568A vs. 568B

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 Question by Peter Oster posted 25 Mar 2004
 568A vs. 568B
I am a home builder self performing structured cabling in a new house. I have installed 22 Cat5e jacks throughout the house (two per wall plate) and terminated these home run cables onto a Leviton 24 port patch panel (19" rack mount type patch panel) all following 568B "as Anixter advised me to use 568B as it is most commonly used". I have bought a Leviton Line Distribution Board Voice/Data module (without their patching jacks) for conversion from 110 demarcation to multiple Cat5e jacks and then patch to the Leviton patch panel. Now I find out from Leviton that the Voice/Data module is 568A as Leviton says "residential Cat5e is to be wired to 568A standard (not 568B)".
How does a laptop computer that I use in office "commercial network 568B" and then bring this same laptop computer to my home "residential network568A" work since the cable terminations patterns are diiferent on pairs two and three?
What can I do utilize the Leviton Voice/Data module which is Cat5e with the structure cabling that is installed and terminated as 568B? Can I use an external crossover patch cable or could I would I need to make up or buy specific patch cords to convert from 568A to 568B? I sure don't want to have to reterminate 44 jack terminations.
Will RJ11 telephone work through all of this confusion?
Thanks for your help.
 Answer by Dmitri Abaimov posted 25 Mar 2004
Dear Peter,

Although it does get confusing, it won't really matter whether itís T568A or T568B as long as it is THE SAME pinout on BOTH ends. The laptop will run perfectly on both. I feel your pain about re-termination of 44 jacks (I assume, you meant to say 22 jacks and 22 patch panel ports), however, if you used T568B on the panel and T568A on the jacks, you HAVE TO go back and re-terminate either panel or jacks. It might be much easier to re-terminate the panel, unless you cannot easily access behind it, so I would start with the panel and check if it has color code inserts for both pin layouts. Leviton CAT5 or GigaMax panels can be used for both A and B.

Ethernet crossover cord actually converts T568A into T568B, but you do not really want to get into this, it will be a total nightmare to manage this system. The user will surely add some straight-through cables into the mix without knowing, and you will end up chasing problems all the time.

Analog phone would work in any combination of layouts, right or wrong, because pair #1 (blue) is at the same place in both.

Dmitri Abaimov, RCDD

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