Topband: underground cables question

Wes Attaway (N5WA) wesattaway at
Thu Oct 5 11:44:07 EDT 2017

I installed 4 runs of BuryFlex through my slab and then out into the
backyard about 15-years ago (when we built a new house) and it is still
working fine.  I have conduit through the slab (open at both ends) but the
cable is direct buried out in the yard (about 24" deep).

Wes Attaway (N5WA)
(318) 393-3289 - Shreveport, LA
Computer/Cellphone Forensics
-----Original Message-----
From: Topband [mailto:topband-bounces at] On Behalf Of Dale
Sent: Thursday, October 05, 2017 10:13 AM
Cc: topband at
Subject: Re: Topband: underground cables question

must have to do with the annual rainfall.

I too come from 30+ years in telco and radio comm. There are 12 runs of 6 in
conduit between building on one campus, and a number of others around that
are still dry after being there for 20+ years. And the conduit, I am
speaking of is PVC TUBE..   pretty much the same stuff that carries the
water into your house. IF someone wants to use emt conduit, then that is the
description that Guy so aptly describes. NOT a good deal. AND it isn't rated
for water per code in the electrical code either. I have seen where
squirrels somehow managed to work the metal conduit hard enough with the
weather helping, to access the coax inside.. they didn't much like the
sticky goo inside.. but that didn't stop them from eating enough to short
the coax..   and of course Muphy made it an intermittent short.

Have a great day,
--... ...-- Dale - WC7S in Wy

"Actions speak louder than words"
1856 - Abraham Lincoln

From: guyk2av at <guyk2av at> on behalf of Guy Olinger K2AV
<k2av.guy at>
Sent: Thursday, October 5, 2017 8:12 AM
To: Dale Putnam
Cc: topband at
Subject: Re: Topband: underground cables question

Coming from an ancient Telco background which included keeping microwave
waveguides dry for AT&T, unless you are willing to pressurize the conduit at
one end and allow air to exit at the other, AND insure that the air is dry
enough to not condensate at your coldest possible ground temperature, or run
it with an unbroken slope to a point where water drains without pumping and
or can be suctioned, then make these assumptions:

1) Permanent performance and very long life is desired and outweighs cost.
If you move a lot and are putting up stuff at rental housing you probably
need not worry. Just remember to start with new coax and cable at the new
rental place. Throw away the old stuff. Then mark this read and move on to
the next posting. If you think you are retiring at your place of residence,
and if lucky want it to work without a worry for the next 30 years absent
direct lightning strike, then read on.

2) All conduits will fill with water. That is their NATURAL state unless you
specifically and effectively mitigate it. At any time other than first
installed, filled with water is their most probable state.

This leaves the main usefulnesses of the conduit as

a) Critter protection, and

b) Cable replacement, if the conduit is large enough and water-proof pull
ropes are left in conduit,  a method of adding or replacing cables that
avoids redigging and leaving deprecated cable in the ground. These are
significant long-term advantages, and many find those more than enough
reason to use them. However.......

3) Even in conduit all cables must have permanent, water-proof jacketing.
Most cable has jacketing that is not rated for permanent submersion, meant
for indoor use.

Polyethelyne (PE) jacketed or hardline cable is really the only commonly
available choice for coax with portions permanently submerged. Flooded is
nice, but probably overkill INSIDE CONDUIT if the jacketing is PE or other
permanently waterproof material. ***RG213 does NOT conform.*** Any
miscellaneous plastics do not conform. There are cables manufactured with
ham-uncommon materials to telephone company specifications, FOR DELIVERY TO
TELCO, that have all the water stuff worked out just fine. But BEWARE
knockoffs and batches for retail that mfr knows will never be sample tested
by telco. Or for that matter cable that failed telco tests and was put on
the retail market to recover costs.

High current rotator motor leads (as opposed to control leads) should use
the commonly available UG series direct-buriable power wiring available at
home improvement stores. Less voltage drop, permanent and rated for wet

4) splices or cable terminations should be made indoors and elevated where
waterproofing failure will not allow water to get inside the PE jacketing.
Some manufactured multiconductor cables will have BOTH external and internal
insulation PE or teflon. Do not locate splices in conduit. You're just
asking for it. Even if 9 out of 10 get away with it, be assured you will be
# 10. Murphy KNOWS all you've done, knows all the contest and DXpedition
dates, AND has a malevolent nature.

73, Guy K2AV

On Thu, Oct 5, 2017 at 8:49 AM, Dale Putnam
<daleputnam at<mailto:daleputnam at>> wrote:
I agree with Ken, with only one option, and that would be if the conduit is
open on both ends.. allowing free air flow thru. That situation, MAY help
dry the water from sitting on the cable, depending on the average humidity
at the underground temp. Warm air from inside.. to cold air outside may not
work out well either.

Have a great day,
--... ...-- Dale - WC7S in Wy

"Actions speak louder than words"
1856 - Abraham Lincoln

From: Topband
<topband-bounces at<mailto:topband-bounces at>> on
behalf of Ken Claerbout <k4zw at<mailto:k4zw at>>
Sent: Thursday, October 5, 2017 6:19 AM
To: topband at<mailto:topband at>
Subject: Re: Topband: underground cables question

As you have found out, it's impossible to keep water out of a conduit like
that.  I use direct bury cabling and put it directly in the ground.  Granted
the cable is flooded, but putting in back in the conduit ensures it will sit
in some water, something I would try to avoid.

Ken K4ZW

-----Original Message-----
From: John
<beaumonts at<mailto:beaumonts at>>
To: topband <topband at<mailto:topband at>>
Sent: Thu, Oct 5, 2017 4:11 am
Subject: Topband: underground cables question

Hi all, some  years ago I buried a 4 inch conduit about a foot deep in my
field , inside I run a control wire and a coax line RG213 to a 160 m
vertical the feeder was a total of 5/4 wavelength long about half of it in
the conduit, it was used as one line for a pair of verticals spaced 5/8 wave
apart. When first installed it worked very good but after a while I noticed
it dropped off and I suspected water ingress. An insulation test with 1000v
from my electricians test equipment showed indeed a fall in insulation

So my question is I have a couple of large reels of commscope F1160 BEF
flooded 75 ohm
do you think I could put it in the same conduit which has allowed some water
in or would you make alternative arrangements . I realise it a direct bury
coax but appreciate advice.

I wish to get the two verticals going again will use 1 X 3/4 line above
ground 1x5/4 line part in conduit and a 1/2 wave to switch in and out above


John Beaumont

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