Re: CAT-5 wiring details

[Nigel Orr <Nigel.Orr@xxxxxxx>]

At 15:33 27/09/00 +0000, you wrote:
>My requirements are phone and data, IR transmission and reception,

All fine on cat-5, keep separate cables for phone, data, IR, (and audio,
video, spares, spares and some more spares)

>sensor and control signals for Homevision

Dunno.

>and sensor and doorstation
>signals to Comfort.

Sensors, fine with cat-5.  Doorstation, I've run it or the keypad down 15m
of unscreened cat-5 temporarily to try it out, on a couple of routes, with
no audible hum or communication problems.  However, I wouldn't risk
installing it permanently like that, your route could easily be noisier
than mine!  Run some screened cable, FTP/STP would be fine (foil screened
twisted pair/ screened twisted pair) or any other screened cable.

I presume the reason that shielded is recommended is that the voice and mic
lines are single-ended.  If they weren't, then you wouldn't have a spare
pair in the cable to 'double up' the 12V and 0V lines

>I have read different advice regarding Cat-5 cables. Should I bite
>the bullet and run shielded cable thoughout to allow flexibility.

Not unless you are in a very noisy area (eg large transmitters or heavy
industry nearby), I would suggest.  I was planning to run shielded for A/V,
but it's currently unbalanced unshielded, and the noise is barely
audible.  If I make it balanced at a later time, that should improve
further.  As someone has posted, there are also some (very slight)
disadvantages to shielded apart from the cost.

>If I did this would this be OK for Comfort sensors and doorstations
>or does COmfort really need 8 core screened alarm cable?

It would be fine with screened cat5 instead.

>Should I look at having a patch panel that alows me to reconfigure
>*any* socket or should I just do this with phone, data and spares?

I've used Krone terminals for everything at the wiring centre, so it's
reconfigurable in a short time.  I've got 20 rows, each can have up to 10
pairs of cables.  I've used appropriate wall plates for each outlet, eg
phonos for video, BT sockets for phones.  They're all replacable with 5
minutes work, either soldering or punchdown connections, and realistically
they're unlikely to ever change function.

The Ethernet cables are as yet unterminated, but will go to a patchbay
instead of the Krone blocks.  The idea of having standard RJ type sockets
everywhere with a big patch panel and adaptors required for everything
doesn't appeal to me, but I believe others like that more...

>Would it be safer to hardwire sensors in to Comfort and accept that
>their positions would always be fixed?

Mine go through the Krone blocks, so they are reconfigurable without
worrying about wires breaking in screw terminals etc but will probably
never be moved.  What it does mean is that if, for instance, I was
replacing Comfort (seems very unlikely, but you never know!), I could just
pull all the Comfort to Krone cables, put in the new system, and link it up
to the Krone blocks.  That is especially useful if the new system isn't in
exactly the same location as the old, as otherwise sensor wires might have
to be extended or replaced.

The only downsides are a slight cost increase and that the Krone wiring box
is
now a point of attack on the burglar alarm wiring (if you're expecting
sophisticated burglars, and/or the box is exposed).  You can always fit a
tamper switch of some kind though...

>Should I look at Cat-6 with an eye to the future? Should I run some
>sort of fiber at the same time? I don't know too much about this!

Nah, wouldn't bother.  Cat-5 will do up to 1Gbit, as Mark has said, and
there's so much of it installed in commercial premises that there will be a
good reason for future systems to run on it too.  Remember initially it was
only good for 10Mbit, and phone lines used to have a maximum of about 14.4k
and now can do 56k and even ADSL... there's always some genius somewhere
who will figure out how to squeeze some more in!

Even if you do need more cables, the cat5 will always be fine for a/v,
phone etc, and you might even be able to use a spare cat5 to pull a newer
cable for some runs.  Similarly for fibre, it's been touted for as long as
I can remember as the 'next big thing', but it's applications are still
quite narrow for anything other than large-scale telecoms.  Wonderful stuff
though,  I'd probably even say "you can never have too much
fibre" if there
was anything to actually connect it to!  Basically, all the advantages of
cable, with no induced interference, and loads of capacity.

And run several spares to each location.  If it needs 1, run 2, if it needs
more than 5, run a couple of spares etc etc.

There's some more info, mainly about the practicalities of running cables,
on http://ha.orrs.net under
'retro-wiring', with a load of links at the
bottom to useful info.

Nigel


-------------------------- eGroups Sponsor -------------------------~-~>
Get a NextCard Visa with rates as low as 2.99% Intro APR!
1.  Fill in the brief application
2.  Get approval decisions in 30 seconds!
http://click.egroups.com/1/9334/9/_/2065/_/970125673/
---------------------------------------------------------------------_->