The whole grounding thing has me a little confused, here's what I
think I understand as correct.......(I hope I'm using the correct name
for all of these things.)

The grounding conductor from the main panel to grounding electrode
must be continuous, no splices.
The grounding conductor & neutral are only connected at main
panel.....neutral & ground busses remain isolated at sub panels.

An underground metal water pipe (20') is the preferred grounding
electrode, if one is available. Grounding rods would be supplemental
(?) & merely recommended in this case (?) as a backup in case the
water line is replaced?

So ideally the grounding conductor would run from the main panel to
each of the grounding electrodes (water pipe & ground rods) without
being cut? Like doubled over at the rods on the way to the water
service?

How about the sub panels?

One of my sub panels is located half way between the main panel & the
front of the house where the 1" copper water pipe enters the house.

My old grounding system was a # 4 or # 6 connected to the galvanized
piping at approximate midpoint of the house.....about 25' from water
service entrance. But now all the galv is gone.

Prior to PEX / copper repipe, I drove a couple temporary ground rods
at the main panel.

My plan is to finish the grounding system properly by running a # 4
from main panel to water service entrance,

The #4 run from main panel to water service entrance runs right passed
one of my sub panels.

My idea was to split nut a grounding conductor from the sub panel onto
the "main grounding conductor" along its run from main panel. Of
course, not cutting the #4 "main grounding conductor" at this
connection, just merely split nutting onto it.

This would bond the sub panel ground back to the main panel without
having to run an separate conductor back to the main panel from the
sub.


Does this make sense & is it correct (ok) to do what I am planning?
Or do I have to do something else?

The whole grounding thing has got the be the most complicated &
difficult part of electrical wiring........makes my head hurt.

cheers
Bob