Re: shielding low voltage wire, running low voltage wires aside 12-2 romex

[Frank Olson <use_the_email_links@xxxxxxxxxxxxxxxxxxxxxx>]

Robert L Bass wrote:
>> Thanks for the tips.  I've been trying to maintain separation in all cases but as several mentioned, it's nearly impossible in an older (late 1800's) home to do this in all cases.  12" of separation sounds ridiculous especially when studs are often 16" or less on center.  You can only drill so many holes before you are doing more structural damage than necessary.  I thought about testing it by wrapping some low voltage wire around some hot romex and testing throughput on the low voltage.  Has this been done and published before?
>
> John,
>
> ....  For example, I installed a security system in an older home in CT years
ago.  Some time later an someone else ran new 110VAC cables right next
to one of my keypad (data) runs.  Every so often one of the keypads
would operate erratically.  It didn't start happening immediately and it
wasn't all the time either.
>
> On the first call I simply swapped out the pad, checked to see if it was OK and left.  Shortly thereafter I got a call that the system was still having problems.  The panel seemed OK because the other keypads were working.  Upon investigation I found the new Romex cable lying practically on top of my data cable.  I moved my cable over a couple of feet and the problem was solved.
>
> I've also serviced numerous systems which we took over from competitors who couldn't fix problems.  If the client mentioned keypads not responding or giving wrong indications, we'd disconnect the data cables and meter them.  On a fair number of occasions we found AC voltage being inducted into the security system cables.  Almost invariably rerouting a few cables solved the problems.
>
> I've wired quite a few older homes, John.  One of them originally belonged to Sebastian Shallus, brother of Jacob Shallus.  History buffs will tell you how old that house is.  It was moved a number of years ago to North Canton, Connecticut.  If you need help figuring ways to wire an older home I'd be glad to share some techniques with you.  I promise not to suggest anything that will weaken the structure.  Call when you have some time (my phone is in my sig line) and I'll try to help.
>

<snipped>  This is another installation fairy tale.  If AC inductance
was present on *ANY* of the keypad "data runs", it would affect the
entire system (and not just one or two keypads).  The keypad data
connection (or keybus) is a common termination point on every alarm
system manufactured.  A measurable AC voltage (which Bass goes on to
state he had) on a single "data line" would therefore "crash" the entire
system.  If you believe this man can really "help" you, then I have a
bridge you can buy.