[TowerTalk] Ground system design, RF vs AC

[Martin AA6E]

Keith,

I believe "fault" is the general electrical term for power going where
it shouldn't.  That's why we have protective system grounds in AC
systems.  If there is a short circuit in an appliance connecting the
hot side to the chassis, a fault current flows in the ground lead and
the user is protected.

A GFCI detects even tiny fault currents and shuts off the circuit asap.
(It detects a difference between hot & neutral current, as you
suggest.)  That's a good thing, but old-fashioned fault protection
involves blowing the upstream fuse or breaker with an overload current.
 That's one reason why your branch circuit wiring has to be matched to
your breaker - to be sure it will trip quickly if there is a short.

If you cross-connect your ham & AC power grounds, any such fault
currents will flow in your ground system too, for better or worse.

-Martin (who is not an electrician)

--- Keith Dutson <kjdutson at earthlink.net> wrote:

> You wrote:
> >The problem with connecting the AC green wire to the radio room
> ground and
> then connecting my bulkhead "SPG" to a new ground rod or even a
> perimeter
> ground connection is that my radio installation becomes part of the
> AC
> protective ground system for the house.  That is, any house fault or
> other
> current will partly be routed through my radio ground system. Is that
> what
> we want?
> 
> When you say "house fault" I assume you are referencing a ground
> fault
> circuit interrupter (GFCI) system.  Such a system interacts with the
> white
> neutral ground, not the green safety ground.  So the answer is yes,
> we do
> want the safety ground connected.
>...