# Sticky  T568A or B



## daveEM

So...









When I buy a cable at the local store with ends on it how are they wired?

I have to make up my own cable.


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## dave91

It will say right on the cable we always use A in Canada he


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## jza

Look through the clear plastic connector and see for yourself.


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## drsparky

Both will work, both are accepted standards. Some customers will specify one or the other. You should use the same for the permanent wiring as the patch wiring to avoid a little noise at the transition.


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## daveEM

T568eh? 

I guess it doesn't really matter but got my magnifier out, looks like B. 

Appears B is what most use now, so that's what I'll do. Gotta go with the flo.


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## The_Modifier

FYI:
A Crossover cable is made by doing one end in T568A and the opposing end T568B. (Sometimes used when interconnecting routers etc- at least that's what I found on youtube a few years back).

Most commonly in Canada it is wired with T568A as mentioned before, if you purchase pre-made patch cables they will most likely be wired as T568B.


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## Rollie73

All we use is A. Never use the B config unless we are purposefully creating a crossover cable.


Remember when you are looking at the male connector and trying to determine if it is A or B....or when you are terminating a male the locking clip should be on the bottom of the connector.


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## 480sparky

If you're making simple patch cables, does it really make a difference?


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## daveEM

Na it doesn't matter. I'm in Canada so I guess I should use A. 

The two cables I bought are B tho. I guess we don't make anything in Canada anymore.


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## Rollie73

480sparky said:


> If you're making simple patch cables, does it really make a difference?


 
No it doesn't, with one minor exception. 

You MIGHT get a little noise at the transition point using a B patch cable in a system that is exclusively A. I've been told that this noise MIGHT slow down data transmission. 

I personally don't believe it, but its what we were taught and what I've been told by some IT guys.


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## daveEM

The patch cable that came with my 8 port (4 POE) switch has 'Made in China'. It's a B.

So Rollie I'm thinking if you made up 20 drops on a job, then the customer needed a 10 foot patch cord a year later and picked one up in Best Buy or somewhere he would get a B and plug it into your A system. And never know.


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## Rollie73

That's exactly why I personally don't believe the rhetoric, Dave. 

I've worked on too any systems that were in for a year or two......added cables into racks.....pulled new drops for systems and have seen numerous incidents of B cables right beside A cables.....homemade cables with the twisting of the pairs open for two inches before it went into the RJ45 jack.... cables that were tied into knots with the cable kinked and twisted into something that resembled a licorice twist gone wrong......and the entire system always worked just fine.


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## 480sparky




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## chewy

Theres a slightly different twist rate between Green and Orange but I think once you also take into account other causes of impedance the fact the orange has a looser twist is a non issue.


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## drsparky

There is a little more that just the color of the insulation involved here. The twist rate of the conductors should remain constant. If data is running pins 1+2 (green) on a permanent A cable (jack is made as a A) it would have a twist rate of 65 turns per meter. Then if a B type patch cord is used 1+2 (orange) it would go down to 56 turns per meter. The impedance change would be detectable at high speed and makes noise and cross talk on the wire, noise on the wire puts errors in the data, the Error Correction and Detection software starts cleaning up the data, this slows it down.
The same type thing happens when a connector is made poorly, by untwisting the cables to make it "look better" you are killin' the data flow. 
The speeds the cable pass 0s and 1s make every part of the cable an antenna, its not just about continuity it also radio frequency engineering.


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## dave91

Hey 480sprky where did the photos come It needs a little wire combing


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## 480sparky

dave91 said:


> Hey 480sprky where did the photos come It needs a little wire combing


As you wish.


