On a much more basic level than some of the other replies - and for my
simple, straight 40-foot run:
1. Be certain to use "sweeps" rather than "90 angle" fittings. The sweeps
provide a more gentle curve.
2. Be very certain you have drainage from everywhere in the pipe. Have it
slope and/or drill holes in the bottom and set it on a little gravel. Place
plastic over it when filling in the trench so the gravel is not packed with
dirt. Dig a little dry well under the ends if you depend on sloping it. The
conduit will eventually fill with water, no matter how you seal it. Use a
good level to determine slope; do not try to eyeball it. (I ignored this
advice and had to dig up my conduit and set it again.)
3. Be certain to leave a good "messenger" rope in the conduit, tied at both
ends, and at least twice as long as the conduit. I found it better to NOT
mix this with the initial cable feed to avoid having it intertwined with
the initial cables. I placed tension on the permanent messenger cable (to
hold it against the top of the conduit) while feeding the initial cables
through. This allowed the messenger line to run freely after the initial
cables were in place. I used a 1/4-inch dacron line for the messenger.
4. I ran two #12 insulated wires outside the conduit (and mostly under it)
to server as an additional link for the common ground just outside the
house. This was probably not needed, but it seemed a good idea at the time.
5. I have 180-degree fittings at both ends, to keep rain out. These are not
glued on. I remove them when pulling cables, although the cables (after
emerging from the conduit) run through these fittings.
6. Before feeding cables, lay them side by side in an orderly way and try
to feed them into the conduit this way. This will make it much easier to
pull one of them later. If the cables twist around each other inside the
conduit, pulling one becomes very difficult.
7. I have three coax and three control cables in a 3" PVC pipe. This makes
a small bundle lying in the pipe. Do not even think about using anything
smaller than 3" pipe..
8. The top of my conduit is only about 6 inches deep in some places and
averages about 10 inches deep. Not very deep. (I dug it by hand, in "soil"
that is hard clay and shale. I am a bit lazy, also.) This seems deep enough
for grass to grow normally on top.
These are trivial points, but might help with a first-time buried conduit.
Bill - W2WO
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