sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring Reasons for 568B

There is a discussion going on here:
https://community.spiceworks.com/topic/222086-568a-or-568b?page=6#entry-1367213
about when to use 568A or 568B wiring configurations.

I vaguley remember a story that A was introduced first by ATT, Bell, IBM? One of the big players. They seemed to have some control of the wiring spec. So, when somone else wanted to use the same configuration, but 'big company' wouldn't let them, they just swapped pair two and three and called it B. and the rest is history, as they say.

I wish I could remember the source of this story, or maybe I'm dreaming it. Does anyone else remember anything like this?

Thanks.
Jim

My understanding is the the "B" configuration was actually Western Electric's configuration that Bell had been using before the "standards" were created - after the committee decided "let's do it this way" (568), they had to backtrack and call their wiring 568A, and incorporate everything already done by WE as 568B

The wiring scheme was developed by Western Electric back in the early 1970's to support the MET (Modular Electronic Telephone) sets on the Dimension PBX. It had no 'RJ' designation, as it wasn't a network jack.

IBM was never in the picture.

568A wiring was more of a continuation of the RJ11, 14 and 25 mindset, where pairs radiate out from the center two pins.

There was the problem: 568A made more sense since it kept in line with an existing standard. On the other hand, by this time, Western Electric systems had now migrated to the Horizon PBX and the Merlin key systems. With that said, there were likely millions and millions of "568B" jacks out there, so there was no way that they were going to fade into the sunset. In the US, it was decided to just allow both standards to coexist.

The WECO wiring standard soon adapted to the misnomer of "258A" wiring. This originated somewhere by a person referring to a 258A adapter, which was largely popular in areas where AT&T or Bell companies had a presence. The 258A was just an adapter that converted a 25 pair cable into six 8P8C jacks wired with the WECO (568B) pattern.

This is also why you don't see 568B wiring as much in Canada. Western Electric/AT&T didn't have as much of a presence there, so it never really took off.

EDIT: Jim beat me to it

This made me laugh:
"the standard for cabling is 568B and use CAT6, if you're not using at least CAT6 with 568b, your essentially limiting your network to a 5 year old standard."

As always, Ed is a font of information on "RJ 45" and wiring.... :rofl:

In 1995 I was working with a guy who set on the BICSI standards committee....the "fur-in-ers" all wanted BICSI to set "A" as the standard as their then two pair telephone sets would work without rewiring. That was when they wanted to do away with all standard rack deminsions and do metric. Neither happened back then.

:thumb: :thumb: :thumb:

Ed gets my vote as well.

It's amazing how those millennium generation geeks don't know history. They all think nothing existed before their sacred computers and ethernet so obviously 568A and B has to come from some IT standard.

It's also amazing how there is so much mis-information on the internet. Ed provided a through explanation. Maybe he should make it an informational sticky so Google will pick it up and those half wits can find it and learn something.

-Hal

They'd only believe it if he signed it as an IT expert....something not likely to happen :rofl:

How about Ed the IT Consultant?

-Hal

"You can't believe everything you read on the internet." Abraham Lincoln

I'm guilty of being an IT guy, Ed can ghostwrite under my name, haha

For what its worth I use 568A.

And, for those who don't know.

"A is a crossover and B is a straight-through"

But all my switches are Auto-MDIX so its better to have crossovers for when I need them and let the switches make them work as a straight-though.

Crossover? Straight-through? Those terms only come when you wire one end "A" and the other "B" last time I checked. Electrons don't care what color wire they travel on, as long as they are in pairs. The only difference to the guys with sight is when you cut the cable and try to terminate it on a block.

I happen to use "B" because the patch panels I buy are natively "B". That's where you terninate blue, orange, green and brown. You want "A"? Just terminate blue, green, orange and brown. Yeah, I'll get right on that. Since I'm a Leviton house, I've terminated for years as Blue, Green, orange to the right and brown to the left, keeping the white-color to the right for the first 3 and color-white on the left for the first 3. I can do that in my sleep (or is that hung over?)

