small fluorescent tube life

[bof]

Anyone suggest what the life expectancy of a 12" 8W fluorescent tube should be? They seem to be lasting about 6months here with around 12hrs a day use, much less than standard 5' 58W tubes.

[Dave Osborne]

Osram: 4500 hours "service life", 8000 hours "lifespan".

Philips: Don't say.

GE: Warmwhite 5000 hours "rated life".

GE: Coolwhite 8000 hours "rated life".

[Dave Plowman (News)]

Probably down the to the driver. I've found those small tubes last as well as any other.

[NT]

I gather some ballasts do treat the tubes poorly.

NT

[bof]

Thanks, the current and previous tubes were Philips, but seems like there's a problem, I can only guess it's with the driver unit.

[bof]

In message , "Dave Plowman (News)" writes

Maybe I'll try another unit, see if there's any improvement, though it may be cheaper just to keep feeding the current one tubes.

[PeterC]

Looking at small tubes (up to 20W) a couple of days ago, there was in some cases a factor of 2 between electric and electronic, with the latter being better.

[Andrew Gabriel]

Lots of possibilities. How do they die?

control gear can have two detrimental effects on tube life. Firstly, if it doesn't preheat the electrodes, these will wear significantly at each switch-on. If a tube is switched on for less than about 3 hours each time, tube life is generally limited by the number of switch-ons rather than operating period. Secondly, the current waveform (or more specifically, the "crest factor") has an impact on the electrode life whilst the tube is running. Good control gear has a low crest factor. Crappy high frequency control gear (such as in a cheap torch) often has a high crest factor and will wear a tube out quickly.

There are also lots of low quality tubes around in these sizes, where there are many uses such as emergency lighting where the tubes will never be operated long enough to reach end of life, so short life doesn't matter.

What sort of control gear (or fitting) is it in?

[bof]

In message , Andrew Gabriel writes

Bog standard (I assume) electronic mains powered surface mount white box, pretty non descript really.

[Andrew Gabriel]

Not enough info to provide a useful answer.

Most of these I see are still mains magnetic ballasts and a starter. Only tend to find electronic control gear in those with very slim bodies (similar profile to the tube itself).

[PeterC]

From limited searching, it would seem to be worth getting the electronic ballast as the life of the tube can be twice as long as with the old type of ballast. Old-type ballast are a bit like NiCd batteries: still hanging around although long superseded.

[Mike Tomlinson]

In article , Andrew Gabriel writes

Are they any good? Fitted an "Eterna" one from B&Q (intended for under- cupboard use in kitchens) in a display in a local pub a few weeks ago, it's probably on 12 hours a day, and has already failed.

[Andrew Gabriel]

I've fitted a few "Eterna"s, and no failures yet. I would not expect them to be same quality as Orsam, Philips, Tridonic, Helvar, etc ballasts, but it should last longer than that.

I fitted many of the Omnicron ones before they vanished. These fail to shutdown when the tube dies, and carry on running the tube in cold cathode mode, until the heat melts through the glass or makes the lampholder melt and drop the tube out (both of which have happened). I could imagine them starting a fire if fitted close to something combustable.

[Mike Tomlinson]

In article , Andrew Gabriel writes

Thanks. Have a replacement tube but not yet fitted it.

Yes :) I've used more expensive fireworks which lasted longer.

Lovely. One to look out for.