Why do T5 Tubes in Emergency Luminaires Wear Out?

[Eschatonic]

LO All,

The title says it all really.

I've just tested a shed load of 11 year old emergency lights and effectively all of them have failed or failing tubes.

Since the most that they should have been on is 11 x 1 hour and 1 x 3 hours per year why would a 5000 hour lamp fail?

After 11 years I expect all of the NiCd battery packs to be shot but the lamps surprised me.

Any ideas amigos?

 

[telectrix]

old age? seriously, are thes EMs maintained? if so the lamp life will be weeks instead of tears.

 

[Wonderwall]

I can't think why an eleven year old lamp may fail.
Have you thought of taking them back. It's outrageous

 

[NDG Elecs]

If it's defo the tubes themselves then I can only presume a bad batch was manufactured. Maybe gases have slowly leaked out over time. Dunno..

 

[Deleted member 72666]

If the tubes failed to strike then it could be the control pcb in the fittings themselves that are faulty but as you haven't elaborated it's hard to diagnose from afar.

 

[snowhead]

Personally I wouldn't waste any Brain cells thinking about them.

Just change them for LED fittings and expect to change those in 10 years as well.
Nowadays nothing lasts, let alone lasts forever.

 

[Simonslimline]

You can test the tubes with something like this.

https://www.youtube.com/watch?v=2hwCg-IycP8

 

[Lucien Nunes]

If it's definitely the tubes, i.e. new tubes work fine in the existing fittings, then I suspect faulty tube manufacture as tubes don't really have a shelf life and should run for decades of periodic tests. Tubes running on cheap low power inverters as in basic emergency fittings may have reduced lifespan but not as low as 150 hours.

I have seen sub-standard T5 tubes of two no-name brands supplied with 12V inverter fittings that failed after a short period, maybe 100 hours. They gave out a perfectly good light at first and would not have aroused suspicion in an emergency application for some years, but the ends began to blacken and then refused to strike. There was nothing wrong with the fittings as I replaced them with Sylvania tubes that have lasted for many years and still going strong.