The only problem is when you terminate voice jacks in 8-pin "B" and cut the cable down on 66 or 110 (or bix, eh?). Now the 2-pair voice line is blue-green instead of blue-orange. That usually only happens when someone else does the infrastructure, or the architect specifies 8-pin jacks in the scope, since if I'm doing the terminating, I'll use 6-pin voice grade jacks and terminate only the first two pairs, or two pairs per jack.

Carl

The only problem is when you terminate voice jacks in 8-pin "B" and cut the cable down on 66 or 110 (or bix, eh?). Now the 2-pair voice line is blue-green instead of blue-orange.

For those of us who are old AT&T guys we're used to that, especially when installing a Partner that uses two pair. You'll frequenty see it in old business that started out with a Merlin or Definity. Like Ed said, that's where 568B was born. You'll save yourself a lot of trouble by pulling a jack off the wall and looking at it before jumpering all other ends. Better yet, replace the jacks.

-Hal

"A is a crossover and B is a straight-through"

Is a quote from the post.

Thanks Ed. You never cease to amaze!

Around my house the saying (especially from my kids who have pulled a lot of wire and terminated it) is: "A is AWFUL and B is OKAY"

Canada uses the b standard. Not sure why but that was in all cases, 99 percent of the buildings. I remember once walking into a store, and doing a troubehoot call. One bad jack at terminal end. Repaired. Tested, no go mm looked at other end, it was wired 568a standard.

Make a correction, Canada uses 568A standard.

An ethernet "cross-over" cable has no designation, it is what it is. The w/o & w/g prs are swapped on one end. An A cable or a B cable can both be "straight thru" if they are the same on both ends.

Canadians use eh! Americans use 568 B

Google Seach ISDN wiring standard

Their is no differance in the A or B standard they both use the same pin outs. If you where colour blind their would be no difference. If you use A on one end and B on the other you have a cross over cable... for a straight cable you need both ends the same eithe A or B...

:bow:

A makes the most sense in respects to 2 pair voice. (pin 4-5 and 3-6)

B makes the most sense in respect to T1. (pin 4-5 and 1-2)

In both of the above cases whiteblue, and whiteorange are going to be the pairs in use.

Neither a or b make sense for 10/100 Ethernet. As this type of communication uses (a) second and third or (b) third and second pair for RX and TX respectively.

RJ31X and alarm CPE make me go insane.

Regardless of chosen pin out (a or b), ring should always be on the right when working horizontally and tip should always be on the top when working vertically. Pairs should never be split when the option to maintain the pair is possible - Even for short distances.

RJ31X is easy. T/R in on 4,5; T/R out on 1,9.

Really. I don't know what the problem is except that you don't understand how they are supposed to work.

It's like Jeff says and when the plug is inserted the CO line is looped through the alarm panel then back out to the premises. If the plug is removed there are jumper bars that are part of the jack that connect the CO line directly to the premises to maintain service.

You can plug a regular line cord with a phone or butt set into the jack and get dial tone since the CO line is on the usual pins 4&5. This is one way to test.

When the alarm panel goes into alarm it disconnects the premises wiring and connects to the CO line to dial out. When that happens any call in progress will be disconnected and the line will go dead. This is another piece of information to keep in mind if troubleshooting a dead line. If you have DT at the jack but the phones are dead suspect that the dialer may be hung up. Pulling the plug out of the jack putting it in bypass will confirm.

Also, since the RJ31x is an 8 pin jack and the pre-made alarm cords are 8 conductor some alarm installers will jumper two of the unused pins on the jack and connect the corresponding wires from the line cord to a tamper zone on the panel. This will give an immediate indication to the panel that the plug has been removed and depending on how it's set up may just indicate a trouble or cause the panel to go into alarm. So keep that in mind before pulling the plug. You don't want the cops showing up.

