My conduit tower runs (away from the house are only about a foot down.
Frost line IIRC is 36"
Photos near the bottom of the page.
http://www.rogerhalstead.com/ham_files/cablebox.htm. Heaving due to
frost has never been a problem. Codes do not apply as there is no power
other than the low voltage to the rotator. Locally, permits are not
required for ham towers and stations. Code does apply to electrical
circuits with permits required for new circuits, both 120 and 240 which
IIRC $25 for each breaker installed and must be inspected.
Buried power cables must be below the frost line. I buried the 240 feed
to the house 4' down in 4" conduit with an installed messenger cable.
The guys from Consumers were sure happy to see that messenger cable.
The ones near the house to the 100' 45G are down about a foot in the
back fill sand. There is 1' Styrofoam sheet over that so frost/freezing
isn't a problem. We buried 1" conduit, 1' above the power cables for
the cable and phone lines.
Our frost line is 36", but last winter the only frost was under the
driveways and roads. Two years ago there was only a few inches, which
thawed after a layer of snow was on it which left very soft soil.
I've been waiting to install the base of my LM470. It never dried
enough this summer to get the truck in. Now we are hoping for enough
frost to make the ground solid enough. We may end up spending extra (a
bunch) to have it pumped from the road. ~120-130 feet.
OTOH the culvert for our driveway wasn't buried deep enough. It took 10
years, but it gave us a speed bump high enough for small cars to bottom
out. Never had one hang up.<:-)) The county cleaned and deepened the
ditch and fixed our driveway. We had culvert installed and buried
(permit required, used local contractor) Now my wife won't be getting
the lawnmower stuck in the ditch and the yard looks a lot better.
--
73
Roger (K8RI)
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