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acadiel
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join:2002-06-22
61705
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1 edit

T568A wiring vs T568B, which do you use?

I have a fairly recent house that has Cat5 cable wired to all phone jacks in the house. The wire (for now) goes to a 4x10 punch down telephone module in a Pass/Seymour home network center. (See here: »www.passandseymour.com/products/···?c=F7553 )

I do not feel like running additional Cat5 cable in this finished house. Therefore, I am going to recable the telephone outlets with RJ45 connectors (since RJ11 connectors work fine in RJ45s) and terminate them on the Home Network center side with RJ45 connectors and a 4x12 Plug/Connect Telephone module (RJ45 connector). That way, I can theoretically unplug a "phone" connection and replug it into a switch as a "data" connection for a computer, Tivo, whatever.

I've found two wiring standards that are used. T568A and T568B. I yanked out a few Cat5 cables, and saw that most of them used the T568B method. The back of the Cat5 P&S jacks mention 568A, but say just to switch the orange/green pairs to make it 568B.

Anyway, the pinout is still going to be the same since I'm using the same standard on both ends (and can use T568A or T568B). However, I'm just curious as to what everyone else is using and why you use it? Google has tons of webpages on this, but I'm looking for practical information from any of you that might have had experience with this as well.

Thanks, everyone!


nguyen27

join:2003-05-14
Quincy, MA

568B is more standard than A, but both work the same and great as long that you don't punch one end A and other end B I guess there isn't really an explanation why B but not A or vice versa.



tschmidt
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Milford, NH
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reply to acadiel

T568B is common in the US because it is compatible with older telephone gear.

TIA/EIA recommends T568A for new construction and is common in rest of word. The advantage of A is the inner two pair map directly to telco wiring practice.

Electrically it does not matter.

/tom



TerryMiller
Premium
join:2003-10-23
reply to acadiel

I use "B" but that's because when I first started doing wiring I asked my vendor what they sold more of "B" or "A" since both were standard. They said "B" so that's what I started using and just kept on. I'm not sure I'd get the same answer now.

Since you're starting from scratch and doing it yourself why not go with the "A" standard. It's more accepted worldwide.

Also I wouldn't use RJ11 plugs in RJ45 jacks. You're just asking for hard to track down intermittent problems.



Frank_IT
Premium
join:2003-11-01
Montreal

the only difference between the A and B, its the orange and green pair..

The blue (that can be use for phone), is always in the middle.
--
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acadiel
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1 edit
reply to acadiel

Thanks for the responses everyone. To prevent confusion on my part, I'll probably use 568B (since every Cat5 cable I've ever made was 568B! - I'm used to OW-O-GW-B-BW-G-BrW-Br!)

Also, do you really have problems plugging RJ11's into RJ45's? We do it all the time at work (I work at a extremely large insurance company). Never seemed to have a problem yet.

Thanks for the outstanding response - all of you are awesome!



jdepew
James Depew
Premium,VIP
join:2002-05-13
Savannah, GA
reply to acadiel

I recently completed the wiring for my parents new home. I had two Cat5e drops to most rooms and ended up with 18 cables to our central termination point. I terminated each jack using the T568A standard on Cat5e jacks and to the central wiring point using the same.

If you use A for the house runs that go from jack to termination point, you can use those jacks for either phone or data depending on where you go from the termination point since A, as mention before puts the orange pair in the correct place for the second telephone lines. There's no problem using that networking either as long as you terminate each end of a link with the same standard. You can use patch cables in A or B from computer to jack, and termination to switch/router/whatever, it doesn't matter.

From the termination point, you can either go to a switch or a telephone distribution panel and using the A standard allows that flexibility and expandibility if you wish to go to two phone lines at some point. I know today with the proliferation of cell phones, eFax, VoIP, and no need for dialup, that second phone line is needed less and less. But, its nice to be able to do it later if you want. So, no real downsides to either, just with A you have that option.

PS - depending on what product you use for your termination stuff, you may not have a choice and will most likely be T568A - all the Leviton stuff is.
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TerryMiller
Premium
join:2003-10-23
reply to acadiel

The sides of the RJ11/12 plug are unsupported in an RJ45 jack a little bump and you have bent pins that won't contact clean.



whizkid3
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join:2002-02-21
Queens, NY
kudos:9
reply to acadiel

T568B is almost universally used in the USA for commercial facility wiring. I have come across a few commercial buildings where the facility standard utilized T568A, but to me, it seems rare.

However, for residential wiring, the ANSI/EIA/TIA-570 standard, 'Residential Telecommunications Cabling Standard', should be followed. It indicates the use of T568A for residences.

In your case, since the majority of your pre-existing wiring is to T568B, you should stick with that. Although both will work fine, rather than needing to keep track of which cable is wired using which standard, go with T568B and the rest of your networking days will be happy ones.


phone guy1

join:2000-11-13
Rochester, NY
reply to acadiel

Use the "B" standard. I would use RJ-11's for phone and Orange or another color for the data. There are spares in the cat 5 one can use for telephone. White/brown pair comes to mind. I believe under normal uses, just the blue and orange pairs are used for data.



tr6scott

join:2002-03-23
Oxford, MI
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reply to acadiel

Just a heads up... all is well with 100 Lan but in 1000 Lan all four pairs are used, no spares. So you won't be making the next step in speed, unless you remove the phone from the network wire and get it onto something else...

Just something to consider, if you are doing some work, and plan on staying awhile...
--
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ernieJohnstn

join:2005-02-27
Lilburn, GA
reply to acadiel

ALL,
From: »en.wikipedia.org/wiki/EIA/TIA-568A

If the second line of a RJ-14, RJ-25 or RJ-61 plug is used, it connects to pair 2 (orange/white) of jacks wired to T568A but to pair 3 (green/white) in jacks wired to T568B. This makes T568B potentially confusing in telephone applications.

So the point of -A is to prevent puzzlement on the part of the BeLL Heads!

You can read the rest of the article if you want to know more.



winky
Turn Left At The Moon

join:2001-02-11
Saint Louis, MO

1 edit
reply to acadiel

Yeah I know you don't want to get into more work at this point but (but like tr6 said) consider just wiring for gigabit. you've got the holes, just whack another one on the other side of the stud, hole the wire and run a phone system. Unplugging and plugging will get old really quick. As for A/B I like to mix it up just to keep things interesting (and don't label anything; takes all the fun out)
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acadiel
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Winky,

The wiring in this house is already done, and inaccessible. After much thought and consideration, I reconsidered putting 568B, and will just do 568A so that the wiring color matches the back of the jack. I'll convert all my jacks to RJ45, and go to the patch panel side and crimp RJ45 connectors on those ends as well, and plug them into the RJ45 phone module (which has the capability for four phone lines.) If I need one for Ethernet, then I just need to plug it into a switch instead and will be ready to go.

As it is, I only have two telephones around here - my multi base station cordless phone and a fax machine. Everything else would potentially be RJ45 (Ethernet).

Thanks again everyone!



grcore
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reply to acadiel

said by acadiel:

Also, do you really have problems plugging RJ11's into RJ45's? We do it all the time at work (I work at a extremely large insurance company). Never seemed to have a problem yet.
Generally that's a bad idea, most rj11 plugs do not have recesses for 6-8pin jacks (although some do). It really depends on the durability of the rj45 you are plugging into. I have found that different manufacturers vary with their durability. Stuff by Leviton is not very durable, where AMP gear I have found is pretty tough.

I spec 568A exclusively for all installations. Although I find 568B slightly more common.


jeffmoss26

join:2002-07-22
Beachwood, OH
reply to acadiel

I always use B. I find that it's much more common.
Jeff