[BC] Air-Dielectric Sections

[Phil Alexander]

On 5 Mar 2007 at 8:11, Andrew Skotdal wrote:

> If you have a 700 foot run of 3 inch air-dielectric line, I'm told that
> the maximum length per section is 400 feet.  If this is the case, has
> anyone encountered expansion and contraction issues at the joint where
> the two sections are combined?  We're planning on doing a sub-surface
> run in conduit.  I'm assuming we'll need a vault to get to the joint in
> the future, but is there anything else in terms of wear and tear that
> should be considered?

Note that a sub-surface run is (if deep enough) a fairly constant
temperature environment. Most of the temperature change will probably
result from cable loss and will appear on the inner conductor. The
bullet joining the inners of the connectors should be checked from 
time to time (every few years) for wear as should the ID's of the 
connector inner conductors themselves. Usually this is more a problem 
with rigid line, but it should not be overlooked. If the line power is
constant 24/7 wear may be minimal, but if it goes up and down 
frequently, as might be the case in an AM plant, then periodic 
inspection should be considered.

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