CAT5 and Cross-Connects

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 Question by Tim Fitzgerald posted 09 Jul 2000
 CAT5 and Cross-Connects
Great site!

I just opened a new office with about 150 cat5 runs. Starting at the wall jack in each office, the cables run back to our server room and are terminated on a 110 block. They are then cross connected to another 110 block using two pair cross connect wire. From there, they run back to our Cisco switch.

My question is will this meet the cat5 wiring specification? There is about 10 to 15 feet of cross connect wire between the two 110 blocks. Is this standard? In the past, I have only seen the runs go directly into a Ortronics or Lucent patch panel.

Thanks in advance!

All the best,

Tim
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 Answer by Dmitri Abaimov posted 10 Jul 2000
Dear Tim,

It looks pretty much like your system is OK.

The systems you've seen before were using so-called 'interconnection' scheme while yours called 'cross-connection'.

Despite it has one more connection point, it is absolutely legal, and in fact few years ago 'cross-connection' was the only cross scheme allowed by TIA/EIA-568 standard.

So you can call it 'CAT5 compliant' provided by all the rest of the specs are met:

All the hardware is specified as CAT5 (or better) compliant;

All the cable runs are within 90 meters (295 ft) limit;

Combined length of work area patch cords plus cross wires should not exceed 10 meters;

Everything is installed perfectly as per vendor's instructions;

I would strongly advise you to consider one more point though. There is a fact that using cross-wires instead of 110 patch cords, you are significantly limiting 110 cross - connect blocks' lifetime. Those blocks have limit of only 10 connections made with impact tool and 250 matings when 110 patch cord is used. And I would add that you have to be very careful if you really want the blocks to survive those 10 impacts. So I would recommend buying some 110 patch cords for at least those frequently patched cross-fields.

With best regards,
Dmitri Abaimov, RCDD

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