atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring 568A vs. 568B

Hi guys, I just got a bunch of new 8p8c jacks for ethernet connections, that have the wiring digrams on them, but I'm not sure if I should wire it A or B. I've read a lot online about how to wire it A or B, but not sure why I should use one over the other. I'd just like to do whatever's more common so whoever has to go behind me won't have any trouble.
Thanks guys!

I'm not really sure that it matters just as long as you wire both the jack end and the plug end the same. Some will tell you that 568A is for residential and 568B is for commercial. The good thing about 568A is that you can generally use it for telephone as well.

There are DeFacto standards and DeJure standards. The first is by weight of the big boys using it and everyone else copying. The second is set by a governing body. TIA/EIA 586A and 586B are dejure standards. 586B is a clone of the older (don't ask me the number) Bell System standard, which was the defacto standard.

Just installed a new office, ran quad-four to each desk -- four four-pair cat-5e, jack panel in the terminal room to quad jacks under the desks. Red jack has the corporate 100baseT network, to the IP phone, daisy-chained to the computer. Blue will be going to a 10baseT DSL backup in case both D3s fail (yeah, right!) Green will be carrying a 9600 baud RS-232 connection. White is an analog line for modem/fax. Back the terminal room I have a cable with 8-pin modular plugs carrying the T1 from the demarq to the routers.

You might say that the 8-pin modular is the Jack of All Trades.

568A is the preferred method of the two. That said, as long as you do both ends the same and you are consistent in the overall installation, either method is acceptable.

I would only use B if there are already some terminations done in that style at this site.

Well, I have to have it the same way as the patch cables, right? How do I know how those are wired?

568A is the preferred method of the two? I am not so sure about that, at least not in the U.S. The popular 568B jack wiring standard in the U.S. was a simple association to the jack that looked like ATT/Western Electric's part number for 258 or 259 adapters.

Somewhere along the way, USOC and manufacturer's standards crossed paths. While, they were similar, yet not the same. I don't know if the U.S. USOC standards made their way to Canada, but the two separate standards between A and B still exist.

Since these adapters were so popular and commonplace, the term "258A" was frequently referred to as a wiring pattern 568B (take a look at an old supplier's catalog). While long-gone from production, these adapters hold their place in history as perhaps the most misunderstood part number. They ended up becoming a worldwide standard now known as 568B.

We are a worldwide support forum, so preferences vary between countries and continents. I suppose like many other posts on this subject, all that really matters is the fact that both ends of the cable are terminated using the same wiring standard.

Ed, thanks as always, you are a veritable encyclopedia of telcom information

What about the patch cables though? Do I need to make sure the jacks (at _both_ ends) are wired same as patch cables?

Here in Chicago I rarely see anything wired 568A

Chad, while I was busy correcting the typos in my original post I found that you had replied. I was too busy telling you how to build the watch instead of simply telling the time.

Here's the short answer that I should have given earlier: As long as the cable run between the outlet and patch panel are wired using the same standard (A or B), then you can use either 568A or 568B patch cords. The only restriction is that the patch cords must be the same type at both ends to function.

as long as its wired the same both ends a or b works fine for two pair telephone .

I thought the standard for structred cabling called for A . we dont do structred so I havent paid tht close attenion

Originally posted by Clinton: Careful here Clinton You are from Canada and just because 568A is the standard practice here doesn't mean it is everywhere.

I believe 568A is popular here because we tend to use the BIX format wall jacks and patch panels. With the BIX jacks, wire is always terminated in order, wh/bl, bl/wh, wh/or, or/wh, wh/gr, gr/wh, wh/br, & br/wh. (Another plus for using the BIX format, don't have to look at a silly little terminating picture, just punch in order, but that's another forum topic!). When you terminate a BIX wall jack or patch panel this way and crimp a RJ45 mod connector on the other end, if you use the 568A standard, the run will be straight through. If you crimp using the 568B, you will have a x-over run.

With keystone type jacks, you specifically wire according to the 568A or B diagram and you must then terminate the opposite end the same way to be consistent.

Actually most manufacturers of hubs, switches, routers, etc. are now using the 568A standard inside their product. But again, as already stated, as long as both ends are consistent, you're good to go.

