"Andrew Gabriel" wrote in message ...

I dissected a larger CB some years ago (I think it was 200A, and
I don't know what it came out of). That had an air chamber and
plunger to extinguish the arc with an air blast. Initially I
thought it was a damper, but it didn't damp the trip mechanism.
Then I realised it generated a blast of air through the contacts
and through a mica honeycomb, and the mica did look like it might
have had an arc blown into it -- some vapourised metal in it.

The designers must have a lot of fun testing things like that during
development...

--
Andy