Moving Spirals in Fluorescent Lamps? and more...

[Alla Musica]

Hi all,

I guess most of you have seen some moving spirals in some fluorescent lamps. Not sure if there's a better description for that, but with my keywords I don't seem to find any relevant explanations online or elsewhere on this forum.

I have an emergency lamp with T5 6W fluorescent lamps and a 6V lead-acid battery. Sometimes the tubes act in the above way when illuminated. Is it a sign that the tubes are increasingly closer to failure?

Also, upon startup the tube ends get very dark, which subsequently fades away as the tube continues to illuminate. Does that imply any problems with the ballast etc.?

Best,
Chris

 

[littlespark]

Black ends on tubes are a sign of near failure of the tubes....

The spirals you see.... are like brighter points of light moving slowly along the tube?
Its a sign that the control gear for the light is failing... and even if you change tubes, the problem will just burn out the new tubes prematurely.


New LED emergency lights are very cheap... I'd advise having them changed

 

[Alla Musica]

Many thanks for getting back, mate.

The spirals you see.... are like brighter points of light moving slowly along the tube?

I would say... quickly.

The spiral movement don't persist though (it's very occasional) - they just slow down and show up on the tube, stay still for a short while, accelerate again and vanish in a blur.

You said "brighter points" - technically, YES, but I would say it's very faint - to such an extent that if you don't stare at the tube directly, it makes no difference in fulfilling its lighting function.

I'd advise having them changed

It's different from those maintained / non-maintained fixtures in the UK. It's just a very old portable battery lamp (fluorescent-flashlight combo) that I'm always taking care of as a vintage item.

 

[Alla Musica]

In case of your curiosity

 

[littlespark]

ah.. i see... not the same as what i was thinking.

just old age i guess..... your light, not me

 

[Alla Musica]

just old age i guess.....

Welp, yeah - thanks anyway!

 

[Ian Malone]

Hi all,

I guess most of you have seen some moving spirals in some fluorescent lamps. Not sure if there's a better description for that, but with my keywords I don't seem to find any relevant explanations online or elsewhere on this forum.

I have an emergency lamp with T5 6W fluorescent lamps and a 6V lead-acid battery. Sometimes the tubes act in the above way when illuminated. Is it a sign that the tubes are increasingly closer to failure?

Also, upon startup the tube ends get very dark, which subsequently fades away as the tube continues to illuminate. Does that imply any problems with the ballast etc.?

Best,
Chris

Tube needs changing as the chemicals inside have gathered at end. These Lamps do not have a very long life unlike the old light bulb. Also what everthe new lamp says it has in lamp hours, it will be very dependant on environmental conditions . Really time for new fitting.

 

[Alla Musica]

Tube needs changing as the chemicals inside have gathered at end.

Oh no... does it matter if, only upon startup, the chemicals just gather there for a short while and then disappear as if nothing had happened?

 

[Marvo]

The way fluorescent tubes work internally is surprisingly complex. You can change the nature of the light output by disconnecting the earth (especially so with a steel batton type fitting) or even just laying your hand on the outside of the tube whilst it's lit and this is due to changing the capacitance of tube to earth or ground. Differing ambient temperatures and humidity can also have a similar effect.

With that type of emergency light you have there's also often problems caused by a cheap internal inverter which may have an unstable output or unorthodox shaped output waveform or both. It will be that inverter providing inadequate heating that's causing discoloured ends of the tube on start up.

 

[Alla Musica]

.With that type of emergency light you have there's also often problems caused by a cheap internal inverter which may have an unstable output or unorthodox shaped output waveform or both. It will be that inverter providing inadequate heating that's causing discoloured ends of the tube on start up.

Thanks very much for your kind suggestion. Really - it is most likely to do with a very flimsy cold-cathode-start inverter, as the tubes barely become hot even after hours of illumination.

High five!