personal safety - preventing electric hazard
As with most electrical items and wiring schemes I've come across the most common method for preventing serious shock is a residual current breaker: -



It works by sensing the current in live and neutral and if slightly different (implying a current to earth) it trips. It does this magnetically like this: -



Principle of operation.


Electromagnet with help electronics
Current transformer secondary winding
Transformer core
Test switch


L live conductor

N neutral conductor.

All this information and more can be found here on wiki