Should a shorted to ground heat pump compressor cause the breaker to trip?
Mine doesn't. It seems to me the breaker should trip or you should get lit up when you touch the outside unit.
Thanks,
Jr

Usually it does but you need to make sure power is present before the compressor is activated.

An electrical ground is 0 ohms resistance, a lot less than you . That's why if you grab a 120 VAC line on a carpeted or wooden floor you probably won't get shocked. Don't do it outside or on a concrete floor, particularly in bare feet!

If the disconnect has fuses, they will likely blow before a breaker trips.