Commercial-grade switch? I think not. This looks like a "T-rated" (tungsten) AC/DC switch, not manufactured since at least the '70s.
This is totally a hack job, of course, but at the time it was done, it may not have been illegal to use green as an ungrounded conductor. This rule was phased in during the '60s, I think. I have seen at least a handfull of pre-1970 (very professional) installations where green-insulated conductors were used as ungrounded system conductors.
Everyone, be on the lookout for this, especially since most of us are now too young to remember when such installations were new.
