[Elecraft] OT: Ground rods and concrete

[Edward R Cole]

I should preface this by saying I live on the Pacific Coast of Alaska 
(2 miles from salt water).

I worked in two-way communications for 30 years and recall all towers 
having external copper lines from the top to ground rods external to 
the concrete base. Most of the hardlines were equipped with grounding 
kits tied to that ground rod.

Also, my house has no concrete slab (4-1/2 foot high crawl space with 
concrete block foundation walls interior of the crawl space is lined 
with HD plastic vapor barrier with bare ground floor under the 
plastic).  Attached garage is on concrete slab.

My 240vac service is buried from transformer box at property edge 
with buried utilities for about 1/4 mile where utilities run on 
wooden poles.  There is a copper ground rod below my power meter box 
with what appears to be No. 10 solid copper ground wire.  Service 
wiring is aluminum.  Telephone service box is adjacent to power meter 
and ties its ground to the same ground rod.

My ham shack is the third bedroom on opposite side of the house where 
I installed a ten-foot copper ground rod.  I have a tower at end of 
house (about 40-feet from the ham radio entrance) and another tower 
45-feet from the other end of the house.  I run 120-foot 1-5/8 inch 
hardline from that tower to the ham radio entrance and ground the 
shield at both ends with a copper ground rod.  The ground rod at the 
tower is tied to ground radials (on ground surface) for my 
inverted-L.  To tie the radio ground rod to electric service ground 
rod would require about 100-foot run around edge of the house.

However, I did run 45-foot of 240vac via the crawl space to the ham 
shack with 4-conductor wire which has No. 10 copper safety wire tied 
to ground at load center and at 60A breaker box in the shack, so all 
shack grounds including the shack ground rod are tied back via that 
cable.  Main ground tie from 60A box to shack external ground rod is 
via No. 8 (includes grounding of 4.2kV PS to earth ground).

Neither tower is bonded to a ground rod, so I have no lightning 
protection, though LMR-600 line on the tower ties the top antenna 
structure to the ground where the 7-16 DIN coax connection is made 
with the 1-5/8 line.  That may offer some static drain but not lightning rated.

Fortunately the maritime climate does not produce lightning wx.  I 
have heard thunder maybe three times and seen a couple lightning 
flashes over the 25 years living in this area.  Not saying it can't 
happen but the risk seems minuscule.  BTW no lightening crash noise 
on 80m in summer (except that propagated by ionosphere from somewhere 
hundreds or thousands miles away).

73, Ed - KL7UW
   http://www.kl7uw.com
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