helogen light dimmer

[bernardgreen]

]Well, I sort-of mentioned it:

Sorry... I didn't read the thread carefully.

Generally these have an in-built thermal link and, should the lamp filament short out, the thermal fuse stops the inrush of current which can damage a dimmer.

If only it was generally so,

And in the few that do have a fuse the reaction time of that fuse is too slow and the dimmer is blown before the fuse has opened. The surge of current is due to a plasma arc in the lamp in the vapourised metal from the filament. This pulse has a very rapid rise and that is what takes out the dimmer as any protection circuit is too slow to operate. ( in more expensive dimmers there is (often) better protection )