I'm going to relate this story, because, it underscores
the need for a 'static-electricity drain path' to earth; the
NEC may be seeking in their usual round-about way
to provide this, albeit without outright stating so (in the
vein of 'Rules without explaining the Rationale').
One day in a time in the not-so-distant-past a friend of
mine noticed a 'ticking' sound coming from the back
of his TV set.
It was connected to an outside TV antenna whose mast
was not connected via -at least- a static drain wire (if not
'ground' as the NEC-world would call it.)
There were 'storm clouds' in the area; his set was not struck
by lightning (this ticking had gone on for several minutes, it
wasn't just a one-time event). The set never operated quite
the same after that episode ...
Let me relate another story, this one occurring IN the distant
past.
A wee young lad of no more than sixteen consructs
an off-center fed widom, feeding it with 300 Ohm twin
lead. This antennna was up about 25', tied to a tree on
one end and a guyed mast out in a field on the other;
ceramic insulators were used on both ends.
One day, this wee lad receives a shock handling the
stripped wires at the end of the twinlead, the end
opposite the antenna. To his astonishment, the young
lad sees that he can 'draw' small arcs from the stripped
twinlead wires on nearby the water pipes (as this was
in the basement they were easily accessable as they
were running overhead)
The lad will have nothing further to do with this phenom
at this juncture (fearing a lightning hit due to 'storm
clouds' in the area) and throws the twinlead feed line
out the basement window!
Moral of the story: rain-producing cumulus (at least)
can produce high levels of static electricity in an area
necessitating the use of 'static electricity drain path'
(ground) wires to reduce (keep low) the amount of
built-up electron charge on conducting structures
for the purposes of personnel and eqipment protection.
In later years this youth, now somewhat grown up,
purchases a used JCI rotary-vane, E-field-chopping
electrometer off an internet-based open-market
bidding-house (known as eBay) and verifies the
prescence of high static-eletricity E-fields in the
vicinity of rain-producing meteorological phenomona.
JimP // WB5WPA //
----- Original Message -----
From: "rick darwicki" <n6pe@yahoo.com>
To: <rfi@contesting.com>
Sent: Saturday, December 20, 2008 2:12 PM
Subject: [RFI] DirecTV to ground or not to ground
My DTV antenna cable has an external ground wire that is broken off about 8
feet from the dish and not grounded to the converter box.
Question, for TVI (not worried about lightning around here) should I fix it
and ground the antenna mount to the box?
Thanks,
.·:*´¨`*.·: RICK, N6PE .·:*´¨`*:·.
_________________________________
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|