light bulb explosion

[PatrickM]

Sorry if it's the wrong newsgroup but I've came here before so I thought of
asking here first...
Today in our home kitchen a standard 100-watts light bulb "exploded". It
happened just like that for no apparent reason, my girlfriend was in the
kitchen reading and could have been injured by the flying glass from the
bulb. The fuse didn't open. Has anyone ever seen or experienced something
like that before? Why would that happen? Thank's for any info and sorry for
my approximate english.

Patrick, from Quebec, Canada.

 

[Eric Lambi]

Over the years I have seen several light bulbs explode with a sea of broken
glass and sparks. I don't know why they went out in such a manner. One time
was in a underground hallway leading to the University of Saskatchewan
Library right in the middle of final exams! At the time I assumed it was
because of too much angst.

Regards,

Eric

 

[John Popelish]

Sorry if it's the wrong newsgroup but I've came here before so I thought of
asking here first...
Today in our home kitchen a standard 100-watts light bulb "exploded". It
happened just like that for no apparent reason, my girlfriend was in the
kitchen reading and could have been injured by the flying glass from the
bulb. The fuse didn't open. Has anyone ever seen or experienced something
like that before? Why would that happen? Thank's for any info and sorry for
my approximate english.

Patrick, from Quebec, Canada.

Light bulbs ordinarily have a low internal pressure (much less than
atmospheric pressure) so do not actually explode, even if the filament
overheats for some reason (like a partial short circuit). But the
glass can shatter from internal stresses (not properly annealed) or
from being splashed with water.

My parentheses keys are tired now.

 

[Terry Pinnell]

Sorry if it's the wrong newsgroup but I've came here before so I thought of
asking here first...
Today in our home kitchen a standard 100-watts light bulb "exploded". It
happened just like that for no apparent reason, my girlfriend was in the
kitchen reading and could have been injured by the flying glass from the
bulb. The fuse didn't open. Has anyone ever seen or experienced something
like that before? Why would that happen? Thank's for any info and sorry for
my approximate english.

Patrick, from Quebec, Canada.

In my less sceptical days I recall reading that exploding light bulbs
was a well known symptom of poltergeist activity. Were there also any
books seen flying across the room? <g>

As John said, bulbs should implode. But of course gravity then takes
over and 'flying glass from the bulb' would be a natural description,
especially from someone deeply immersed in a good book!

 

[Dr Engelbert Buxbaum]

Sorry if it's the wrong newsgroup but I've came here before so I thought of
asking here first...
Today in our home kitchen a standard 100-watts light bulb "exploded". It
happened just like that for no apparent reason, my girlfriend was in the
kitchen reading and could have been injured by the flying glass from the
bulb. The fuse didn't open. Has anyone ever seen or experienced something
like that before? Why would that happen? Thank's for any info and sorry for
my approximate english.

Sometimes the glas part of the bulb explosion-like separates from the
metal socket and flys off (in one pice, at least until it hits
something).

The second possibility is that the bulb imploded, that is the glass bulb
itself cracked under the force of the (partial) vacuum inside. The
fragments then move towards the centre of the bulb (in an explosion they
would move away from the centre). However, as the fragments don't just
stop at the centre, an implosion is operationally indistinguishable from
an explosion.

Both occasionally happes (often when the light is switched on or after a
brown out), without any apparent reason and unpredictably. Just one of
the risks of modern life, I guess.

 

[Richard]

Sometimes the glas part of the bulb explosion-like separates from the
metal socket and flys off (in one pice, at least until it hits
something).

The second possibility is that the bulb imploded, that is the glass bulb
itself cracked under the force of the (partial) vacuum inside. The
fragments then move towards the centre of the bulb (in an explosion they
would move away from the centre). However, as the fragments don't just
stop at the centre, an implosion is operationally indistinguishable from
an explosion.

Both occasionally happes (often when the light is switched on or after a
brown out), without any apparent reason and unpredictably. Just one of
the risks of modern life, I guess.

Halogen lamps are particularly prone to this and can be quite
dangerous. I once saw one explode on the Carson show. It started
little fires everywhere the glass shards landed including the guests
dress. Usually there was a scrim over those studio lamps for safety.
This one must have been missing. I have seen them forming huge bubbles
of quartz just prior to exploding.

