[TowerTalk] burying cable

[Roger (K8RI) on TT]

It depends on the soil, the moisture content and the freeze thaw rate 
and cycles.

I have a man door on the shop where they did not go deep enough with the 
sand over which we poured the stoop, or porch floor.  In the summer that 
door clears the concrete by several inches. In the winter I can only 
open the door about 30 degrees before it hits the concrete.  If I had 
direct bury coax coming up through that, it would pull it apart.
The soil is either sand, clay, or peat with a high moisture content.  
This year the frost may have made 10 to 12". Code calls for either 30, 
or 36" deep for water lines.  The frost line may move up and down 4 or 5 
time in our winters and sometime it hardly moves all winter.

So coax around here is pulled through 4 or 5" conduit although the 5" is 
1/8th inch wall sewer pipe. All 90 deg bends are two 45 deg sweeps. Even 
in the harshest winters the frost is no where that deep EXCEPT  under 
driveways and sidewalks.

Trenching 4 to 5' is quite easy if you do not have a lot of rocks.  I 
rented a skid steer trencher and did about 130' diagonally across the 
driveway from the power pole to the meter on the house.  I think it took 
less than an hour with the driveway being the slowest.  IIRC I snapped a 
shear pin in there somewhere.  I put  4" conduit down 4' and the cable 
feed a foot above that in 1/2" PVC.  The crew was really happy to see 
tht pull line already in place.  They used it to pull their half inch (I 
think).  IIRC they didn't even bother with pull/wire soap.

  73

Roger (K8RI)


On 6/20/2015 7:23 PM, William Hein wrote:
> As I sweat through digging (with a trencher and by hand) trenches putting
> Commscope AVA7-50 hardline (eBay deal) and control lines from the shack to
> a couple of towers here I mused on whether or not frost line has an
> application to burying coax cable and low voltage control lines.
>
> I get why one buries water pipes below the frost line as well as house
> foundations, by why radio cables? Is frost heave an issue for cables if one
> has some slack on either line of the line?
>
> 73
>
> Bill AA7XXT
> Glade Park CO
> DM59pa
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-- 

73

Roger (K8RI)


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