Re: what is the best wire for a perimeter alarm

[Jim <alarminex@xxxxxxx>]

On Sep 17, 11:32?am, "Bill" <bill190nos...@xxxxxxxxx> wrote:
> "Sue"  wrote in message
> > My brother-in-law, who is an electrical engineer, would wake up from a nap
> > in his easy chair and walk to the kitchen thru the beam of his PIR only to
> > have his alarm start wailing.  "Wait", he said to himself, "I didn't arm
> > the system!"  After this happened several times, he began to wonder, what
> > in the heck is going on that could arm my alarm?  One evening immediately
> > after this happened, he mosied outdoors, and lo and behold he could hear
> > his neighbor talking on his ham radio.  Said neighbor had antennas all
> > over the outside of his house.  Ron had not used shielded wire for his
> > alarm system. He re-wired that weekend, and problem was solved.
>
> I had a problem with a TV remote extender not working (Operate the TV remote
> from another room). So I enclosed the transmitter in a metal box, receiver
> in another metal box (Faraday cages), leaving small holes for the light to
> go through, then connected a shielded coax cable between them. Then it
> worked just fine.
>
> The receiver had a light which indicated it was receiving a signal from the
> transmitter. Well this light was going almost constantly even though the
> transmitter was off! And this was jamming the real signals so the extender
> could not work. After I shielded everything (from external RF), the light on
> the receiver stayed dark unless the transmitter was activated.
>
> Anyway lots of RF around - at least where I live...

If you have an RF problem, then it may (meaning maybe)  be addressed
with shielded wire. But there are other solutions that might work that
would be much simpler to impliment.


The point that is trying to be made regarding shieled wire is that it
may solve specific problems. However, if used indiscriminately , it
can cause problems. Even when called for, it can cause other problems
that have to be addressed, in addtion to the original problem. If a
mfg has specific requirements to use shielded wire from feed back from
the field or by design, they'll certainly tell you to use it.
Otherwise, if not recommended, the overwhelming odds in favor of NOT
having a problems is the best way to proceed.

Use what the manufacturer recommends and if you have a problem,
address the specific problem and if it calls for a shield or a choke
or a capacitor ..... try what ever is recommended until the problem is
solved. If you start out with solutions to problems that don't exits,
you'll greatly increase the possiblity of creating issues that
wouldn't have existed had you followed the mfg's recommedations.

Whew!