Some footnotes for all:
Very few dimmers use active
current limiting. Back in the 70s/80s, some
TTI dimmers actually had a
current monitor loop that would inhibit
SCR firing if too much
voltage drop occurred across the
choke. Shame they were so ugly looking
About the only thing that limits
current in most
dimmer circuits these days is the
drop across the
wire between the
dimmer and the short. This is why some survive and some don't. The closer the short, and the heavier the
wire, the greater the chance the
Triac /
SSR /
SCR /
IGBT goes bye-bye!
If you have a direct short and use the proper
gauge wiring then the device will often fail before the
breaker kicks or the
fuse blows. Some dimmers use "silver sand" or "rectifier" fuses that are designed to fail real fast. They are much larger then the expected load (20 amps for 1k
dimmer) and are used in combination with standard fusses or
circuit breakers which are rated at the normal
current output. As to if this works, well, the opinions are mixed.
Breakers and fuses are good at stopping general overloads before damage is done. On direct shorts, they are good at preventing a fire, not as good at protecting the switching device. Lamp flashovers can fit in either
category, but usually a good
dimmer will survive.
This is one case where an ounce of prevention is worth a pound of cure. Always inspect your cables, connectors, and lights for possible shorts.