Joe,
I didn't just suggest that the grounds be bonded (connected
electrically), the NEC requires it. Placing a ground near your
antenna base and near your shack will provide a path from your
equipment to the ground that is less than a quarter-wave at 30 mHz.
This will help keep the ground wire from radiating. If you do not
comply with the NEC sec. 250 requirement, your insurance carrier has a
case for not paying your claim. Multiple ground rods lower the
impedence to earth in case of a lightning strike. Lightning is
largely RF and will "prefer" a low impedence to earth. Bond the
grounds together with #6 or larger wire. Don't take my word for it,
ask your insurace company. I am a former Telco employee and grounding
there is a religion, and not a minor one. See the BSPs ("Bell System
Practices", now "Best Suggested Practices") and the web site of the
Erico corporation. A. J. Surtees is one of THE authorities on
grounding.
Russ
On Sat, 23 Apr 2005 02:04:29 GMT, "Joe" wrote:
If I understand correctly the just of these replies, -- I would be better
off if I installed a so-called "stand-alone" ground rod that was several
feet a way from the ground rod that my home was on and use this
"stand-alone" ground rod solely for my shack equipment, and then driving
another ground rod by my Butternut vertical and connecting it to the antenna
ground rod. Am I correct in this? What is confusing to me is what one of
the replies suggested that the rods be bonded or connected together. If that
is a correct thing to do I don't see what the difference would be to using a
single ground rod. After-all a ground rod is a ground rod.
Thanks again for all your help.
73's
" 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