Ron,
I believe there is a NEC requirement that all grounds be connected
together. I have a perimeter ground around my house with an 8 ft.
driven ground rod at every corner (total of 10), and all are connected
with a #4 bare solid wire. The wire is also connected to the utility
ground rod. This ground is then connected to the extensive grounding
system in the antenna field which grounds all towers and masts. All
feedlines into the shack are protected by 2 Polyphaser suppressors (one
at the antenna field. All wiring into the shack area (power, telco,
ethernet, and antennas) enter through a grounded copper panel and are
surge protected there. I should have little ground potential difference
in the shack area because of this 'single point grounding window'.
If I do get a lightning surge, I trust (hope) that surge will be more
gradually dissipated in the extensive ground system since it will
attempt to spread the surge out over about an acre of land (yes, I used
LOTS of wire), but I still do not operate with storms in the vicinity.
The real point relevant to the prior discussion is that *all* my grounds
are tied back to the utility ground entry point.
As a second note, I know the building inspectors (at final inspection
time) in this area do check with those little 'hardware store checkers'
to make certain that the receptacles are wired properly. It is also
common for a used home buyer to hire an inspector who will check all the
receptacles in the house for proper wiring. While that practice may not
be universal, one can do his own check on the house wiring with a $10
device from the hardware (or DIY) store.
73,
Don W3FPR
Ron D'Eau Claire wrote:
Fred wrote:
And secondly, which now makes much sense, that no
secondary ground rods are to be used! - for one's
electrical service in the home or facility.
Multiple grounds, can create shock hazards.
And as Don pointed out - a separate ground
rod, if used at all, may be useful for one's RF
antenna system, and that is all. But for ESD - the
single home and facility ground connection - is the
ONLY one to rely on for ESD safety.
------------------------
I just went through that with an electrical contractor myself. There seems
to be a lot of contradictory information.
As the contractor pointed out, there must be only one mains ground in a
building, but that does not mean there are no other grounds! The phone
company often installs a ground rod at their service entrance that is not
connected to the mains ground. The cable TV company may drive in a ground at
their service entrance to ground their cable. Add to that any iron water
pipe that runs into the earth to the water meter, etc., and there may be
several separate grounds in the home even without adding a grounded Ham
antenna!
Those grounds do present shock hazards if anything goes wrong with the mains
ground or if the hot side of the mains circuit is exposed so that someone
can touch it and any grounded conductor. That's why GFI interrupters are
important in locations where secondary grounds are often encountered such as
kitchens, laundry rooms, basements, bathrooms, outlets in out buildings such
as garages, etc.
If one grounds a Ham antenna at the at the antenna tower or mast, maybe the
shack also should have GFI protection. I don't have such a grounded system
so I haven't asked a contractor that question.
Ron AC7AC
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