The "A" method is the standard. The "B" method is the alternate standard. TIA/EIA could not use the "B" method or 258A as it was owned by AT&T/WECO at the time and probably still is. Inclusion into the TIA/EIA standards as the alternate was simply politics.

In the mid-90s Bicsi decided(?) to use 568A because the use of two pair telephone sets. Before that the standard was 568B because of the better data flow. Now, how will I prove this?
#1 --- Pull the sheath off of 100 feet of Cat 5 and measure each pair. White blue and white green will be almost the same while the white orange will be almost a foot longer. Remember that each pair is wound around it's self as well as wrapped around the other pairs. This is for wave form matching for harmonics. Remember wires on poles? Up and down and in and out on cross arms? Merlins used 568B wiring.
#2 --- As stated above, 568B was the original WECO standard due to data transmission, even inter office between C Os. Some of you old toll guys should remember the pinouts.
#3 --- Because it works! The "A" does okay but it was mainly pushed by the Asian telephone manufacturers as an universal wiring to benefit them. It was about the same time a bunch of equipment manufacturers wanted Bicsi to go to metric sizing for equipment racks.

Bicsi sets itself up as the true guidance for the industry while it actually is run by manufacturers and CGs because they control the money.

Remember, these are standards --- NOT codes. If your specs don't call it out, do as the Romans do.

My $1--298.

KLD

And Skip 555, B will only work with two pair telephones IF you x-connect white blue and white green --- not the telephone standard white blue white orange.

I've been involved with wiring longer than I care to mention, and 568B had been the standard until the 95-96 era. One of the Bicsi RCDDs that was on the board at that time worked for Bell Atlantic Network Integration out of Harrisburg, PA. He was also the guy who inspected my contract. I got to not only see the public side of the debate but the inside debate about converting from B to A. Same for getting rid of 19/23 inch racks and going to metric sizing for every thing. Politics. The end result was what we have here now. But that's just a small bit of history. All the digital sets are one pair now so who cares?

KLD :shrug:

I should have been clearer , 568b jack to patch panel . standard line cord config plugged into patch panel and it works fine .


if you terminate to a block then yes you will need to grab white blue and white green.

I still do a fair amount of partner (two pair) and thats what we do .

single pair it dont matter

Well I guess I can use a history lesson every now and then. I always figured the "Canada 568A, US 568B" business was myth. Having never worked in the US I was giving a textbook answer. My bad.

Actually most manufacturers of hubs, switches, routers, etc. are now using the 568A standard inside their product.

Huh? Care to explain that. Ain't no such thing anymore than there is a 568A and a 568B patch cord.

All equipment ports care about is if the pinouts are correct. They couldn't care less if pins 1&2 have the W/O or the W/G on them as long as it carries through to pins 1&2 on the other end.

-Hal

Sorry, you're right Hal, I shouldn't have said "using the 568A standard." They are using the color coding of the 568A and you are right, it doesn't matter as long as the pin outs are correct.

Even most premade patch cords are using the color coding of 568A now, again it doesn't matter as long as it is carried straight through.

And while on this topic;
How many have seen IT guys make their own patch cords and just crimp the wires in pairs from 1 to 8?

The copper doesn't care what color coating it has, it just wants to be on the right pin.
Mark

Aah, but it does matter. If you terminate in pair order, you have lost the twist on pair 3/6. Might be okay for 10baseT. Could slow down 100 because the unused conductors are not grounded and may actually bring in noise now on pins 3 and 6.

If you are doing PoE or gigabit ethernet, you are using all pairs and now they are no longer paired up correctly. Again, may cause noise and may cause bad test results on a verifier.

I have seen patch cables made like that a few times. Usually if the NIC and the switch are both 10/100, they won't even negotiate a speed with that cable in the link. Slows things right down to zero.

I never use data jacks for voice its a big waste
and you are asking for trouble sure enough some
one will plug a workstation patch cord into it and throw
a dead short across the data pair have had a whole system crash in the past like that (jacks were already in place 568a bt the EC)and have never used data jacks for voice again I put 2 usoc rj 14's on instead.

In Oregon mostly 568B and NO BIX.

Aah, but it does matter. If you terminate in pair order...

