Neutral Transformer

A low impedance path should be used for gronding.

If soil was used, then it must be because the design engineer considered the soil impedance was low enough for that particular application, and there are no local regulations that show otherwise.

If transfo body earthed on HV side, most HV fault current will return direct towards HV source, minimising current & step potentials on LV side.

If the LV earth were bonded to HV earth, then all gear on LV side would be hard-connected to raised voltage due to HV fault; since all this LV gear is usually bonded to LV neutral by earth return conductors.

Distribution cabinets, lamp-posts etc would be raised in voltage. There would be increased risk of dangerous potentials to metal fences, pipes etc which may be quite well connected to their local earth potential hundreds of metres from transfo, causing step potentials which may injure animals (which have their feet further apart than people & never wear boots), if not people.

Probably as a high voltage spike deterrent to sensitive expensive equipment...Earthing or grounding schemes are always used as a protective measure, what's allowed is dependent on what needs to be protected....It's not always just humans that need to be protected, computer and software control systems can get very expensive....Different regions have different requirements due to different environments....There is usually an Authority that has jurisdiction over the rules governing how things are done in any situation and location...Having everything done to a certain standard is a basic safety measure adopted by nearly all AHJ entities...

It is not true always. Some codes do allow connecting the neutral to body and connection from earth pit only to transformer body.

Most important is providing safe and sure way of passing fault currents to earth pit with shortest connections / least resistance. The requirement of redundant earth connections for body as well as for neutral etc. are also steps to achieve the same end.

Dear Sir

The body earthing and neutral earthing are separate . Body earthing is for personnel safety. It is used basically to drain off leakage currents/ charges to earth.

Neutral earthing is termed as system earthing. It is grounded to have the neutral voltage fixed to earth potential or zero potential. It is essential to keep the neutral point stable in the event of unbalanced loads.

Neutral is a return path in the AC circuit

Neutral earthing also helps in effective operation of the protection system.

Body earthing can be thru direct driven electrodes or connection to earth grid but Neutral earthing is thru pipe electrode thru treated earth pits.

Therefore, due to difference in purpose/application , the body earth and neutral earth are never mixed. If both are mixed then the earth conductor, which is not supposed to carry any currents normally ,may have some charges across and may become hazardous.

Regds

<...It is used basically to drain off leakage currents/ charges to earth...>...and to operate the circuit protective device(s) in the event of a fault.

Neutral earthing is to provide a voltage reference to earth for the phase conductors.

GA