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If you
are choosing STP on the basis that it is more robust for pulling then you
are
using the wrong techniques for pulling cables. Millions of miles of CAT3,
CAT5
and Alarm cable have been pulled in over the years without any problems. If
you
are using so much force that you feel the added strength of a foil screen
will
protect your cables you are living dangerously.
I
cant
dispute Alan's claim about stranded cabe as all alarm installs I have seen
are
stranded and a mate who works for an alarm company told me it was because
solid
wire broke too often.
Solid
wire does have some drawbacks....
1. It
isnt flexible. - Bending it too often will cause it to
break
2. It
CAN be unreliable under screw terminals.
The
secret to terminating solid wire is to only wrap it 180 degrees round the
screw.
The mistake a lot of people make it to do a complete turn around the screw.
This
means the wire rests on itself and as you tighten the screw it cuts through
itself and breaks. I used telephone cable for my alarm with no problems at
all
(but only because I had a lot of it and no alarm cable). It can also be a
problem putting two solid conductors under the same crews as the same
cutting
action can apply. If you ned multiple solid wires under the same screw,
twist
them together first and DONT overtighten the screw.
Likewise, stranded cable is not ideally suited to
Insulation Displacement Connectors (IDC) aka Punch Down because instead of
the
blades cutting into the wire as they do with a solid conductor to form a
cold
weld, the individual strands move so you only end up with surface contact
instead.
IDC's
should only have one or two cables terminated and both should be the same
type
and size of conductor otherwise poor connection will
result.
Use
the proper cable AND tools for the job.
Fixed
Data and Telephone wiring = SOLID
Patch
cords and Alarm Wiring = STRANDED
HTH
Keith
You should not be using solid core cable for
the
alarm, there is a British Standard for alarm cable can't remember the
number
but it should be stranded. You may find if you use it that an alarm company
will not take on responsibility for the system if you need a Police
connection
or for insurance purposes.
Alancc
----- Original Message -----
Sent: Friday, December 21, 2001 7:44
PM
Subject: RE: [ukha_d] House wiring -
follow up
OK I bow to my peers superior knowledge here. I tend to use STP cable
instead of shielded alarm cable as it is more robust for pulling (than
alarm
cable). Personally I would drag STP everywhere but if my peers say that
this
may lead to problems then I would advise UTP. BUT I would advise either UTP
or shielded alarm cable for your alarm pannel and sensors.
Simon
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