First Thing First.

Earthing is the first thing to install in electrical field.  Earthing is
essential for human safety, but not really understood by the protected.  
Often I hear "That is only an earth".  Well, without earthing, you motor
will run. But without earthing your are potentially in danger. So, I  alway
say "Earth comes first".

I made a lot of sketches relating safety earth.  In the sketches, I used a
word "grounding". American people use "grounding" instead of
"earthing", I have been working with NEC long time.   So, let me use
grounding and earthing interchangeably.  I would like to add more on
safety earth based on IEE or IEC when I have time to do so.

See the sketch first.  Each figure need some explanation or story.  I will
add some narratives  later.
Safety Earhting
Earth for Safety