Only in some homes, I a lot of cases, there is loads like lights, stove and geyser not connected after the earth leakage, in that case you would need to use the Main Switch / Isolator to kill the power.
It is done in a three phase installation with only a three phase breaker. I personally would prefer a 4 pole breaker and breaking the neutral as well, but its only a personal choice.
As long as the Neutral is bonded to earth at the transformer/mini-sub it will be safe. There will be no potential difference between live and neutral and you would not be able to get shocked by touching the neutral.
Edit: Unless you disconnect a neutral from the neutral bar, and then hold that neutral wire in one hand and the neutral bar with the other while the load is switched on..