After reading some of the posts here, I'm wondering if these protective
(1) open-neutral detector in the main panel -- to detect open neutral before
the main panel for two-phase panel and should cut off the two hots
immediately when this condition is detected.
(2) ground current monitor/alarm -- the ground wires are normally not
supposed to carry any current. So why not put an amp meter on the ground
wire in the main panel and sound an alarm if a current is detected? You
would need to separate the ground bar from the neutral bar and connect them
with an amp meter.