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## Rollie73

drsparky said:


> There is a little more that just the color of the insulation involved here. The twist rate of the conductors should remain constant. If data is running pins 1+2 (green) on a permanent A cable (jack is made as a A) it would have a twist rate of 65 turns per meter. Then if a B type patch cord is used 1+2 (orange) it would go down to 56 turns per meter. The impedance change would be detectable at high speed and makes noise and cross talk on the wire, noise on the wire puts errors in the data, the Error Correction and Detection software starts cleaning up the data, this slows it down.
> The same type thing happens when a connector is made poorly, by untwisting the cables to make it "look better" you are killin' the data flow.
> The speeds the cable pass 0s and 1s make every part of the cable an antenna, its not just about continuity it also radio frequency engineering.


Excellent info Doc.


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## daveEM

drsparky said:


> If data is running pins 1+2 (green) on a permanent A cable (jack is made as a A) it would have a twist rate of 65 turns per meter. Then if a B type patch cord is used 1+2 (orange) it would go down to 56 turns per meter.


^^ :thumbsup:

The things a guy learns here.  Individual pairs in the cable at different twist rates. *Great info*. I hit the web and found this...










Quite the thing. I guess I'll do B to keep things the same.


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## Holt

At the end of the day the data still always passes over pins 4 and 5m which are the same weather you go a or b. So you can mix systems together. However if wiring a poe system you need to use the same throughout


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## guest

Great info in here so this is now a stuck thread. :thumbup:


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## GrayHair

*A pair is a pair is a pair ... NOT!*

Started having new installs that would drop off-line occasionally, except if cameras were being watched, and then they would drop about every day. The longer the run, the worse the problem. Turned out the installation manager said it didn't matter which pairs installers used as long they were the same on both ends. 

Reterminating correctly always fixed the problem. I had trouble remembering the correct order for a plug until someone gave me the memory aid "Ollie's ORANGE gal BLEW bad GREENS burned BROWN". Ok, the spelling for Blue is weird, but it worked for me.

Hey 480, I didn't know you were on that job too! Places like that always made me very nervous (and careful). :laughing:


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## drsparky

Holt said:


> At the end of the day the data still always passes over pins 4 and 5m which are the same weather you go a or b. So you can mix systems together. However if wiring a poe system you need to use the same throughout


No you will not pass qualification testing, only verification and certification. Mixing cable types will slow down the network, a Fluke Cable IQ or similar will spot it. You may get the end item to work, but will not work well. I guess you can always blame a slow server or router, but the problem is often crappy cabling. Verification and certification testers only tell continuity and sometimes distance, not cable performance. :thumbsup:


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## McClary’s Electrical

Rollie73 said:


> No it doesn't, with one minor exception.
> 
> You MIGHT get a little noise at the transition point using a B patch cable in a system that is exclusively A. I've been told that this noise MIGHT slow down data transmission.
> 
> I personally don't believe it, but its what we were taught and what I've been told by some IT guys.


Oh come on. If it's "b" on both ends, are you trying to tell me the electricity knows the wires have changed colors?


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## Holt

drsparky said:


> No you will not pass qualification testing, only verification and certification. Mixing cable types will slow down the network, a Fluke Cable IQ or similar will spot it. You may get the end item to work, but will not work well. I guess you can always blame a slow server or router, but the problem is often crappy cabling. Verification and certification testers only tell continuity and sometimes distance, not cable performance. :thumbsup:


I didn't know that. Thanks for the lesson.


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## sarness

mcclary's electrical said:


> Oh come on. If it's "b" on both ends, are you trying to tell me the electricity knows the wires have changed colors?


No, it doesn't know color, but it does know twist (if your mixing A and B in the same run).


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## The_Modifier

mcclary's electrical said:


> Oh come on. If it's "b" on both ends, are you trying to tell me the electricity knows the wires have changed colors?


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## Rollie73

mcclary's electrical said:


> Oh come on. If it's "b" on both ends, are you trying to tell me the electricity knows the wires have changed colors?





sarness said:


> No, it doesn't know color, but it does know twist (if your mixing A and B in the same run).


Sarness beat me to it mcclary. Apparently the change in the twist rate if you change from building wiring that is done in A to a patch cable that is done in B will cause data transmission errors. 

Read drsparky's post about it (post #15) ......he explained it well.