Don't think anybody here is advocating splitting the pairs. As long as pins 1&2, 3&6, 4&5 and 7&8 are on pairs it won't matter what colors you use.

-Hal

I always check out what type of hardware is being used at the customer sites I visit. Mostly 110, data jacks and 66 blocks. Some BIX, but not a whole lot.

Verizon New England has gone Krone krazy. They tend to use Krones for new demarcs as opposed to the old familiar RJ-21X.

In our Central Office, all wiring is 568B, so I tend to stick with it for any wiring job I do (work related or personal). I've pretty much given up on making patch cords and now use pre-mades whenever possible.

568B everywhere here.

unless, it's sparky

Sparky is the only one that uses 568A around here.

It's a wiring standard, like any standard it's meant to make it easy to follow the person before and make it easy on the person after. Same thing can be said about the color code, you can splice any color to any color as long as you do the same thing on the other end. Back in the old days we had people that would purposely change wiring on 1A stuff for "job security", dumb then dumb now.

Chad..I'll stick my neck out. Terminate your jacks and your patch panel 568B. If you purchase patch cords they will work perfect even if they have 8 colors of wires in them we have never seen. Chartruse..Jasmine or Black it don't matter as long as they are in the same order on both ends.

My mentor in this business taught me long ago that electricity is color blind. In fact it is completely blind. It follows a path. In this case a copper path. The color code is what humans use to create the desired path.

Just a tidbit of info. If you ever need a crossover cable. It will be 568A on one end and 568B on the other.

I can vouch for how bad a custom wiring job can be for the person after.

During one of our mergers, we inherited a POP site in Manchester NH. The site had a dead Stromberg switch, several muxes, DSX panels and a Tellabs 1/0 DCS.

The "nice" technicians (who quit right after the merger) had about 50% of the jacks on the various DSX panels wired "bass ackwards" with transmits & receives flipped. There was just about "0" documentation

It was so bad that my boss traveled from Boston to Manchester every day for 1 week trying to document how stuff was wired.

Needless to say that traffic was migrated out of that site very quickly.

Chad, Everyone here has a point. As long as both ends are the same, it does not matter. However, I would look at any existing terminations, and the back of the patch panel (As these also come 568A or 568B). Also, a big consideration would be Customer preference. Since they are the end user, what do they prefer?

As far as standard, there realy isn't one, but the most popular is 568B.

Everything I have come across in Houston, TX. is 568B. We still service old 2-pair phone systems & when we move one to a new site that has been cabled by a "cabling" outfit, they pull cat-5 everywhere & terminate 568B.

Many a late night trying to use old cabling because the boss was to cheap to survey the site & I have had a mix of 568A & B jacks!

"Old 2-pair pone systems".

That's kind of funny. Seems as if 25 pair or more was perfectly acceptable for 40 years, then 4 pair pretty much happened overnight.

3-pair systems lasted a little while, but 2-pair systems still exist today, brand-new, out of the box!

568A, 568B, 568C whatever it takes!

I wanted to throw a comment in here on this too ( a comment besides the Mr. Mom 220, 221 reference.) Most everybody on here will know this but just in case someone comes across this post and doesn't know. No one has specifically spelled this out yet.

If you get in a bind on a service call and have to replace a jack. After looking at the patch panel you discover it's A and you only have B jacks on you truck, or vice versa. Just swap the orange and green pairs at the jack. I've had to do that more than once in my past technician life. I also always tried to scribble some kind of note inside the box or faceplate as to what I did. So the next tech behind me wouldn't get too bumfoozled by my creativity.

The standards state quite clearly:

ANSI/TIA/EIA-568-B.1 Section 6.2.1
"Pin/pair assignments shall be as shown in figure 61 (T568A) or, optionally, per figure 62 (T568B) if necessary to accommodate certain 8-pin cabling systems. The colors shown are associated with the horizontal distribution cable.

NOTE - US Federal Government publication NCS, FTR 1090-1997 recognizes designation T568A only."

T568B was added as an alternative to support then then installed AT&T base of 258A back in 1990.

If you ever do any residential cabling, then you need to look at ANSI/TIA/EIA-570-B which states in Section 5.2.3.1: "At outlet locations, UTP cable shall be terminated on an eight-position T568A telecommunications outlet/connector."

