On Tue, 13 Oct 2009 19:51:24 -0700, Don Kelly wrote:
Other
hazards such as arcing at switches or poor contacts, worse with DC, were
ignored.

I recall the breakers at one site I was working at fed compressed air
through the breaker upon opening, just to extinguish any arc that may have
formed (that was a 400V DC setup) - I think that's typical on higher power
DC stuff. The breakers were about the size of a lunchbox.

cheers

Jules