Ground is usually earth. You can tie ground and negative(-) together to insure that you are referenced to your surroundings. If for instance, the power supply wasn't grounded to earth, then it's possible that a potential difference between the power supply and ground could develop to the point of damaging it's circuits or at worst shock you.
in a 3 phase system the star point of the alternator is connected to earth via a large copper rod driven into the general earth,the phases are 120 degrees apart and connection between 1 phase and the star point gives 230 volts,connection between 2 phases gives 400 volts,this is based on uk wiring.the neutral point carries zero volts under normal conditions as does the neutral wire in the cable.put simply on a normal wiring system you could touch the neutral point of your wiring and not receive an electric shock.However this is not advisible unless you know what type of system you have as some systems are fed through a special type of transformer and although the wires are called LIVE and NEUTRAL THERE IS IN FACT A VOLTAGE ON EACH WIRE.
PHASE- carries current to your home and have high voltage of course
NEUTRAL-it's tha one which carries the current back from your houseto the power station.
neutral wire is harmless to touch as it does not carries any voltage coz it is connected to ground at the power station or to the earth wire
The voltage on the neutral line is near ground potential, because it is grounded at 1 or more points. It will not be at exactly ground potential, because there will be some IR drop on it.
In point of earthing and neutral
