Greetings everyone, hope you all doing great.

I noticed that in my plant that there is two ground grids one for electrical equipment and one is for instruments, my questions are as follows:

first, why is the ground is a closed loop? for electrical it is consists of four interconnected rods !
second is, why is there distinct ground grids for E and one for I? why not one grid ? if so what would be the problem?! I know already that electrical and instruments have different ratings and instruments are low voltage.

Thank you in advance.

 

I don't know but can imagine it could be to isolate the equipment noise from the instrument readings a bit.