Re: Punchdown blocks

[Keith Doxey <keith.doxey@xxxxxxx>]

Hi Nigel,

I wouldnt use krone strips for Ethernet. Might be OK for 10Mbps but the
CAT5 100Mbps spec states that the wire should be seperated by no more than
1cm. To wire a Krone strip you separate by at least 3cm. Also because there
are 10 pairs per strip and 4 pairs in a CAT5 you end up terminating the
cables like this (pair numbers only are shown)
1234123412
3412341234
1234123412
3412341234

Inserter Wire 2A is the tool used by all BT engineers and at around 15 quid
is well worth the investment. The difference between a 237A and 237B is
that the A type has break jacks between the upper and lower row of
contacts. This can be used to disconnect wiring temporarily for testing by
inserting a special plastic wedge, or more importantly, you can plug
lightning arrestors into the strips to protect your goodies.

The "2 wires per contact" mustnt be exceeded as the third wire
will only
just be gripped by the IDC connector and a bad joint will result. Also
NEVER use different sizes of wire in the same IDC as the larger wire will
force the contacts apart and the smaller wire will have a bad connection.

Terminate just the fixed cable on the top, and jumper to the bottom, daisy
chaining is OK as you will only have 2 wires in each connector.

Keep the cable sheaths to the left or right of the metal cage that the
strips attach to as there is a wiring loop in the centre of the krone strip
that almost touches the chassis. Be careful not to trap the wires as you
insert the strip into the frame.

Also when you play with the wiring tool to see how the cutter operates,
have a box of plasters ready coz it bleeds a lot when you nip your fingers
in the blades :-((

If they list the 500 series of box conns have a look at them. Probably
mucho expensivo but very nice. Metal cabinets with a hinged door and lots
of room inside. Although they are quite a bit more than the 301A you will
only need one and it may come reasonably close on price.

Any more question feel free to ask.
The worst I could do is ignore you....but I'm too nice a guy for that :-))

Keith

Keith Doxey
http://www.btinternet.com/~krazy.keith
Krazy Keith's World of DIY Home Automation

-----Original Message-----
From:	Nigel Orr [SMTP:nigel.orr@xxxxxxx]
Sent:	Thursday, July 29, 1999 2:52 PM
To:	ukha_d@xxxxxxx
Subject:	[ukha_d] Re: Punchdown blocks

At 14:15 29/07/99 +0100, you wrote:
>For permanent wiring that will never or seldomly be altered eg
Hardwired
>Keypads and sensors then I would use a BT style connection box (Box
Conn
>301A) fitted with Krone 237 strips.

That's what I was looking at- just wanted to check it was what is used for
Ethernet too...

>The Box Conn and Krone strips are availabl from Farnell etc.

Is the price there reasonable for small quantities?  Farnell & RS are
always my first port of call, but there's usually someone _much_ cheaper if
you know where to look...

>Remember that the solid cored wire can only be flexed a few time before
it
>starts to break so you want to ensure that all your installed wire is
fixed
>firmly into place with any patching done by means of a patch panel or
>jumpers on a box conn. It also looks much neater that way. :-))

I will bring all the fixed wiring down to the Krone block, then add local
links and jumps as required- they will all be short, so easily replaced if
they 'wear out'- I don't see any reason why I will need to disconnect the
fixed house wiring.  At this stage, I won't be adding any patch panels,
until I see what I really need...

Now for the long list of questions, where you wish you had forgotten to
reply this time too ;-)

Not being a BT-trained person- are there any useful publications/hints/tips
to make it all fit in neatly and look nice at the end?  I can cope with
wiring up 80-pair audio stageboxes, but every system has different 'tricks'
which you find as you go on... I presume the labelholders clip on top of
the blocks?  I'm planning to order some "Jumper Rings 37B" as
well, to save
having ty-raps everywhere...

I also noticed (in Farnell) that "All contacts can accept two wires of
equal size", which presumably means you can have 4 wires commoned on
each
of 20 positions (10 pairs).  Is this correct?  Is it often used, or best
avoided, to have 2 wires per contact?

What is the difference between 237A (10 pair disconnection contacts and
237B) (10 pair connection contacts) (RS sell both- Farnell offer 237A in
blue or cream!)

I will basically have 4 sets of wiring- Screened HA, Screened A/V, UTP
Telephone and UTP data.  Each will need about 30 pairs.  Would 'best
practice' be to keep each in its own 301A box (plenty of room for
expansion!) or would they normally be 'doubled up'- eg Telephone and A/V in
one 301A?  I will probably go for a box each (especially at RS's prices),
but if there are any corners which should be cut, I may as well do so now!

And finally (for now), is the 2A tool in Farnell a reasonable choice?  I
would like one that can cut the wire ends or not, as required, and that
will be reasonably easy to use and last well(even though I'll 'only' reckon
on about 100-150 pairs initially)

Thanks,

Nigel
--
Nigel Orr                  Research Associate   O   ______
Underwater Acoustics Group,              o / o    \_/(
Dept of Electrical and Electronic Engineering     (_   <   _ (
University of Newcastle Upon Tyne             \______/ \(

------------------------------------------------------------------------
Click Here to apply for a NextCard Internet Visa and start earning
FREE travel in HALF the time with the NextCard Rew@rds Program.
http://clickhere.egroups.com/click/449


eGroups.com home: http://www.egroups.com/group/ukha_d
http://www.egroups.com - Simplifying
group communications





------------------------------------------------------------------------
GET $10 OFF ANY ORDER @ healthshop.com! No min. purchase req.
Save on vitamins & supplements. Use coupon code: EGROUPS at checkout
http://clickhere.egroups.com/click/615


eGroups.com home: http://www.egroups.com/group/ukha_d
http://www.egroups.com - Simplifying
group communications