-Hal

568A and 568B
10/100Base-T uses only the orange and green pairs
the telephone uses the blue pair
the brown pair is used for POE
:rofl:

Unless there's a difference between Canadian and American POE standards, we don't have one that provides voice anywhere. POE positive is bonded on the white/blue pair and POE negative is bonded on the white/brown pair.

LOLOLOLOLOL

Ok, then if you understand all that I said explain why you still have a problem.

-Hal

splitting pairs, and ring is on the left on the boards.

Huh? How are the pairs split.

You sound like a sparky. There are all different manufacturers of jacks and I have used many different RJ-31x's over the years. I never noticed or cared how the terminals are arranged. I just wire them as they are supposed to be wired. Most will have the diagram in the cover.

-Hal

Not sure what you are referring to there. As Hal said, and as I have always done, just wire it up as the jack or equipment specifies. Usually diagramed out for you. Never have had a problem.

Pin 1 and 6 is only a valid pair in RJ61. And to my knowledge no one uses RJ61.

Thus its either the pin out on the line cord is:
A) Not a Standard
B) Splitting pairs

Either or is fine with me.
Regardless, the inconsistencies from general telco practices require extra care when modifying the installation. This "make me go insane" as most alarms are either wired in poorly with no jack or -more commonly- as a set.

Here we run our ADSL/VDSL2 line though the alarm system before it goes into a potsplitter. This means the integrity of the alarm installation is very important to ensure a quality installations.

And, Almost every job I work on requires disconnecting the alarm from OE at one point in time. Either for tests, verification, or adding highspeed equipment. I am aware of two times when Police arrived at a job site for a number I was working on - and it was because of an OSW trouble (s/c) on a fax line that rang though to 911. However the Idea of a temper switch being wired into the line seems smart, I know of one job where a fake nid was installed with a tamper line running though it. The idea was If the line was cut it would be very obvious that someone was trying to disable the alarm as the OSW didn't actually go anywhere but inside.

You dont have any issues running your ADSL/VDSL thru an alarm panel and putting the filter/splitter behind it? I always try to avoid putting any form of DSL on alarm lines...and if I do, try to put the filter ahead of the panel. If I try to go behind the panel, I have seen some of their equipment affect train rates on the modems.

Company policy to install the potsplitter AFTER any alarm/CPE designed to seize the line.

If the ptsp is before the alarm system then any s/c in the ptsp/modem/bonds or on/in the isw/jack could cause the alarm to not properly function in an emergency situation.

I'm not sure that I understand you on this. An RJ61 is a four-line jack, with line 1 being on pins 4/5, line 2 on pins 3/6, line 3 on pins 2/7 and line 4 on pins 1/8.

I think he is talking about the pinout on USOC jacks. With an RJ61 jack, pin 1 is tip and pin 8 is ring? (dunno, I didn't look) and he considers only those pins to be a "valid pair" because tip is on the left somewhere?

Could it be that he thinks the pairs are split because the only T&R that is on adjacent pins is 4&5?

-Hal

Well, if the alarm dialer doesn't hang anything on the line while it is inactive- IE there is just a DPDT relay that transfers the line, then there should be no problem with DSL. Thing is that most monitor the line for ringing and loss of battery so that is going to disrupt DSL the same as a phone without a filter.

I don't know if this has been changed with security panel manufacturers now including a DSL filter in the panel but I wouldn't want to take the chance and use a DSL line for security.

-Hal

woops, sorry I Meant pin 1 and 8 not 1 and 6.

Quote
RJ31X is easy. T/R in on 4,5; T/R out on 1,9.

--------------------
Jeff Moss

I think that is correct for alarm jacks

I have always used 568A. I see some people using 568B. it does not make any difference technically.

568A & 568B pins 4/5
the blue pair is used for telephone:
brown pair pin 7/8 is not used.
except POE uses brown pair 568A & 568B

10/100Base-T systems

I am going out to beat my dead horse...

I must have been asleep, I meant pins 1 and 8 lol

I wondered where pin 9 was located in an 8 pin jack.

Welcome to Monday part 3.

