Re: Conduits in a trench

[RickH <passport@xxxxxxxxxxxxxxxxxxxxx>]

On Nov 25, 2:01 pm, "CWatters" <colin.watt...@xxxxxxxxxxxxxxxxxxx>
wrote:
> "Larry" <inva...@xxxxxxxxxxx> wrote in message
>
> news:w62dnd0mj52OEtTanZ2dnUVZ_t-gnZ2d@xxxxxxxxxxxxxxx
>
>
>
>
>
> > 42 wrote:
> > > I will be having two conduits in a trench. One will be have 4
> conductors,
> > > 220vac + neutral + ground. The second will have probably 2 cat 5/6 for
> phone
> > > and possibly HA and a RG6 for cable TV.
> > > The trench is 24" wide. If I keep the two conduits on opposite sides of
> the
> > > trench while backfilling, will the 24" of soil be enough to prevent
> > > interference problems. I could dig 2 trenches yards apart, but of course
> I'd
> > > rather not. The total length is about 125'. They will be 3'-4'
> underground.
> > > TIA
>
> > That should be fine.  I've done the same thing with a 16" trench and
> > didn't have any problems.  Cat 5/6 uses balanced pairs which are pretty
> > immune to interference.  RG6 is, of course, shielded.  If what you've
> > hooked the 240vac up to produces too much interference, you can always
> > use shielded cat 5/6 but I doubt you'll have to.
> > --
>
> > Larry
> > rapp at lmr dot com
>
> Should be ok for interefrrence that's directly coupled but bear in mind the
> RG6 may form a big loop.
>
> Any high power machinery about?- Hide quoted text -
>
> - Show quoted text -

If the RG6 does form a big ground loop, then make sure the shield is
only grounded at one end not both ends, (IOW "lift" or break the
ground at one end).  You'll still have a ground, but there will be no
potential for AC to flow in the shield due to differing ground
impedances at each end.  Same if you go with shielded cat5.