[Boatanchors] Grounding (may be a bit long)

[Dave Maples]

All: I don't have as extensive a ground rod field, but it's bonded to the
service entrance, the telco entrance, and the CATV entrance.  It's 4 rods
connected with #6 AWG solid wire going a quarter of the way around the house
to where my shack lives.  Mechanical connections on the rods (I'm too cheap
for cadwelding).  I just cleaned all the connections and redid them,
applying NOALOX as I did so.

For me, basic grounding is cheap insurance.  It was half a day of work the
first time for me, and I know now how to make it go faster...rent the
dog-fence trencher that cuts a slit 4" deep in the ground and you can bury
all kinds of ground wire pretty quickly, not to mention all those radials
you don't want to hit with the aerator any more!

The commercial and Fed worlds do more.  I currently work as a cell site
equipment standards engineer for Nextel (now Sprint).  Before that I was
doing the same thing as a Fed contractor for NASA.  In both cases we used
Motorola R-56 practice on grounding for the most part.  Other folks'
standards seem to be about the same.  They generally call for stuff like the
following:

a. Ground ring around the tower or antenna support structure, with rods
bonded to the ring and to the tower legs.

b. Ground ring around the shelter or cabinet bonded to the tower ground
ring, with rods at corners and every so often in the middle.

c. Ground ring around shelter bonded to AC and to telco grounds.

d. Coax cables bonded to tower with grounding kits at top, at bottom where
they leave the tower, and bonded to the shelter ground ring where they get
ready to enter the shelter.

e. Equipment cabinets bonded to the shelter ground ring through an internal
ground bar.

f. Surge arrestors on every wire that enters the shelter.

It really works, too.  At the NASA facility we sustained multiple direct
lightning strikes on the UHF trunked system antennas (that blew holes in the
antennas) but never sustained damage to equipment.  Conversely, in the same
facility but before the grounding was done properly (the previous engineer
didn't bond the tower grounds to the building ground) a lightning incident
caused several thousand dollars of equipment damage(including gaussing every
color monitor in the video area, which was adjacent to the radio room).

How much you do depends on the probability of a strike and how much is at
risk.  There's also the liability factor if you are building for someone
else, but I'm no attorney so I won't try to comment on that.

Maybe this will help.

Dave Maples