The 'neutral' is also connected to ground. This comes from
a LONG ago decision for safety.....with today's array of
possible ground sensors, this is at best a questionable
decision. For example, on combat ships, the 115 volt
system is UNgrounded.......nobody wants a fuse to blow
or a breaker to open if a wire touches ground during
combat. Instead, the ships have a 'Ground Fault Detector',
which indicates if the system touches ground.....that is, if
one wire touches ground. The crew they carefully isolates
(removes from the circuit) various items until the ground
fault is located, and cleared.