Wiring MEGAnoob question ... 568A vs 568B

[thecomputerguy]

I've repaired a handful of patch cables before because I had to but I try to stay away from any wiring unless I have to.

Every cable repair I have done I have always done it to the ti-568B standard (apparently more common?) and they have always worked (dumb luck maybe?). I have a picture I printed of ti-568B and taped to my kit so I can use it for reference.

I have a cheapo kit I got from Amazon that came with a crimping tool, some passthrough Cat5e/Cat6 jacks and I have a super cheap cable tester/toner, all probably from china.

I did a fairly large job for a client and I need to replace a wall keystone jack (you know one of those things that clips into the wall plate then that terminates at the patch panel.

I don't know how the current broken keystone is wired (I forgot to look) and I don't know how it's wired at the patch panel and don't really have access to look.

I have keystone jacks I got from Home depot that show a template for ti-568A. Now I know I don't have to follow the picture and it can be punched down with my little plastic punch down tool in any order but can someone give me a quick crash course on this? Internet says as long as both ends are the same it doesn't matter.

Does that mean Keystone -> Patch panel = ti-568b

Then the patch cable from Patch panel -> switch

Must ALSO be ti-568?

Or can Keystone to Patch be 568A and patch cable 568B?

Do I just say screw it and follow the template on the keystone I got from home depot and if it doesn't work undo it and 568B it?

 

[thecomputerguy]

You know why I'm getting so confused ... The keystones I bought from home Depot are 180 degree keystones so all of the diagrams online aren't making sense with what I'm holding in my hand.

I think I just need to buy a handful of new keystones where the cable is installed from the rear and not from the side.

 

[timeshifter]

The correct answer IMHO is always B.

 

[YeOldeStonecat]

In the ~ 30 years I've been doing this (I know..I know...28 or so years ago it was 10base-2 more often...lol)....99.9% of the time, in the USA, it's "B". I have run across "A" in few enough times I can count that on one hand. More often..those were government installs.

Want some good stuff to stock up your ends and tools? Simply-45 brand!

 

[nlinecomputers]

When it comes to keystones I’ve never seen one that wasn’t B. The punch down HAS nothing to do with how the jack is wired. Quit looking at sh!t online and punch it down as it is labeled!

 

[thecomputerguy]

When it comes to keystones I’ve never seen one that wasn’t B. The punch down HAS nothing to do with how the jack is wired. Quit looking at sh!t online and punch it down as it is labeled!

Yeah ... the keystone I have even though its a 180 keystone is labeled for A and B. I definitely could have saved myself some hassle if I just followed the diagram.

I just think it's important to spend the extra time to understand why it is the way it is so that it sticks in my brain longer. I don't want to be like me clients where I just mindlessly follow direction and if the path strays at all then brain shuts off.

But I learned the B is the way to go and they also make 180 degree keystones ... so good info to have! But you are also correct!

 

[thecomputerguy]

In the ~ 30 years I've been doing this (I know..I know...28 or so years ago it was 10base-2 more often...lol)....99.9% of the time, in the USA, it's "B". I have run across "A" in few enough times I can count that on one hand. More often..those were government installs.

Want some good stuff to stock up your ends and tools? Simply-45 brand!

Yeah I only need like 10 keystones so I just bought whatever amazon had. Chances are I'll be dead before I use all 10 keystones I bought. Issues like this usually come up once every 5 years where I have to wire ONE cable or ONE keystone.

So the jacks, keystones, and punchdown tools are nice to have but not worth much of an investment since I use them twice a decade.

Oh and I'm dumping these 180 degree keystones. I think I got them from Home Depot and it was all they had 8 years ago ... the last time I needed them.

 

[JoelM]

The only thing that matters is from keystone to patch panel. I have only ever used B in all my years of doing cables. However, I got called by a contractor about 10 years ago who was remodeling a couple of rooms in a city building. The electrician had punched down the new keystones in the wall jacks in the rooms as B but nothing would work when plugged into the jacks.
I got called to come figure out what was wrong. I plugged my tester into the wall jack and the other end in the patch panel. Keep in mind the patch panel end had not been touched and was still punched down as it had been before the remodel. My tester failed on testing the pairs showing a miswiring on the pins. Closer examination found the entire patch panel was punched down as A. I went back to the jacks in the remodeled rooms and rewired all of them to A and everything passed with no issues.
So if panel is A then keystones need to be A
If panel is B then keystones need to be B
If you don't know what the panel is for sure then punch down one keystone and test it to the panel. If it passes then you guessed correctly. If it fails as a miswire the punch it down the other way and test again. Once you get one to pass you will know for sure which it is.

 

[thecomputerguy]

The only thing that matters is from keystone to patch panel. I have only ever used B in all my years of doing cables. However, I got called by a contractor about 10 years ago who was remodeling a couple of rooms in a city building. The electrician had punched down the new keystones in the wall jacks in the rooms as B but nothing would work when plugged into the jacks.
I got called to come figure out what was wrong. I plugged my tester into the wall jack and the other end in the patch panel. Keep in mind the patch panel end had not been touched and was still punched down as it had been before the remodel. My tester failed on testing the pairs showing a miswiring on the pins. Closer examination found the entire patch panel was punched down as A. I went back to the jacks in the remodeled rooms and rewired all of them to A and everything passed with no issues.
So if panel is A then keystones need to be A
If panel is B then keystones need to be B
If you don't know what the panel is for sure then punch down one keystone and test it to the panel. If it passes then you guessed correctly. If it fails as a miswire the punch it down the other way and test again. Once you get one to pass you will know for sure which it is.

