea and I will try it in future, thank you.

As it happens I have a box literally within arm's reach. Upon it I read, and from it transcribe:



I think the catch there - which has not yet been mentioned - is that "average use of 3.3 hours per day." In my actual experience bulbs in the kitchen or living-room seldom last longer than three months. That is, they last no longer than the old incandescent ones, and cost three times as much. This is the capitalist way is it not?

Chinese captialism?