Exploding Incandescent Bulbs?

[JFletcher]

Just got to see this phenomenon up close and personal... 100W Sunbeam bulb grenaded its outer envelope and littered the sink, counter, and floor with broken glass, while I was showering... fortunately I wasnt shaving or brushing my teeth. Bulb was not physically hit with water or anything else, no MWBC failed neutral to cause a voltage spike. Bulb had been on maybe 3 minutes when it blew. I believe the filament lasted until the glass blew, then burned out, not the other way around. The filament is still largely intact, i.e. no big pieces missing/dangling.

Thoughts? Condensation on outer shell caused the failure when it heated up? Mfg defect? Just my lucky day?

 

[K8MHZ]

Just got to see this phenomenon up close and personal... 100W Sunbeam bulb grenaded its outer envelope and littered the sink, counter, and floor with broken glass, while I was showering... fortunately I wasnt shaving or brushing my teeth. Bulb was not physically hit with water or anything else, no MWBC failed neutral to cause a voltage spike. Bulb had been on maybe 3 minutes when it blew. I believe the filament lasted until the glass blew, then burned out, not the other way around. The filament is still largely intact, i.e. no big pieces missing/dangling.

Thoughts? Condensation on outer shell caused the failure when it heated up? Mfg defect? Just my lucky day?

My guess is a mfg. defect.

Look for the 'Made in China' quality assurance mark on the bulb.

Sunbeam is now just a name that Chinese manufacturers use. I have some Sunbeam cookware that is absolute junk. It has the Sunbeam logo and everything, along with the 'Made in China' quality assurance label.

 

[just the cowboy]

Was there still glass in the base

Was there still glass in the base

When it exploded was there still glass in the base or did the glue give out?
Condensation would have to drip on it not built up, I have seen bulbs light under water because the glass did not get hit with the cold surge that blows them up.
Was this a new bulb or used before?

My guess was it was cracked already before turning on.

 

[JFletcher]

When it exploded was there still glass in the base or did the glue give out?
Condensation would have to drip on it not built up, I have seen bulbs light under water because the glass did not get hit with the cold surge that blows them up.
Was this a new bulb or used before?

My guess was it was cracked already before turning on.

There is still glass in the base. Used bulb. Was thinking if the condensation were uneven, it would cause uneven heating/warping of the glass and subsequent shatter, tho I dunno how the condensation would be uneven- that bulb was on this morning at 6am, and again at 11am.

K8MHZ, yep, cheap bulb, believe it's a dollar store brand. Regardless, never seen one blow in this manner.

 

[mgookin]

How old was that bulb?
Did you just install it or had it run fine previously?

 

[JFletcher]

How old was that bulb?
Did you just install it or had it run fine previously?

Was installed new last month... they dont last that long anyway even when they dont self destruct.

I took a pic of what's left of the bulb; will post it as soon as it hits my email.

 

[K8MHZ]

Not an uncommon occurrence.

Google "exploding incandescent light bulb"

 

[mopowr steve]

I do work for a Fairgrounds and a few years ago durring fair we had a vendor in one of the buildings relay that a bulb near her exploded. Well, I didn't show any surprise ( not new to me) this must have upset her a bit as she looked at me like I purposely put C4 in it. I calmly said that it happens then she thought I said s..t happens and I thought she was going to fly off the handle, luckily a vendor next to her set her straight.

Usually lay people assume that they explode but in reality the sequence of events are more like
A) Bulb gets hot
B) Defect in glass or cement gives way
C) Oxygen is introduced causing filament to glow bright or rupture (this is the flash they see)
D) Glass hits the floor and shatters (giving the crash sound)
This all happens so fast it can be interpreted as an explosion.

Bulbs that are in the open can be a bit scary, I witnessed a bulb in a pendant light above a kitchen sink break and the hot filament dropped down in the sink and follow the curvature of the bowl which launched it back out and over to a little dish that contained some store receipts and catch fire.......Wow should have played the lottery that day.

Definatly makes you think about where you place them in relationship to combustable materials.

 

[JFletcher]

Here's the pic of what was left:



The filament is barely broken on the right hand side next to the holder.

 

[kwired]

When lamp is operating the gas inside is going to increase in pressure from increase in temperature.

You likely had poor quality glass and it couldn't take the pressure any longer.

The lamp filament burned open because it was hot and was also introduced to oxygen once the glass broke, as soon as the weakest link burned open current stopped flowing and the rest of the filament cooled and remained intact.

Condensation is not going to occur on a hot lamp. Condensation may occur on a cold object when there is enough moisture in air surrounding it, all depends on the dew point of that air and if temperature of that cold object is less then the dew point of surrounding air.

 

[user 100]

I agree w/the others- you had a crappy bulb. When this occurs, it's unexpected and can be startling, but just one of those things.

 

[Dennis Alwon]

Here is another possibility and one which I came across years ago. The socket was very deep and the bulb when screwed in would get scored around the base from the porcelain socket. After a short time the bulb would fall out as you show.

 

[Solanaceae]

These sunbeam bulbs are cheap Chinese crap. They are poorly sealed, and it's likely moisture remained in the lamp after craptacular quality control and sealing, the moisture reacted with the hot filament, built up pressure, and BANG! Also watch out for Chinese GE halogen bulbs, those pop too.

 

[mbrooke]

For what ever reason the glass shattered, could be a defect or scratch in the glass.

 

[don_resqcapt19]

There is a lot more filament left in that lamp than I would expect to see when the envelope fails while the lamp is energized. I would have expected a lot of it to have vaporized when the oxygen hit it.

 

[faridfareal]

When it exploded was there still glass in the base or did the glue give out?
Condensation would have to drip on it not built up, I have seen bulbs light under water because the glass did not get hit with the cold surge that blows them up.
Was this a new bulb or used before?

My guess was it was cracked already before turning on.

I was thinking the same thing

 

[kwired]

There is a lot more filament left in that lamp than I would expect to see when the envelope fails while the lamp is energized. I would have expected a lot of it to have vaporized when the oxygen hit it.

but there is a fair amount of filament supports compared to some lamps. All we need is to burn one spot open and it begins to cool off. If it has less support maybe less of it remains intact.

 

[mbrooke]

There is a lot more filament left in that lamp than I would expect to see when the envelope fails while the lamp is energized. I would have expected a lot of it to have vaporized when the oxygen hit it.

Keep in mind a lot of these bulbs (with 5 supports and sold after 2014) are rough service which usually also comes with a very long life expectancy (2000hr with 130 volts bumping it like 5,000 or more). The cooler burning filament will burn up slower when exposed to oxygen, and as mentioned the weakest part will go first. If one section is already much weaker due to say a defect, it will burn open well before the rest of the filament looks even oxygen exposed.

 

[Electric-Light]

General purpose lamps are filled at a partial atmospheric pressure. An extremely tiny crack can admit air into the bulb over and take weeks to fill up the outer bulb to atmospheric pressure. When it's rapidly heated up, it builds up pressure quicker than it can escape and the combination of the positive pressure, thermal stress and weakness due to fracture formation can pop the bulb.

Rupture is more common with a double walled lamp, because the halogen lamp inside the outer bulb is not dependent on the outer bulb. This is simply because it's more likely to self extinguish from air oxidizing the filament and breaking the current.