Household Incandescent bulb goes super nova!!!

[UVLaser]

The bulb in my brother's lamp burnt out. It was weird how it did, the bulb was running fine and out of no were it got brighter and after 3 or 4 hours(I was not keeping time here)it went out.
Did somthing special happen here? Why did it get brighter towards the end of its life? /ubbthreads/images/graemlins/confused.gif

Thanks a nickle /ubbthreads/images/graemlins/thumbsup.gif

 

[samauri11]

UV laser
I've seen it happen when a looping filament breaks off on one end, then reconnects in shorter section. Gives it a short but bright life like an over driven flashlight bulb.

 

[MaxaBaker]

The way bulbs blow ou tfor me most of the time is a very bright bluish flash when you turn it on. They always blow at the wrong times it seems. Scares me sometimes.


...click...BLINK/FLASH!!!!!!....Holy Crap!.....

 

[James S]

I would have to guess that 95% of the bulbs I loose are on startup, just like Maxabaker describes, but a few do interesting things like you describe. I've definitely had the broken filament weld itself back together slightly shorter and get brighter. That can definitely happen. Since I've started installing Home Automation stuff and automated light switches that can do a ramp on rather than just click/bang, I haven't lost a single light bulb. i know that I will eventually loose some, but the life span is definitely increased considerably when you do it that way.

 

[bobisculous]

I would think something like the filament came back together, or touched in some different way to the connectors or nodes, or whatever they are called.
I once, with a clear dead bulb, made it work again. I could visibly see the filament coming very close to connecting. I turned the power on to the light, then just tapped the bulb a few times. Once it touched, viola, light was restored once more. I think it went back out though as soon as I cut power to the bulb.
Fun to play with stuff like that.

Cameron

 

[PhotonWrangler]

I've seen this also; exactly as described, the filament welds itself in a manner that it shortens itself, running at a higher wattage and much shorter life.

What's scarier is watching a halogen lamp explode! I've seen instances where the lamp was vibrated while it was running (big no-no) and the hot filament briefly came in contact with the inner envelope, causing an eerie whitish-bluish-greenish progression of colors before it went pow! The whole sequence took maybe 4 or 5 seconds. That's what the footnote in the lamp catalog meant by a "non-passive end of life characteristic!"
/ubbthreads/images/graemlins/str.gif

BTW many, many fires in college dorms have been traced to halogen lamps.

 

[Mike Painter]

[ QUOTE ]
James S said:
I would have to guess that 95% of the bulbs I loose are on startup,

[/ QUOTE ]

Right. It takes more amperage to get it started then keep it going and this is one the reasons. The other seems to be that the filiment vibrates at start up because of induction and this can cause a mechanical breakage.

 

[RayT]

[ QUOTE ]
Mike Painter said:
The other seems to be that the filiment vibrates at start up because of induction and this can cause a mechanical breakage.

[/ QUOTE ]
I sometimes also vibrate at startup but mine is not induction based, but expulsion based.