Re: ground question here...

["Metlicka Marc" <mystuffs-at-orwell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

yes at 240v you don't have to be concerned with a ground/neutral for it
to operate. but as sundog wished to split the 240v into two 110v
circuits, then the neutral has to go back to the main distribution
panel. but as i said the sub has to have it's own ground rod provided.
your setup is a very sound way to prevent just the rf kick into your
mains, but just as a reminder, if the breaker that your coil is wired on
is low on your box, then any kick you might get into the hots will be
seen by every circuit above your breaker. the coil breaker should be the
first breaker on the rail, then any rf will travel to the pole without
any circuits seeing it.
marc