OT: What makes light bulbs pop

[mobiledynamics]

So I'm sitting here, just catching up on work......no vibrations/kids stomping upstairs, and I catch the flick/hear the pop as one of high hats PAR20 bulbs go bad.

OT, but what causes light bulbs to go bad.

This is on a Lutron Dimmer with 2 High Hats on them.
Interestingly enough, JUST yesterday, I replaced another bulb on a different switch and I was saying to myself....watch. With my luck, when I put the box of bulbs away, another one will go bad. And interesting enough, it did

 

[MikeF2316]

So I'm sitting here, just catching up on work......no vibrations/kids stomping upstairs, and I catch the flick/hear the pop as one of high hats PAR20 bulbs go bad.

OT, but what causes light bulbs to go bad.

This is on a Lutron Dimmer with 2 High Hats on them.
Interestingly enough, JUST yesterday, I replaced another bulb on a different switch and I was saying to myself....watch. With my luck, when I put the box of bulbs away, another one will go bad. And interesting enough, it did

Generally the metal in the filament actually slowly evaporates. As the filament becomes thinner, it gets hotter and the process speeds up. Eventually one spot gets hot enough to melt, then that's the sound/flash you hear and see.

Lights with a halogen gas and quartz glass get around this problem somewhat because the metal in the filament stays vapourized and redeposits on the filament. So they can run hotter and brighter, but eventually there's enough moved around that the same failure happens.

 

[Zeke]

That's ^^^^ a good explanation. Thanks.

 

[myredracer]

Halogen lamps don't like to be run dimmed for long periods and will result in blackening and early failure because dimming (below around 70-80%) interrupts the internal regenerative cycle. You can periodically turn them up to full brilliance for a while to "restore" them or turn them up to 100% for a minute before switching off each time. Or use a lower wattage lamp and run it at 100% all the time.

We have an alcove on either side or our fireplace & TV with a couple of low wattage halogen PAR lamps in each and have a dimmer for them. I have them turned down most of the time, esp. when watching TV, and they have been fine for around 8 years. I periodically turn them up to full brilliance for a while. I'd hate not to have a dimmer for these.

 

[Strouty]

Thanks for the explanation, never really pondered it before.

 

[mobiledynamics]

Mike -

Thanks for the explanation.

OT, but do miss the Halogens in the Kitchen. We switched over to some High CRI LED mainly due to the heat in the summer (entertainly frequently, and kitchen get's hot). LED's were $$ High CRI. It's a bit whiter than I would like, even though the stated color was 3K for them.

 

[Richard Cranium]

thanks for the info

 

[LS6 Tommy]

Incandescent bulbs almost always go out when they're turned on as the filament is basically a dead short for a millisecond or so until it heats up.

Tommy

 

[Bigbandguy]

I had a friend who inserted a power supply diode in series with the light over his shop door because it was a pain in the *** to change. He left it on 24/7 last I heard it was still working seven or eight years later.. anyone here done anything like that .. I do not know what diode he used but he sure got good results.

 

[NUTTSGT]

One other thing to think about is that a light bulb or a lamp is made using a vacuum. Once it loses that, it will go out.

 

[LS6 Tommy]

I had a friend who inserted a power supply diode in series with the light over his shop door because it was a pain in the *** to change. He left it on 24/7 last I heard it was still working seven or eight years later.. anyone here done anything like that .. I do not know what diode he used but he sure got good results.

I don't understand what that would change. Incandescent bulbs don't care if they see AC or DC current...

Tommy

 

[myredracer]

I don't understand what that would change. Incandescent bulbs don't care if they see AC or DC current...

Tommy

Back in the 70s/80s when incandescent lamps were still king and we didn't have CFLs and LEDs, it was common to install "lamp life extending" diodes in light fixtures that saw a lot of on time like exit signs and exterior light fixtures over exit doors. It's not anything to do with AC versus DC, it's the reduced voltage the filament gets. I used to spec. them all the time on projects.

I didn't know that these diodes are still available like here:

http://powerdisc.com/about-powerdisc/

 

[wyliesdiesels]

Interesting. Never heard of those before.

 

[DC73]

It's not anything to do with AC versus DC, it's the reduced voltage the filament gets.

Yep. The problem is that for years light bulbs (especially residential grade) were manufactured assuming a 110/115 voltage system and were rated at only 120 volts. Most power systems today provide more than 120 volts. I used to live near a power company substation and routinely had 127 volts in my house. Incandescent light bulbs didn't last long until I discovered 130 volt rated commercial bulbs. Today's CFL and LED bulbs can better handle the extra voltage than incandescent bulbs, especially if you buy good quality name brand bulbs.

Most power companies try to maintain voltage to the customer in the range of 114 - 126 (+/- 5%) but the terms and conditions of service frequently state that during times of abnormal system conditions, the acceptable range changes to 108 - 132 (+/- 10%). The advantage to maintaining system voltages in the higher end of the range is that there is less current flowing for a given wattage.

DC

 

[Brian_WK]

Incadecent Light bulbs that are frequently turned on and off last shorter then leaving the light on all the time due to the high amp draw on start due to the cold tungsten. Also the expansion and contraction created when the tungsten is heated from room temp to 3400 C in a split second.

Brian

 

[Stevie-Ray]

I used to live near a power company substation and routinely had 127 volts in my house.

That's what mine registers in my present house.

 

[MikeF2316]

One other thing to think about is that a light bulb or a lamp is made using a vacuum. Once it loses that, it will go out.

Originally, light bulbs were made with a vacuum inside. When metal filaments came predominant, it was discovered an inert gas (usually argon) slowed the evaporation process. And in halogen bulbs, the halogen gas is necessary for the regeneration process.

However, in all cases, once oxygen from the air gets in, filament burn out in short order.

 

[gungatim]

I had a friend who inserted a power supply diode in series with the light over his shop door because it was a pain in the *** to change. He left it on 24/7 last I heard it was still working seven or eight years later.. anyone here done anything like that .. I do not know what diode he used but he sure got good results.

From what I understand, a bulb running on AC is more efficient and will last longer than running on DC. adding the Diode is doing the opposite of what your friend thinks...has to do with inconsistent re-depositing of the vaporized filament...

 

[LS6 Tommy]

Back in the 70s/80s when incandescent lamps were still king and we didn't have CFLs and LEDs, it was common to install "lamp life extending" diodes in light fixtures that saw a lot of on time like exit signs and exterior light fixtures over exit doors. It's not anything to do with AC versus DC, it's the reduced voltage the filament gets. I used to spec. them all the time on projects.

I didn't know that these diodes are still available like here:

http://powerdisc.com/about-powerdisc/

That doesn't just reduce the voltage, it rectifies it, too. That makes sense, I thought the guy was just using a single diode of some sort, not a rectifier...

 

[woodzy]

We had a fixture in our shop that was very hard to reach - we used it as a night light and put a 220V bulb in a 110 Volt socket. It ran 24/7 and I think it lasted 20+ years... It was 1/2 the brightness but we wanted it just for a nightlight.

 

[stevep500]

I wonder if the diode idea was a single diode in series with the bulb to allow only one half of the full AC cycle to go through the bulb. It doesn't make much sense because it would cut the power by half. This should extend the life considerably but with considerable reduced light output.

On another angle, the pop could be caused by a weasel...

as in "pop goes the weasel."

 

[nadogail]

The ner Tamid ( perpetual light) above the Arc in my temple has a diode in series with the light, it has been lit for several years. I believe this long life is because the filament "cools" during the half cycle the diode is blocking the current.