Uhhhh, I believe the 8 PIN "RJ31/45/et al, plug and jack is actually capable of 10 pins. Or should I say was 'designed' as 10 pin capable.

RJ50 according to wikipedia, never seen them in person tho.

I've seen 10 pin modular plug connections on APC battery backups.

Here's one for the polarity freaks...

"RJ50". Now that is funny! Thanks, Andy for the chuckle. I wonder how long it will be before the CG's come up with an RJ55 (maybe their version of a gigabit network connection?)

Let's remember that much of what is on Wiki is there by 'professionals' who have no clue of what they are speaking. There is little to no proof made as to the legitimacy of much of the information there. Thank goodness that the popularity of the site has summoned feedback from other posters who can debunk (or verify) information that is provided.

Yes, there is a ten-position version of an 8P8C plug/jack. They are quite common in some POS (cash register) systems between the keyboard and the base system. The only ones that I've encountered are what appears to be a 10/C short handset cord.

Ed,

I'm no expert exactly, but isn't the RJ45 is the correct term for 1 1gig speed, and that RJ50 will be for the new cat6-7 10 gig?

:bang: :bang:

-Hal

:rofl: :rofl:

:rofl: :rofl: :rofl:

:rofl: Batten down the hatches
:rofl: :read:

I read it on Phone System Tech Talk, so it must be true

Cepega, please don't tease the old folks!

Please tell me he is joking, or what little faith I have in humanity will be gone!

Lightninghorse,

I appologize for a bad joke, it is just that I've recently encountered a few phone calls to the internet and phone service provider and the term RJ45 was thrown around alot loosely.

Didn't mean to raise people blood pressure with bad humor.

and I was getting ready for a ring side seat for this.

Yoda: :rofl: :rofl:

Me too IPK. I would love to watch some of these guys extend 5 T circuits over 25 pair. Lol. "Gold, copper, purple...? What do I do? The box only show 4 colors?" This has been a fun read, thanks for the laughs guys. And thanks for the info Ed.

Let's all try to remember that "RJ" stands for "Registered Jack", not any kind of plug, cord or module. It is just an organized and uniform set of wiring schematics to make the same model of jacks (actually, they are technically connecting blocks) do many different things.

Oh, and the registered jack program came out decades before the IT industry was even weaned from the bottle.

There never was an RJ50. I rest my case, Your Honor.

A slight aside, IT stands for Idiot in Training.....

CG stands for Computer Geek.....

...and Friday is their parade day....

Finally, even if Al Gore said he invented the internet, it is the telephone industry that invented the circuitry to even have it thought of. Artificial insemination at it's worst.

:scratch:

"B" is the best...bet ch'ya!

T568B wiring scheme (also referred to as AT&T 258A)
T568A is default, T568B is optional. :toast:

IBDN/CDT Certified for What's Comming Next! :thumb:
https://www.contact-directconnect.com/news.htm


https://www.google.ca/#hl=en&su...df05399aa13f3727&biw=819&bih=350

T568A is default, T568B is optional.

You can find as many opinions on this as there are people willing to ofer them. We know the origins of 568B. My opinion is that A was implemented in the days when combo data/voice wiring was punched down on 66 cross connect blocks in order to maintain the pair 1/pair 2 order on the block. Since everything is now on patch panels it makes no difference. Pick a standard and stick to it. B is most common in this country.

-Hal

Not every one uses patch panels! I prefer using bix based network design, this method is more cost effective and gives you a plethora of configeration options. Patch panels usually become a shoddy mesh after being worked on by IT programmers. When I do work on patch panels I make my own patch cords and cut them to the perfect lenght this is more aesthetically pleasing then having 75 patch cords that are 5 feet too long. :rolleyes:

Most people in Canada use T568A but not all. "eh"

IBDN/CDT Certified for What's Comming Next!
https://www.contact-directconnect.com/news.htm

Not every one uses patch panels! I prefer using bix based network design... Most people in Canada use T568A.

I think you answered the question of why 568A is popular in Canada. If you use other than patch panels A makes sense.

-Hal