what's need for earth wire ?

in a single phase ac power
if there was no ground stick at the power generating station .
then there would be no reason for a person to get an electric shock.
no need for ground(earth)wires.
only live and neutral wires for domestic ac supply.
what is the need for grounding in the first place?

This is not an Arduino question and the wrong answer has life-threatening consequences.

For a definitive answer you need to consult a qualified electrician or your electric utility.

...R

Robin2:
This is not an Arduino question

reason why it has been posted in Bar Sport

SumitAich:
reason why it has been posted in Bar Sport

SumitAich:
non c’è spazio per la vostra merda in un forum microcontrollore

So it’s all relative. What is good point, and what is worthless rubbish.
The judgment is always up to you.

What happens in you scenario if the distribution grid gets hit by lightning ?

Consider potentials.

SumitAich:
reason why it has been posted in Bar Sport

I meant more than that - it is a safety-related question that goes far beyond the competence of anything to do with Arduinos and I would not rely on any advice on the subject from anyone other than an electrician who is qualified to work where you live and who shows you his credentials.

The wrong advice, or the wrong application of the correct advice could result in death or serious injury.

...R

I would suggest that you go here and ask your question.

The only correct reason is "the code requires it"! Even for home use generators.

Paul

SumitAich:
in a single phase ac power
if there was no ground stick at the power generating station .
then there would be no reason for a person to get an electric shock.

So you have a current carrying wire with rapidly changing significant voltage... and somehow a grounded person won't be able to get a shock from it?

Potentially Not, unless ground changed to match which in general does not happen.

only live and neutral wires for domestic ac supply.

That's not how it works. The wires are a circuit, the entire circuit carries charge, not one has and the other hasn't. You seem to have missed a physics lesson or ten or maybe the whole course?

Boardburner2:
What happens in you scenario if the distribution grid gets hit by lightning ?

Consider potentials.

Har Har Har very funny..... good last line...

But you would think there would be some resistance to Earthed system, causing a current change in electrical regulations.

The OP suggestion is what happens at building site (with some variations) where an isolating transformer is mandatory for power tools.

With a system as vast as the Grid there would be considerable coupling to ground through capacitance and other leakage effects.

This allows current to flow from both L and N to ground.

Plus SWER systems, Single Wire Earth Return.

TomGeorge:
Plus SWER systems, Single Wire Earth Return.

Downside of that is the cost of the extra copper.

Oops i was thinking of TNS.

For domestic use a very large earth (mat) would be required for SWER.
This is not generally convenient.
I have seen it used for farm supplies however.

See how long you can run a PC using a cheater plug. I had a buddy who regularly replaced boards and other parts until one day I tracked down where he plugged the power strip in. I made him run a ground wire from the fuse box and bingo, the regular runs to the shop ended.

GoForSmoke:
See how long you can run a PC using a cheater plug. I had a buddy who regularly replaced boards and other parts until one day I tracked down where he plugged the power strip in. I made him run a ground wire from the fuse box and bingo, the regular runs to the shop ended.

Cheater plugs (I had to Google them) are NOT ALLOWED in the UK. Everything here has either to be earthed [grounded] or double insulated. We even have to earth all our metal water and gas pipes.
The symbol on double insulated equipment is two concentric squares.