[BC] Air-Dielectric Sections

[Phil Alexander]

On 5 Mar 2007 at 11:31, Mike McCarthy wrote:

> I'm thinking hydraulic sub-soil conditions where freeze/thaw or other 
> geological pressures creates a force on a rock/bolder and will bust the PVC 
> clear through and compressing the line.  Doing that to a 5" #11 or #13 
> fiber duct would be brutally difficult since the walls are over 1/2" thick.

Exactly. And rodents don't chew through so easily as PVC.
> 
> On the 3" line we installed for our project, duct was about $2/ft. compared 
> to $0.50/ft. for grey electrical PVC in quantity.  

But if you protect the PVC with field tile or concrete conduit, as I believe
is essential, the cost saving evaporates, and then some.

> But we made up for that 
> cost in labor savings.  It took one day for two men to lay out 3000 ft. of 
> duct....on 6 spools.  Try that with conduit.

Clearly, you have the best idea - using fiber duct, but depending on the
situation (e.g. if an AM) I'd strongly consider directional boring and the
corrugated conduit they use.

> I read it as an open statement not offering preference to one type of line 
> over the other.

OK but the idea of using 3-1/8" rigid in horizontal u/g run seems bizarre to 
me, but maybe that's just me. <g>


---------------------------------------------
Phil Alexander, CSRE, AMD
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037