"JANA" writes:

All incandescent light bulbs use a tungsten filament. When the filament
fails, this is because it eventually melted away to be an opened circuit.
Over the lifetime of a light bulb, as the filament is heated to near white
hot temperatures to generate light, it starts to slowly break down.

When the filament in a lamp burns out, it sometimes has a bit of a meltdown.
Sometimes pieces of it can short out the metal support contacts feeding
itself. If there is a short, it can cause a fuse to blow, or a circuit
breaker to go to the open mode.

Geez, this again???

While the scenario of the bits of the filament shorting is possible with
some lamps (usually with long thin filaments, though unlikely with the
short filaments of halogen lamps), the more likely cause is the arc
resulting when the filament opens. This results in the arc moving
towards the filament supports, with a lower resistance than the filament
had originally, leading to a high current.

See: http://members.misty.com/don/bulb1.html#wbs

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