I still don't believe it all though. It still works fine even after the errors are cleaned up:laughing::laughing:


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## Ty Wrapp

chewy said:


> Theres a slightly different twist rate between Green and Orange but I think once you also take into account other causes of impedance the fact the orange has a looser twist is a non issue.


I was taught to use the green pair as the feeder from the demarc to the modem because of the tighter twist.


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## five.five-six

Rollie73 said:


> No it doesn't, with one minor exception.
> 
> *You MIGHT get a little noise at the transition point using a B patch cable in a system that is exclusively A. I've been told that this noise MIGHT slow down data transmission.
> *
> I personally don't believe it, but its what we were taught and what I've been told by some IT guys.



You might, but the likelihood is very small. Obstensively the variation between 568A and 568B is just insulation color and electrons don't care what color the insulation is (simply swapping GN for OR) but there is this one caveat that you eluded to: 

In order to minimize crosstalk across the pairs, each pare is twisted at a slightly different rate, 



Pair color [cm] per turn Turns per [m] 
Blue 1.38 72 
Green 1.53 65 
Orange 1.78 56 
Brown 1.94 52

on a 10/100 system, only pins 1,2 and 3,6 are used so in theory 568eh should give you slightly better noise rejection than 568b.


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## mgal

Sorry Holt,
pins 4 and 5, the blue pair are used primarily in telcom... and in gigabit networks. but in this case, its going to be pins 1, 2, 3, and 6, orange and green pairs.

As to what to do, if what you've got is 2 pair used for phone, use the other two for your network. Remember, try to use the green and orange pair for networking. the data transfer related to the info in Drsparky's post is accurate and necessary. You'll be limited in speed, but, unless you think you can get new wire there... give it a shot.


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## McClary’s Electrical

Rollie73 said:


> Sarness beat me to it mcclary. Apparently the change in the twist rate if you change from building wiring that is done in A to a patch cable that is done in B will cause data transmission errors.
> 
> Read drsparky's post about it (post #15) ......he explained it well.
> 
> I still don't believe it all though. It still works fine even after the errors are cleaned up:laughing::laughing:


I posted without reading everything. I never knew it would matter but U guys it makes sense when you really think about it.


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## crazyboy

I do everything in B.


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## Kaffeene

When I started out I used "B". Then I switched to "A" when I got my own company, then back to "B". 

I'm not even really sure why a switched back and forth.


edit: Now I know why I switched, most of the patch cables I am buying are T568 B.


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## B-Nabs

So I have a couple of questions (which may or may not be answerable):

Why don't we all agree on one standard and stick to it?

And a somewhat related question, mostly applicable to Canada,

If most premade patch cords are wired in 568B, and switching from premise wiring in 568A to said patch cords could introduce crosstalk and other problems, why do we wire in 568A?

I understand there's some history behind why different standards are used in the two countries (which I can't remember now), but why don't we all just agree to use one or the other on both sides of the border?


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## B-Nabs

Looking at what I just posted I guess I just asked the same question three different ways with way too many words. :bangin: DERP


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## Rollie73

When I first started doing any structured wiring, the industry standard in my area was to use the B configuration. All the patch cords were in B and the building wiring was B.

Not long after.......we started getting all our patch cords coming in as A configuration and we switched over. All the cabling guys in the area were now doing A and are still doing A. 
I have noticed that a lot of the patch cables are now coming in as B again. Damn you China Looks like its time to change back.


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## drewsserviceco

Question:

Is it true that more twist per inch means faster data transfer? Or is it the relation of the twists from pair to pair?

If the higher twist rate, then according to the info provided above we should be using brown.....

With no facts to back it up, I am inclined to think it is the relationship of the pairs to each other with their respective twist rates.


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## telsa

Since Pin 8 is always BROWN, orientation should never be a problem.

Easy, peasy.

Color code 'cheats' are everywhere to hand.

It's the rat's nest tendency that makes things 'interesting.'


