JeffB wrote:
[...]
3) Do breakers 'wear out' or degrade over time? One reason I want a
240V circuit
is I'm experiencing nuisance tripping when running my table saw under
load. Is
it possible that the breaker is just tripping prematurely?

Is your table saw ok with running at 240V? Not being a motor expert, I
would assume that it would need to be wired for a particular voltage.

How about removing the ill-conceived 240V circuit, replacing the unused
15A breaker with a 20, and wiring a new 12-gauge circuit dedicated to
the table saw?

You could make the new breaker a pair of half-height 20's so you'd have
room for a new circuit in the future.

Chip C