+1

Let's look at this.


Let me describe it differently, as I find this hard to imagine. Think of the four keys of a cursor pad and rotate clockwise. Ignore the possible mixup as it won't matter. You've got top, right, bottom, left. Lay his description of the wires over this and you've got
12:00 = top = green
3:00 = right = brown
6:00 = bottom = blue
9:00 = left = orange

Okay. Fine. Wonderful. This arrangement, for some reason, is easy to spread to the proper arrangement for 568A. Why that would be, since you have to split the orange to both sides of the blue, I can't see. More importantly, at the other end of the wire, the pairs come out in a mirror image of the above. If you hold the wire so top and bottom are the same, this is what you have:
12:00 = top = green
3:00 = right = orange
6:00 = bottom = blue
9:00 = left = brown

If the other arrangement is advantageous for A, doesn't the reversal of order at the other end argue that perhaps the other end is more easily wired with B? I'm not at all sure, but think about it. Maybe make up another cable, Audiophiliac, and see if it's not just as easy and not easy at the two ends with B.

There is a real simple way to identify "A" versus "B"

Hold the connector straight up with the cable towards the bottom and the tab away from you. Position one is now the the left, eight is to the right.

Whether "A" or "B", the BLUE pair is always in the middle and BROWN is always to the right. Neither pair is used for data.

The means that ORANGE and GREEN are the only two pairs used to transmit and receive.

With 568A (phone standard), we start with the GREEN pair and straddle the blue with the ORANGE.

With 568B (data standard), we start with the ORANGE and straddle the blue with the GREEN.

We only use ORANGE and GREEN, so it doesn't really matter as long as both ends are the same configuration.

Once I saw THE PATTERN, I threw away the "cheat sheet" I had tucked away in the wallet. I hope this helps.

Howard Kohnstamm

vithoward,
you are totally correct. However, once I saw the pattern, then didn't do any punchdowns for a month, I had to be reminded by looking at the cheat sheet to see where orange and green go.

Also, your description doesn't cover the various times I've had IT guys be dumfounded that I even considered using B. For anything. Last time I ran into this, I mentioned B, there was silence (this was on the phone), and he didn't really get back into gear talking until I said, "of course, when I go to an existing site, I check what is used and duplicate that for consistency."

How does "doing punchdowns" mean putting 8P8C male connectors directly onto cat6 wire?

Going back through the "cat6 twist" debate, it's clear that you guys are talking about those two different termination methods. Wire that is well ordered to punch down onto a keystone jack is not well ordered for a male crimp connector.

I don't have a source for this, but I thought that you can't have a standards-compliant cat6 installation without using female punchdown connectors (or equivalent) at both ends of the wire. I have yet to see a commercial job where male connectors were used for structured catX cabling. It's jacks / panels and patch cords all the way.

Also, if you're carrying around a cheat sheet for identifying catX terminations, you're either working with a number of wiring standards exceeding those mentioned in this thread, or you do 2-3 terminations per month.

What do you mean about only using ORANGE and GREEN?

I'm ASSuming he means that typically ur only using the orange and green pairs, pins 1,2,3 & 6 in a standard network connection.

Who really uses POE or Gigabit, it is just another passing fad like HDMI...

That was the point I was trying to make - I was too subtle.

I terminate based upon purpose. Data is T568B and telephone is T568A. This way whether its a cable or a jack, a simple look will identify its purpose and not require toning or a trip back to the head end. Additionally T568A will provide the correct pin out for either a KSU/PBX system or a simple 2 line install. As well as providing plug and play change over from SLT to system phones

Funny. On the few commercial jobs I've done, I've suggested to the IT guy that I would wire A, and they seem to get very flustered. I shrug my shoulders and tell them i will wire it B - it seems to make them feel better and, well, I like making people feel better.

Personally I like to wire A in residential - it makes it easier to go from data jack to phone jack if I need to.

One thing I've always wondered: I thought it was a big deal to keep the twisted pairs twisted until just before they go into the RJ45 connector - keep it as tight as possible right?

So how come all the Sonos systems come with a flat network cable that clearly does not maintain the twisted state of the cable for four five feet or whatever it is....

+1, they lay better into the keystone jacks (we use PDL) going B spec.

Side note:

A while ago we had an issue using a cheap HDMI extender over Cat5e (customer suipplied), the picture would drop intermittently in a clients Bedroom and the run was only 10 meters (32.8 feet in the old language) from the HDMI Matrix. The cable spec was A, so first we changed the connectors on both ends to make sure it was not a faulty plug, we then run the HDMI extender directly into the source, bypassing the Matrix, but....the issue was still present and we where lucky enough that it was visible pretty well much straight away. At the time we had a specialized data guy working side by side on another project and he mentioned to us to go B spec, so for "sh#ts and giggles" we did. We waited around 3/4 of an hour and had no dropouts so we put the job under observation with the intent of returning with a new extender. I called the client back the following day to discuss prices and a return date and they said that they had not had a dropout yet......so I called a week later and they had not had a drop out at all, they where very pleased we had fixed their issue without the need of purchasing a higher spec extender.

Now it could of been 3rd time lucky on the termination of the plugs, but the IT guy did mention that the twists had alot to do with them going B spec as there was less interference inducted into the pairs giving more stability...or something like that :) All I know is that I have been going Cat6 B spec since then for all DATA and we have had no problems yet, touch wood.

A for wall and panel terminations. B for patch cables.

Lots of reasons to do it one way or the other in different circumstances based partially on the people you're working with and what their preferences are. No hard and fast rules that hold any water technically.

Even I.H.S.'s solution probably depends on using the same brand and model of wire that was on that job, which was customer supplied wire. If that one worked better because of the twist rates of the different pairs, it was luck -- there's no spec saying which pair has to have which kind of twist rate, only that they all have to be different to meet a crosstalk spec. I do a lot of retro work, as well as working with a guy who is okay with not sticking with one brand and model, and I see they are not all the same.