"Jack Painter" wrote in message
news:zHhae.4351$lz1.2472@lakeread01...

"gb" wrote
in message ...
"Dave Platt" wrote in message
...
In article ,
Rob Collis wrote:

Hi Joe,
IMHO it is best to isolate the ground used in the shack from the
household
ground. This should reduce noise from any mains supplied appliances.
You
could use a third rod for the antenna no problem.

In the United States, most localities incorporate the National
Electric Code into their own local building codes. It is my
understanding that the NEC requires that each building structure have
precisely one "ground system", and that this requires that all ground
rods be reliably "bonded" together (typically via 6-gauge-or-heavier
wire).

The ground-system bonding is required in order to reduce the degree to
which ground-voltage differentials can occur in the case of an
electrical fault or nearby lighting strike. The bonding reduces the
current that can flow through appliances that are connected to two or
more independent "ground" systems (e.g. a building's main electrical
ground, and a separate ground stake near an antenna).

Putting in a second ground rod near the hamshack can be a good idea,
as it reduces the length of the ground wire from rig to ground rod and
can improve the quality of the RF ground (depends a lot on wire length
and frequency). However, in order to comply with the NEC, this ground
rod must be bonded to the main building ground.

I don't know what the rules are in other countries.

--
Dave Platt, AE6EO

Dave is correct about NEC requires, HOWEVER please check with you local
municipal (or country/parish) building department (or code enforcement) -
there are variations that are more restrictive than NEC in SOME U.S.
localities.

That said, IF you are going to have a tower or large antenna array - RF
grounding needs to be addressed separately from electrical service
grounding. This area also has different requirements in SOME areas (for
example - parts of Florida have the highest lightning hits per year).
Glen
Zook, K9STH has given talks and presentations on this subject - this
information can be found he
http://home.comcast.net/~k9sth/

w9gb

Please, PLEASE, disregard every bit of that RUBBISH about "dissipation"
(prevention) of lightning strikes in K9STH's website. There is not one
single piece of scientific evidence to any of that bullcrap. The theories
of
Charge-transfer-systems (CTS), Early Steamer Emissions (ESE) or ANY kind
of
lightning prevention are total malarkey. The cost of gathering
international
review and wide publication of DIScrediting these phony's is incredible,
but
the IEEE has done so over and over again.

There was good advice in this thread (and one bad one, advising isolation
of
house and radio grounds), until "gb" dragged that old nuttiness about
dissipators out of the closet.

Best regards,

Jack Painter
Virginia Beach, Virginia


" but the IEEE has done so over and over again".
-------
As a member of IEEE, ... my esteemed association strongly supported BPL ..
which I consider a rubbish, politically motivated usage of network
technology.
Their creditability is suspect moving forward.

As for NEC -- Chicago area standards which are stricter - and will not
permit some lower requirements under the NEC.

As for what is important at the end of the day - I have found that unless
the insurer for the property and equipment
agrees with the installation (and design) -- they won't pay for damage - no
matter what was followed !

Although single point grounding should be used (as Jack points out) - over
the past 30 years I have seen so many "in the field" violations of that
principal (telephone, power, cable, broadcasting companies) -- and I am not
the policeman for these installations or their engineering arguments - why
they were installed that way.