Greetings,
It is also considered good practice to maintain at least a 300mm vertical
separation between conduits in trenches where different voltages or services
are concerned.
This is common sense to reduce stray coupling between various cables, for
example noise coupling from AC lines to antenna lines or rotator control
lines.
You should also provide 150mm offsets in the conduits every 50 metres or so,
especially if your environment has a high range of temperatures or is
subject to significant soil movement.
Cheers
Peter VK3QI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
jimlux
Sent: Monday, 18 April 2016 10:37 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] RF and AC Cables In Buried PVC
On 4/17/16 6:17 PM, Tony wrote:
> All:
>
> I'm in the process of getting materials together to run both RF and AC
> service cables from the house to a shed. I was going to install
> separate schedule 80 PVC pipes, but before I do, I was wondering if
> it's possible to run both types of cable in the same pipe? Are there
> any drawbacks, safety or otherwise when running both through a single
pipe?
You generally should not run "low voltage" circuits in the same conduit as
AC power (in fact, the electrical code prohibits it). The risk is of the AC
line shorting to the low voltage circuits: since low voltage circuits are
generally limited energy, they don't have over current protection, safety
bonding, etc., so a short might flow enough current to start a fire or shock
someone. (and, of course, blow up your receiver and transmitter)
There are some techniques that would make it legal, but would require more
time to explain to the inspector than it would take to just lay the second
conduit in the same trench as the first one.
>
> The RF cables are for a VHF / UHF array - the AC cables will power the
> lighting inside the shed.
>
> Thanks,
>
> 73, Tony
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