"Owen Duffy" wrote in message
...
Roy Lewallen wrote in
:

Rick (W-A-one-R-K-T) wrote:
On Wed, 11 Jul 2007 11:35:11 -0700, Roy Lewallen wrote:


And there's a third reason and set of requirements for grounding
which is different from both of those -- AC safety ground. Its
requirements are dictated by the NEC and local electrical codes, and
it shouldn't be confused with either of the other two.

Is there such a thing as a ground that is good for both AC safety
ground and lightning protection ... or, both of those plus RF ground?

Sure. One way to do it is to make a proper AC safety ground, a good
lightning ground, and an effective RF ground, then bond them all
together (provided it's permitted by code).

Roy,

Isn't equipotential bonding part of making three independent earth
systems work compatibly with each other, to be a single system that is
effective for each of the purposes?

Owen

Roy Lewallen, W7EL


Owen

Equipotential bonding is the process whereby all exposed conductive parts
are connected together so that they are all at the same (usually earth)
potential. Cross connecting three independent earthing systems could well be
used to ensure that a system as a whole was properly grounded for power,
lightning and RF. However, you have to bear in mind that for some power
purposes, a high ohmic value is required in the earth circuit to prevent
lethal current flowing in event of a fault. Under these circumstances it
would be wrong to cross connect all the earths together. It is important to
study the design criteria for the power circuits and protection devices
before making any changes to an existing installation.

Mike G0ULI