Now from a practical point. In nearly all RJ45 connector designs, the worst performing pair for Return Loss is 3,6. There are exceptions. Now find out which is the worst performing pair for Return Loss on the cable.

If the cable's worst pair for Return Loss is the green pair, wiring to T568B is not the best choice for optimum test results. You just put the worst performing cable pair with the worst performing connector pair.

However, if the cable's worst pair for Return Loss is the orange pair, wiring to T568A is not the best choice for optimum test results.

If the cable has equally distributed Return Loss performance across all pairs, then you will not see a performance difference.

Welcome to the forum Adrian

Thanks for the input. Feel free to help out and enjoy this great forum

Adrian, to the board.


While the 568A vs. 568B has been going on for years, a group of people started a group in Massachusetts back in the 80's that would have cured the whole thing --- and your company bought them out in the mid to late 90's. They believed that copper should be outlawed and do nothing but fiber optics to the desktop. They manufactured fiber equipment.

Have a good time, kick around the forums, and, sometime when we have nothing to do, we'll discuss the parameters on the "A vs B" per manufacturer.

KLD

Thanks, ALL, for the info, btw CCSGINC, I _am_ the end user!

Chad B., you will undoubtedly be one of the better end users for we the installers of cabling. Why? Because you were un-afraid to ask, and will obviously put this information to good use.

Set a standard that works for you, spec it when you have work done, find a comfortable fit with a vendor, and good luck to you.

KLD

Regarding the comment about pair length difference in a 4-pair cat 5. Everybody sit down and consider this: The 25th pair of a cat5 25pr feeder is twice the length of the cable if you split it out and unwind the twist. BUT IT STILL WORKS!
This is what they called Fantasy Land in the USAF when they started talking about wave guides. What is really happening is the signal is transmitted like RF and sorta floats along the twist in a straight line.
I'm sorry, I should have apologized in advance for the headaches!
John C.
ARE WE HAVING FUN YET?

A is better for four wire telephones means the blue is on 4&5 and Orange on 3&6 meaning you can use a standard line cords with the 4 conductors in the centre of the RJ 45 plug.

What’s important is to keep track of the pin numbers as long as you have the voice pair on 4&5 and the Data Pair on 3&6 Who cares if the outlets are A or B. I like to use B because it makes more sense to terminate your cables Blue Orange Green Brown.

Anyway who puts in Analouge 4 Wire handsets anymore?

Anyway who puts in analog 4 Wire [phones] anymore?

A phone is not a handset. A handset is the part of the phone that you hold in your hand. Lets get the terminology correct.

Customer calls and says they have a problem with a handset. I drive out to them bring a handset up to the 35th floor only to find a bad phone. Customer says that's what they were talking about.

Many systems do use 2 pair and there are even more out there that you will have to service.

-Hal

Hal, in many other parts of the world a phone is refered to as a Handset......

If you take notice that the person is from Aussy Land. Maybe, just maybe thats what a phone is referred to down under....

Hal, have a shrimp on the barby and relax......

I like to throw analogue 4 Wire Phones on the TIP.

I hardly see any about now.

Although I have been installing some 4 Wire Phones recently (IP Phones!)

Hbiss Sounds like you have to educate your customers not me. I'm sure you had that other piece of Correctly Named Telecommunications Equipment you needed in your Truck?

568a or 568b?
If it is just an add job follow what standard is already in place.If it is a new construction then you set your standard.568a or 568b

Jamey

I've been in the cabling industry for about 12 years as a tech, PM, estimator, and consultant. In all of this time I have rarely seen a 568A install.

This could be because I'm originally from California (just moved).

I think it is more of a regional thing. I hear that on the East Coast 568A is popular.

Both standards are a straigh-through pinout configuration. As long as both sides are termed the same way you will have connectivity.

Most patch panels and jacks these days have color codes allowing either method. Some of the older patch panels have the color-code on the actual plastic 110 IDC terminals. If you have one of these patch panels then you will want to wire it according to the displayed color code. Flipping the orange and green in this instance could cause confusion to the next person who sees it.

I USE 568B 99.9% OF THE TIME