On Fri,9/12/2014 2:26 PM, N3AE wrote:
My main concern is that electric feeder to the garage. The feeder enters the house
basement on the "north" side and runs to the main service panel along the
unfinished basement ceiling. Don't want lightning currents to prefer that route. The
second concern is routing the coax conduit near the #4 bonding wire between the tower and
house service panel. Possible inductive coupling during a lightning event?
Hi Shawn,
There's a point of clarification needed here. Do you have one service,
or two? That is, does the from the power company go first to the house
and then to the garage (or vice versa), or do you have two feeds from
the power company, one to each building? From your description, it
sounds like you have the first option. Right?
Here's the concern. In any SYSTEM, they must be one, AND ONLY ONE, bond
between Neutral and the Green wire, and that bond must be where the
system is established (usually where power enters the building). Breaker
panels come with a bond between neutral and the frame (where the green
wires must be connected), so if there is more than one panel in a
system, that bond must be removed on sub-panels.
There is another way to do it, and that's what I'm doing with a similar
feed. I am treating my two buildings as separate (they're about 30 ft
apart). I have a single service, which comes to the house, then is fed
to the garage/apartment that houses my shack. There is NO ground
connection between the house and the shack -- the feed from the service
is two hots and a neutral only. In the garage/shack, this allows me to
bond neutral at the entry panel. Note also that there are no other
cables carrying "ground" between the two buildings.
My tower is about 225 ft from the shack, so it is NOT bonded to either
shack or house grounds. The garage/shack has about 8 driven rods --
three on the side by the entry/breaker panel, two more around the
perimeter, and three outside the shack. #4 runs around the perimeter,
picks up all the rods, runs up to the antenna panel about 2 ft off
ground. Steel conduit (EMT) brings power to multiple 120V and 240V
outlets below the operating desk.
At the house, I have three driven rods near the service entrance. There
were none when I bought the house -- a "ground" wire ran about 35 ft to
a spigot for a garden hose, which was fed by PVC pipe. :) Telco and CATV
grounds are bonded at the service entrance.
With respect to the tower -- coax shield should be bonded to the tower
top and bottom. From each tower leg, at least one driven rod, preferably
more spaced out from the tower a distance equal to at least the length
of the rod. Also a bond from the tower to the structural mesh within the
tower base. I do that with copper strap, using clamps for the tower legs
that prevent dissimilar metal issues. I think I got them from DX Eng.
73, Jim K9YC
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