Careful with the backfill! I wasn't careful enough with backfill of one
of my 4 inch PVC conduits and cracked it later after backfill during wet
weather, most likely a sharp rock. Ground water infiltrated the conduit
copiously putting several gal per minute of water onto a metal barn's
slab floor. Water came out inside the building over 2 ft above the
floor. Barn is down slope from some tower sites. Luckily I hadn't
pulled any cables yet and just sleeved all the wires in flexible
irrigation tubing good for 100 PSI at 73F before pulling into the
conduit. It won't get that hot underground and the head of pressure is
significantly less than 100 PSI. The irrigation tubing is quite flexible
and comes in 100 ft rolls for $12.50 per roll at the big box stores and
can be spliced for longer runs.
Best wishes for a job well done.
Patrick NJ5G
On 9/2/2016 2:59 PM, Mitch wrote:
I'll answer all in one post.
This is a new installation. The feed line exits the radio room on the West
wall, goes underground, through the house West foundation wall, through a
little over 70ft of crawl space, out through the East foundation wall
again, under the gravel drive way that goes to the back of the property then
runs approximately 200ft under the driveway along the east side out to where
the 45 sweep will be, the approximately 80ft to the tower. I thought about
just direct burying it, but wanted the extra protection of conduit due to
the driveway traffic. This driveway sees cars, diesel pick up trucks, farm
tractors, sometimes large trucks and heavy equipment. There is no other
route the coax can take. I also do not plan on the coax being more than
about 2ft down due to a large cobble rock layer at about that depth. The
earth above that is silty sand with some samll rocks. Could the hardline
survive under these conditions, probably, but I will feel a lot better with
it in conduit. I can always run smaller conduit for the control lines. These
conditions and limitations are what they are. Again, no other options for
the routing to the tower.
If necessary, I can add the two end sweeps after the hardline has been
pulled. That should alleviate some of the force necessary to get it most of
the way. Then slip on the end sweeps once its in place. Or just slide the
conduit sections on one at a time until it is all encased. Would make it
easier to add the control lines at the same time too. Just a lot more work
versus pulling through an already buried conduit.
I have a large heavy duty pulling grip that will be used to pull the
hardline and other cables through the conduit. This should eliminate it
hanging up on the ends of the conduit.
Mitch KJ7JA
------------------------------
Message: 7
Date: Fri, 2 Sep 2016 14:36:45 -0400
From: "john@kk9a.com" <john@kk9a.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Pulling long length of 7/8 hardline in
conduit
Message-ID: <d16401467cdc58ea6aa7fea9b51c87d7.squirrel@www11.qth.com>
Content-Type: text/plain;charset=iso-8859-1
This will be very tough. If this is a new installation I would just direct
bury the Heliax. If the conduit is already buried I would at least dig up
the ends and so that they have no bends. I think it is easier to fish
everything at once but I do not fish Heliax though my conduits. I would
fish the new pull line when you run the wires rather than try to get a mouse
though a partially filled tube.
John KK9A
To: <towertalk@contesting.com>
Subject: [TowerTalk] Pulling long length of 7/8 hardline in conduit
From: "Mitch" <mskobier@charter.net>
Date: Fri, 2 Sep 2016 10:54:12 -0700
All,
I'm looking for anyones experience with pulling a long
(almost 400ft) length of 7/8" hardline in underground conduit. I have 4"
conduit which will have a number of sweeps in it. Here's how it will lay
out. The first 90 degree sweep is where the hardline goes down from the
junction box into the ground. Then it runs approximately 80ft straight, then
hits another 90 degree sweep, then runs mostly straight approximately 230ft
where it hits a 45 degree sweep, then runs approximately 60ft to the final
90 degree sweep where it turns vertical up into the junction box at the
tower. I'm concerned with possible kinking of the hardline making that many
turns. I can possibly not use the 90 degree sweeps at each end during the
pulling, but it would be nice to do it all without having to make conduit
connections after the hardline is in place. I plan on using lots of wire
pulling lubricant during the pull. I cannot re-route the hardline/conduit.
This is the only way I can run the hardline to the tower. Has anyone on the
list ever pulled hardline through a number of sweeps?. There will eventually
be a number of other coaxes and control cables in the same conduit. I plan
on pulling the hardline first, so I have the most room, then I will run a
mouse through the conduit to avoid having the remaining cables trying to
wrap around the hardline and getting wedged under or stuck by the hardline.
Thanks in advance for any and all help.
Mitch KJ7JA
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