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## JW Splicer

drewsserviceco said:


> Question:
> 
> Is it true that more twist per inch means faster data transfer? Or is it the relation of the twists from pair to pair?
> 
> If the higher twist rate, then according to the info provided above we should be using brown.....
> 
> With no facts to back it up, I am inclined to think it is the relationship of the pairs to each other with their respective twist rates.


A tighter twist means a longer electrical length than actual jacket length, meaning tighter twist rate has a higher impedance. You can see this in the delay skew readings. When you think about how this is measured (the nominal velocity of propagation) speed of light in a vacuum vs. speed of media (copper, fiber, coax) it makes sense that the longest electrical length is usually the slowest pair.
The main purpose of the twist rate is to provide a capacitive coupling in the pairs balancing the media, the main purpose for different twist rates is to prevent crosstalk/noise between adjacent pairs. In the old POTS days this wasn't as big of a concern, but at higher frequencies it becomes the big issue.


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## splatz

@drsparky - 

I read your reply regarding mixing 568A and 568B with interest. With all due respect, I am really skeptical that there's enough of a difference in the impedance between the green pair and the orange pair to have any real difference with data transmissions. 

Have you ever actually measured this with your own eyes? I have certified tons of cat5e over the years and it's never been an issue. 

One of the testers I have used came with test leads hardwired into a proprietery plug that screwed into the tester. They only gave you one pair of leads; if different leads were necessary for 568A and 568B pinout, they'd have needed to give you two. 

Thinking about it more, having bought thousands of patch cords over the years, never had anyone even offered whether to sell me 568A or 568B - if it was a big deal, you'd think people would look for it. LAN admin types are notoriously fussy about details that are of no practical importance. 

Regarding impedance, I would think that the length of the conductor is the main determinant. Different twist ratios are going to make the actual length of the conductors a little different in each pair. This skew is at times a problem on long runs with lousy cable. But by mixing a 568a link with 568b patch cords, you'd actually get less of a total difference in lenth between pairs, and more even impedance / delay skew pair to pair. Not that I think that's of any practical importance. (I am admittedly out on a limb with this, please by all means straighten me out if I am off base.) 

Anyways - thanks to pain in the axe VOIP systems I have done a LOT of low level network monitoring and etc. this past couple years. I have seen MANY problems caused by marginal patch cords, but not one by mismatched 568a/568b patch cords. So even if there is a measurable difference, I can say that in my experiece, it seems to be within the tolerances of the encoding etc., too small to cause bad packets.


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## vickieB

@480 Sparky
Definitely need some cable management in those pictures! What a mess.


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## Mack Fisher

The Cat-5 and its connector came out of the Bell Labs for the telephone network. I still have to give the Bell System installers and technicians’ top rating for the training they received & the materials they used, though most of that was due to the deep pockets of the monopoly we call the Bell System. Bell Labs for its research, Western electric for the manufacturing arm. The bad old days or the good old days when we as an electrician pulled wire, the Bell System installer would be there pulling station wire (4-conductor cable) for the wall jacks, if you are a union electrician you’d find that the Bell guys were often member of the same local. 
Wire color codes there are two color codes because “Bell System Practice” said for all telephone installations it would be done this way. For some unknown reason when the IT people adapted modular wiring they decided to come up with a different color code.
A buddy of mine asked me to come over and give him some ideas for his upcoming AT&T U-verse system. I was there when the installer arrived out of curiosity I asked him which of the two wiring color codes they use for their CAT-5, the reply either one as long as we use the same one in the building. The installer did not receive the same level of training as his compadres in the wire side of the business.


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## splatz

Mack Fisher said:


> Wire color codes there are two color codes because “Bell System Practice” said for all telephone installations it would be done this way. For some unknown reason when the IT people adapted modular wiring they decided to come up with a different color code.