Richard

 

[Steve Evans]

Sorry if it's the wrong newsgroup but I've came here before so I thought of
asking here first...
Today in our home kitchen a standard 100-watts light bulb "exploded". It
happened just like that for no apparent reason, my girlfriend was in the
kitchen reading and could have been injured by the flying glass from the
bulb. The fuse didn't open. Has anyone ever seen or experienced something
like that before? Why would that happen?

I can beat that. I was saw a sherry glass spontaneously fracture into
a myriad of shards right before my eyes, for no apparent reason at
all! I can understand the odd light bulb going 'pop' from time-to-time
since it is, after all, hot, stressed and has a limited life
expectancy. One expects a bit better from a simple drinking vessel,
though...

 

[William J. Beaty]

Today in our home kitchen a standard 100-watts light bulb "exploded".

I stumbled across the explanation under a Britannica entry for Argon.

Manufacturers put argon in light bulbs as an inert fill gas. Unfortunately
argon has a low breakdown voltage, so if the filament burns out, an arc
will leap across the broken ends. So, manufacturers put some nitrogen
in the argon to raise the breakdown voltage.

But sometimes an arc will strike across the broken filament ends.
When this occurs, the normal "yellow" light bulb color will turn
brilliant blue-white for a moment (until the filament is vaporized
by the arc, and the arc quenches out.

But sometimes the arc continues for too long. Or perhaps the
manufacturers got the gas mixture wrong. The hot arc will cause
the argon pressure in the bulb to skyrocket. The bulb will burst
with a bang.

(A similar thing occurs if you put a bulb in a microwave oven for
a couple of minutes. The hot plasma inside the bulb will vaporise
the filament parts, then cause the bulb to explode via overpressure.)

 

[Dr Engelbert Buxbaum]

Richard wrote:

Halogen lamps are particularly prone to this and can be quite
dangerous. I once saw one explode on the Carson show. It started
little fires everywhere the glass shards landed including the guests
dress. Usually there was a scrim over those studio lamps for safety.
This one must have been missing. I have seen them forming huge bubbles
of quartz just prior to exploding.

I'd guess so, their operating temperature is much higher than that of
ordinary incandescent lamps. The screen btw helps not only against
flying bits, but also screens the UV ratiation produced by the lamp
(higher temperature -> more light of shorter wavelength)

 

[tlbs101]

Richard wrote:



I'd guess so, their operating temperature is much higher than that of
ordinary incandescent lamps. The screen btw helps not only against
flying bits, but also screens the UV ratiation produced by the lamp
(higher temperature -> more light of shorter wavelength)

Back when I went to college I worked at a number of television
studios. Occasionally I would have to replace the halogen lamps in
the studio lights. They were typically rated 1000W and "ran" very
hot. The bulbs were wrapped with special handling paper. If you
accidentally touched the bulb with your bare fingers, the slight
amount of oil from your skin would be enough to cause an instant
explosion the first time the bulb was turned on (they "docked" your
pay if that happened).

I doubt that is what happened to your 100W bulb. Given that millions
of bulbs are manufactured each day? week?, statistically some will
have slight flaws that will cause this type of failure.

Tom

 

[Richard]

I stumbled across the explanation under a Britannica entry for Argon.

Manufacturers put argon in light bulbs as an inert fill gas. Unfortunately
argon has a low breakdown voltage, so if the filament burns out, an arc
will leap across the broken ends. So, manufacturers put some nitrogen
in the argon to raise the breakdown voltage.

But sometimes an arc will strike across the broken filament ends.
When this occurs, the normal "yellow" light bulb color will turn
brilliant blue-white for a moment (until the filament is vaporized
by the arc, and the arc quenches out.

But sometimes the arc continues for too long. Or perhaps the
manufacturers got the gas mixture wrong. The hot arc will cause
the argon pressure in the bulb to skyrocket. The bulb will burst
with a bang.

(A similar thing occurs if you put a bulb in a microwave oven for
a couple of minutes. The hot plasma inside the bulb will vaporise
the filament parts, then cause the bulb to explode via overpressure.)

Well that explains a lot! Sometimes when a bulb goes out you can get
it to burn again by flicking it. Sometimes the filament will fuse back
together and it will burn again.

I have seen that brilliant blue-White arc sometimes when a bulb burns
out. It can be quite brilliant and very violent.

We also used to use dichoric glass in front of quartz lamps to change
the color temperature.

Richard

Richard