Plasma arc failure of mains filament bulbs

Philips lamps used to have fuses built into the stem to prevent an internal arc from blowing any external fuses. The problem was that they cost a penny or two more, so none of the retailers in my area would stock them.

Before buyig a bulb, it should be possible to see through the neck whether it contains just plain wires or a pair of tubular glass fuses.

Do you buy cheapie "no-name" bulbs?

Try a Philips bulb -- at least for the US they make incandescent bulbs with "dumet" wire inside the glass rod portion.

Tungsten arc is a common failure mechanism of these bulbs. Projection and theatrical lights have much heavier filaments and so the problem is a lot worse. There's not a whole lot that can be done about it, and certainly bulb orientation won't have any effect.

Fuses? This is exactly what fuses are FOR, to remove current to shorts! Properly designed and sized triac dimmers should survive at least a few of these incidents, but cheap dimmers are probably designed to only survive the normal load current. A fuse fast enough to protect the dimmer will probably cost MORE than the dimmer, but they are available.

Jon