The 568B pinout matched what Bell was doing and to this day matches T1 circuits which are still around after all these years and still done the same way. But with 568A, the blue and orange pairs match USOC jacks, so you could plug four conductor phone cable plug into an 8-conductor 568B jack and have everything match. 

Back then the AT&T phone systems used an eight conductor cord but others came out that used two pairs and the USOC wiring made everything match, but USOC was no good for networks, the pairs are not on the right pins, but 568A was good. Soon it didn't matter much because digital phones were just using the center pair which works with any of the three, so either A or B was fine.


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## five.five-six

Mack Fisher said:


> For some unknown reason when the IT people adapted modular wiring they decided to come up with a different color code.


It’s actually a known reason and it is logical.

First you have to understand how twisted pair defeats errors. Unlike coax where the there is basically a drained shield to protect against EMF, the tighter the twist on UTP the more likely the introduced noise will be the same on both conductors, thus canceling out the interference. 

Next you need to understand crosstalk, and that each of the pairs have a slightly different twist rate to avoid cross talk. 


Then you need to understand that on 10 base and 100 base, only pins 1,2,4&5 are used 

Orange has a higher twist rate than green so the IT people wanted the highest twist rate pairs.


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## 5kv flash

480sparky said:


>


I have seen this crap many times communication guys are slobs just like alarm installers, I worked communication 100 to 300 pair copper to single mode fiber ,my work is super organized otherwise u don't work with me,cat 5 and 6 is nothing to work with very basic comm.

Sent from my SM-A505U1 using Tapatalk


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## R777V

Rollie73 said:


> That's exactly why I personally don't believe the rhetoric, Dave.
> 
> I've worked on too any systems that were in for a year or two......added cables into racks.....pulled new drops for systems and have seen numerous incidents of B cables right beside A cables.....homemade cables with the twisting of the pairs open for two inches before it went into the RJ45 jack.... cables that were tied into knots with the cable kinked and twisted into something that resembled a licorice twist gone wrong......and the entire system always worked just fine.


All our Data center stuff is A, but every commercially made patch cable seems to be B. When we made runs from patch panels all A. All our Panduit patch cables supposedly certified Cat 6A, are B. However most patch cables aren’t as long as the patch panel runs. So I guess that would help. I’ve always been told wires don’t know what color they are! That sounds racist though.


Sent from my iPhone using Tapatalk


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## TheDrew

Long time (15+ yrs) IT Network Admin (and part-time datacom cabler) chiming in.

1) Never heard of any performance difference between T568A or B wiring, both work fine and meet the specs for cabling, so which you use really comes down to what is specified and/or used in the building. It doesn't really matter whether the cord is wired to A or B spec, they perform the same. And given a crossover cable (rarely used with modern kit) is an A to B cable, it really doesn't matter.

2) What matters more TBH is how good a job you do installing it, neat clean cable runs that are easy to follow years later, bend radius, leave some slack for later repair work, use the proper termination tools, these things make us datacom guys happy. Bonus points if your work get's upvoted on Reddit's Cableporn subreddit. 

3) CAT 6A is a cable performance standard, T568A/B is a pinout spec, so you can wire CAT6A either way.


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## kb1jb1

TheDrew said:


> Long time (15+ yrs) IT Network Admin (and part-time datacom cabler) chiming in.
> 
> 1) Never heard of any performance difference between T568A or B wiring, both work fine and meet the specs for cabling, so which you use really comes down to what is specified and/or used in the building. It doesn't really matter whether the cord is wired to A or B spec, they perform the same. And given a crossover cable (rarely used with modern kit) is an A to B cable, it really doesn't matter.
> 
> 2) What matters more TBH is how good a job you do installing it, neat clean cable runs that are easy to follow years later, bend radius, leave some slack for later repair work, use the proper termination tools, these things make us datacom guys happy. Bonus points if your work get's upvoted on Reddit's Cableporn subreddit.
> 
> 3) CAT 6A is a cable performance standard, T568A/B is a pinout spec, so you can wire CAT6A either way.


Old thread but very good advice.


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