What causes incandescent light bulbs to fail in a spectacular manner? Mine sometimes produce a loud bang when they expire, and I was recently freaked out when I turned on a wall switch and it produced a bright blue flash from inside the wall, at the same time that the connected light bulb failed.
While I’ve never seen (or heard) a lightbulb go bang, I’ve often seen them fail with a flash. As the incandescent element breaks, there is a brief electric arc between the ends of the severed element. I suppose that the arc could cause a sound, after all it’s miniature lightning with it’s attendent miniature thunder.
The blue flash you saw coming from inside the wall would be an arc drawn between the switch contacts as they closed. That’s not too unusual, but if you notice it a lot and it’s fairly bright, you should consider replacing the switch. Excessive arcing would indicate that your switch contacts are getting pitted and may cause a high resistance connection that could potentially lead to a fire.
If you saw a blue flash from inside the switch box you should call and electricial. Something is amiss. I doubt that it is the switch contacts since the switches are enclosed in a plastic housing.
The only time I have seen a lightbulb actually explode and throw glass around was when I accidently spill a couple of drops of water on the envelopt. In that case they go out with a loud pop.
Great balls of fire. Make this call an electrician.
I have no excuse.
I did some additional research and it appears that what I’m seeing is a “burnout arc”, which produces a near short-circuit when the inert gas (nitrogen and/or argon) inside the bulb ionizes during a filament break. The bulb is supposed to have a fusible wire element to limit the current and prevent damage to other hardware. What’s the short-circuit current on a typical home AC circuit?
Only the inside of a lightbulb is almost a complete vacuum, so this is an invalid point.
Home lighting circuits are typically protected against steady-state currents of more than 15 A. There will be a transient current spike greater than that for a few milliseconds before the the breaker can activate. What that might be is anybody’s guess.
The breaker mechanism is designed to separate its contacts very rapidly in order to minimize arcing.
Not true. Many are filled with inert gases like argon.