Excellent info ... thanks! So I'm assuming if Keystone A and Patch Panel A match then the patch cord you use doesn't matter (as most if not all of them are wired B)

right?

Something about it creating a cross over but 99.9% of 1Gb connections will auto negotiate it?

 

[Big Jim]

no it doesn't matter.

 

[Sky-Knight]

T568A is historically used for voice applications.
T568B is historically used for data applications.

The only difference between the patterns is flipping the positions of the green and orange pairs.

Both standards are based on old analog phone connections, which is why blue is always in the middle. That's "line 1", the split pair flanking it is "line 2", the pair to the left is "line 3", and the final pair to the right is "line 4".

But that's mostly all useless trivia these days. All you really need to know is if you expect a patch or straight through connection, that is 1-1,2-2,3-3,...,8-8, you need to ensure the same pattern is used on the patch panel side vs the jack side. I've worked in many places that used A everywhere, many more that used B everywhere, and more than I care to admit that used BOTH (A for voice, B for data).

Then there's the real fun... older buildings that have been remodeled a few times, and different sections of the building use different patterns because the builders couldn't be bothered with keeping things consistent.

So if you're going into a building to add new wire, check what's there and make it match please!
B is the "more normal" pattern for modern builds.
Keep an eye out for oddballs.

@thecomputerguy A cross over cable is substantially more than just swapping orange and green, so no full MDIX interfaces (default in Gbit adapters) may not be able to "figure it out."

 

[Markverhyden]

T568A is historically used for voice applications.
T568B is historically used for data applications.

The only difference between the patterns is flipping the positions of the green and orange pairs.

^^^^ This. When I first got into this some 25 years ago I asked a VZ tech that happened to be onsite which said that was the reason. But there is no real technical difference between switching the orange and green pairs. Supposedly it was to prevent confusion but if you can't see whether it's A or B without taking things apart I fail to see the value of it. Anything I do thats new is always B. With existing sites I'll always make note of what's being used. If you're at an older site take note if the port labels have V (voice) and D (data) as they might very well be terminated at different patch panels. The installers might have used A for the V runs. Either way I always test all my work. Also I stay away from the bottom dollar online keystones and jacks. Several purchases were trashed due to very high failure rate. Since then I've always purchased from a local distributor and have had zero reliability problems.

 

[Mercenary Roadie]

In the States, any government job will probably be 568A (but not always), and most commercial and residential jobs will be 568B.

Which one is the correct one to use? They are both correct, but standard industry practice is to use 568B.

When repairing a drop, you must verify which is being used and use the same in the repair. If you can not determine which is being used, look at a nearby drop and use the same wiring.

These are not hard and fast but will work 99% of the time.

 

[thecomputerguy]

In the States, any government job will probably be 568A (but not always), and most commercial and residential jobs will be 568B.

Which one is the correct one to use? They are both correct, but standard industry practice is to use 568B.

When repairing a drop, you must verify which is being used and use the same in the repair. If you can not determine which is being used, look at a nearby drop and use the same wiring.

These are not hard and fast but will work 99% of the time.

Nice thanks!

I'm right up the hill from you. My Office is in Simi and my residence is in Moorpark. Nice to see another local tech! Maybe we should touch base sometime!

 

[DRPCNZ]

Years ago here in New Zealand Commercial was always A and residential was B DON'T ask me why I have no idea was just a case of always check if you were repairing cable in the building

 

[Mercenary Roadie]

Nice thanks!

I'm right up the hill from you. My Office is in Simi and my residence is in Moorpark. Nice to see another local tech! Maybe we should touch base sometime!

Slimmy Valley and Kraproom. I feel for you.

 

[thecomputerguy]

So I go out there to replace the broken keystone and thankfully the old keystone was still there, just broken... what do we have?

568A?

NOPE

568B?

NOPE

Custom wiring pinouts apparently



From left to right ... thats

Left:

Orange
Orange Stripe
Green Stripe
Blue Stripe

Right

Brown Stripe
Brown
Green
Blue

I just re-did the same pinout on the new keystone.

 

[nlinecomputers]

So I go out there to replace the broken keystone and thankfully the old keystone was still there, just broken... what do we have?

568A?

NOPE

568B?

NOPE

Custom wiring pinouts apparently

View attachment 14648

From left to right ... thats




I just re-did the same pinout on the new keystone.

Did you test. Because as I said before what you punch down on the block side has NOTHING to do with how the jack is wired. For almost any site you are much more likely to encounter B. Wire YOUR JACK as IT IS LABLED because different brands may be layed out differently. The standard is on the JACK NOT THE PUNCH BLOCK!

 

[Markverhyden]

So I go out there to replace the broken keystone and thankfully the old keystone was still there, just broken... what do we have?

568A?

NOPE

568B?

NOPE

Custom wiring pinouts apparently

View attachment 14648

From left to right ... thats




I just re-did the same pinout on the new keystone.

What really matters is which pin got to what punch down. Was there a label on the side or underside. Most have that. As @nlinecomputers they are not all the same. Occasionally have a bump in the road when I neglected to look at the labeling for each punch on the side. Get used to one order then it changes. Like re-arranging furniture on a blind person. LOL!!