568 A or B

[mdshunk]

I still get confused, and I think I need a little bit more information to set these termination methods solidly in my head. When terminating an 8 position jack for data, which termination sequence do you use 568A or 568B? Why? Which is for which?

When terminating an 8 position jack for 4 voice lines, which do you use; 568A or B?

In times past, you only had to worry about WECO and USOC termination methods. Now we have this 568A and B business, and I'm all mixed up.

Thanks for 'splaining.

[Jacksnap]

When terminating an 8 position jack for data, which termination sequence do you use 568A or 568B? Why? Which is for which?
568A is 'straight through'. 568B is 'cross-over'. For data connections directly between computers and directly between hubs, BUT not between hub and computer (printer, whatever) use 568B 'cross-over. There is an exception on the hub to hub (router to router).. which is if the hubs have an 'uplink port' then use a 'straight through' 568A. To confuse you even further; 568B 'cross-over' has 568B config on one end and 586A config on the other!!
Most data installs are 568A 'straight through' and go from computer, printer, etc. to a router, hub, etc. So, for data it can be either, but usually 568A.
When terminating an 8 position jack for 4 voice lines, which do you use; 568A or B?
For voice it also can be either A or B, depending on what the manufacturer says works with their KSU/PABX/PBX/DID equipment.
Good luck with doing a job with this stuff because it really plays havoc to your productivity level. In my later years, my close-up vision went out, so reading glasses and a magnifying glass was a necessity because the equipment instructions and diagrams usually are written in ridiculously small font.

[suemarkp]

If this is premises wiring, then it doesn't matter for data as long as you pick a standard and go with it. My wall jacks have color codes for both, and I picked 586B. Later, I bought a punchdown block, but it was only color coded for 586A. Since I wired the jacks as B, I had to violate the color coding on the punchdown block. I know this, but some other poor soul who inherits this will be confused. I should really redo the walls to 586A and then match the colors on the punch down block.

Supposedly 586B is "commercial" and 586A is "residential". So if the color coding on equipment is for only one choice, it will depend on who that item is marked to as to which choice they gave you. I think the intent of A was to make it easier to mix voice and data on the same jack. But I would avoid that approach and use different cables and jacks for phones and data.

I think the most important point is not to crossover the wires in the walls, as that is not generally done. Use a crossover patch cable if crossing needs to be done.

[bmwpower]

568A is 'straight through'. 568B is 'cross-over'. For data connections directly between computers and directly between hubs, BUT not between hub and computer (printer, whatever) use 568B 'cross-over. There is an exception on the hub to hub (router to router).. which is if the hubs have an 'uplink port' then use a 'straight through' 568A. To confuse you even further; 568B 'cross-over' has 568B config on one end and 586A config on the other!!
Most data installs are 568A 'straight through' and go from computer, printer, etc. to a router, hub, etc. So, for data it can be either, but usually 568A.

Jacksnap,
568A vs. 568B has to do with the ordering of the wiring at the jack. A cable can be wired for 568B and not be a crossover cable. A "crossover cable" contains wires that are crossed over from one end of the run to other end as seen below. The crossover patterm will vary depending on which standard (568A or 568B) you use.

I agree with everyone to pick one stadard and go with it for the whole project. It also helps to pick a common manufacturer whose standard is used throughout their jacks, punchdown block, etc.

[mdshunk]

My wall jacks have color codes for both, and I picked 586B. Later, I bought a punchdown block, but it was only color coded for 586A. Since I wired the jacks as B, I had to violate the color coding on the punchdown block. I know this, but some other poor soul who inherits this will be confused. I should really redo the walls to 586A and then match the colors on the punch down block.
This is sort of the same situation that prompted my question. I finished a job that was done with customer supplied materials ( :mad: ), and it was a real "treat". At the jacks I picked 568B, as is my usual custom. At the Leviton "command center", the color coding was only for 568A. Like Mark, I had to violate the color coding at the punchdown or redo every single jack. I opted to violate the color coding at the punchdown because time was of the essence. I know that it will function, but it rattled me for a while. I hadn't heard the 'A' for residential and 'B' for commercial. I did notice that most or all of my pre made patch cables were wired in the 568B configuration. I accidentally made a patch cable in the old voice type USOC configuration some time ago and it did work; albeit quite slowly.

[Jacksnap]

Remember when you wire these to the standard, only pins 1, 2, 3 and 6 are used for data transfer. So, yes, in many installations for data it will work either way. In telecom, we had to do it by the book. Another tech could come behind me, like 'suemarkp' mentioned, and be totally at a loss because I did it my way and not to the TIA standard.
Another major difference in A & B is Backward Compatibility. If using the A, you have BC to one and two pair USOC wiring; but if using B it only gives one pair BC. Granted the B is/was most popular for commercial installs but any government work I did was spec's to the A standard. Like I said, it's really confusing when you have to work to spec., but like you all point out, you can wire it anyway, any combo of colors, as long as in the end it works.