In article ,
Tim.. wrote:
Yes, why do some dimmers have to be derated for mains halogen lights?? I
can appreciate there is more of a surge when firing up the halogens as
opposed to normal say 60w light bulbs, but the running load is the same.

Pretty well all semiconductors are rated for their *peak* current handling
capacity. Exceed that for a fraction of a nanosecond and they blow - which
is why a wire fuse can't protect them.

Dimmers are built right down to a price, so the triac they use is rated
at the minimum possible.

If and when mains halogens become the norm, I'd guess we'll see dimmers
commonly rated for them. But then you'll be able to over-rate them for GLS
types. ;-)

--
*Not all men are annoying. Some are dead.

Dave Plowman London SW 12
RIP Acorn