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On a CAT 7 Ethernet cable each twisted pair is individually shielded, and all pairs together are inside a shielded jacket:

enter image description here

Colors of the wires may change, for instance I recently got my hands on a cable where the wires were all different:

  • red & orange
  • yellow & brown
  • white & blue
  • black & aqua

When crimping a RJ-45 plug, should we follow the same order as in 568B, i.e. the four twisted pairs go to pins 1-2 4-5 7-8 3-6, as in the figure...

enter image description here

... or any order of the wires (provided they match at both cable ends, of course) will work fine?

In a CAT 7 cable, a wire is protected from crosstalk from its pair because of the twisting, and is protected from crosstalk from all other wires because of the double shielding, so I'd lean towards the second option.

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  • 2
    My take: even if it may be technically possible to wire the cable in a non-standard way, I think it's a good idea to be consistent with industry conventions. What if someone (or a future you) who has to re-wire one of the ends down the line wondering is why it's not working, and it was because it was wired in some arbitrary order?
    – mpontillo
    Feb 24, 2016 at 21:50
  • I fully agree with that but the 8 wires of the CAT7 cable have nonstandard colors.
    – dr_
    Feb 25, 2016 at 9:11
  • Ah, sorry, I was looking at the picture and totally missed that part of the question. I suppose I'd try to get as close as possible, such as o/ == red, g/ == black, g == aqua, b/ == white, br/ == yellow... and write down that convention somewhere. ;-)
    – mpontillo
    Feb 25, 2016 at 9:20

4 Answers 4

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Category-7 cable has not yet been recognized by ANSI/TIA/EIA. The only currently recognized cables are Category-3 (still talking about eliminating it), Category-5E, Category-6 (may not be recognized in the next revision), and Category-6A.

You are referencing an ANSI/TIA/EIA color code, so it is no surprise that un-recognized cabling has different colors. If Category-7 cabling is ever recognized, the manufacturers will need to adhere to the ANSI/TIA/EIA standards to be able to call the cable they produce by the recognized category.

If you are using this for ethernet, you will still need to follow the ethernet pinout of pairs: 1-2, 3-6, 4-5, and 7-8. Not pairing correctly will cause you no end of grief. Also, You need to make sure your equipment can proper ground the shielding. Most new equipment from the major manufacturers does this correctly, but some of the cheap stuff doesn't. Without proper connection of the shield in all the connectors (continuous the length of the cable, from one device to the device on the other end), and the shield is properly grounded on both ends, you wasted a lot of money on expensive cable that doesn't perform as it should.

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    While ANSI/TIA/EIA may not recognize it, ISO/IEC certainly does (along with Cat 7a & Cat 8). One will note that TIA is a involved with both ISO and IEC, so while they haven't accepted the standard themselves, they are involved in organizations that have. The wonders of different standards bodies and how they choose to operate with/without each other.
    – YLearn
    Feb 24, 2016 at 16:14
  • Right, but the point is that the OP is trying to use an ANSI/TIA/EIA standard color code on cabling that is not recognized by that group. It is apples and oranges.
    – Ron Maupin ♦
    Feb 24, 2016 at 16:15
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    ISO/IEC defines CLASS F and CLASS Fa. They do not define "category X" standards. There is no "Cat7"; anyone selling something as such is selling snake oil.
    – Ricky
    Feb 24, 2016 at 19:41
  • @RickyBeam, you are correct that they do specify classes, but it is my understanding they do also specify category components to match the classes. This is based on what I have seen/heard discussed in professional circles (including IEEE) and not first hand knowledge since I don't have access to a current ISO/IEC 11801 document. This 2013 IEEE presentation (see slide 5) seems to have the most clear statement about ISO/IEC adding Category 6A & 7A components into the 2010 version of 11801 that I was able to find quickly.
    – YLearn
    Feb 26, 2016 at 5:57
  • ANSI/TIA have stated they will not be matching ISO Class F (which would be Cat 7.)
    – Ricky
    Feb 26, 2016 at 20:50
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In a CAT 7 cable, a wire is protected from crosstalk from its pair because of the twisting, and is protected from crosstalk from all other wires because of the double shielding, so I'd lean towards the second option.

Umm no. The pair as a whole is protected from crosstalk with other things by a combination of the twisting and the use of differential signaling. The shielding helps a bit, too, but it's not the main line of defense (witness that most categories of twisted pair don't have it. The two wires within a pair most definitely interact with each other).

You need to make sure that the wires are paired correctly (that is that the pairs of pins that are supposed to connect to a twisted pair or wires are actually connected to a twisted pair of wires) or the cable will have terrible signal integrity and crosstalk, and will most likely be unusable for anything over 10BASE-T (and even 10BASE-T is probably a crapshoot).

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  • +1 as you're right about the crosstalk, my mistake. Concerning the "big problems", do you have any source (perhaps detailing the entity of the problem)?
    – dr_
    Feb 24, 2016 at 15:29
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    I don't have a source handy but if you have split pairs you will have massive crosstalk and horrible signal integrity. Last time I had a cable with split pairs (maybe 10 meters or so long) 100BASE-TX established a link but normal pings showed about 75% packet loss and large packets were worse.
    – Peter Green
    Feb 24, 2016 at 15:35
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There are many different color codes in the world, depending on where you are, which industry the cabling is intended for, and which companies' products you use. I am unfamiliar with any color code that matches the color-pairs you provided although the colors are used in some of them. Doesn't mean it doesn't exist somewhere, simply that I am unaware of it.

I have also come across cables that are bought because it is cheap that doesn't adhere to any color codes. The manufacturers use whichever colors they can acquire that happens to be the least expensive at the time. As a step up, I have seen cables that follow the color codes, but are inconsistent within the same cable (for example, first pair may be white/blue, second pair white-orange/orange, third a pale green/darker green, and the fourth a "translucent" brown/solid brown).

While you can sometimes get away with changing the order of the pairs, the pairs themselves must be maintained. If you mix individual wires between multiple pairs, then you negate the advantages of twisted pair wiring.

Twisted pair wiring is also sometimes referred to as balanced pair as the two individual wires in the pair carry equal and opposite signals which helps negate the impact of outside EMI and crosstalk.

You can find more resources by searching online, but I will provide Wikipedia links for quick reference if you want to know more:

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  • +1. Concerning your statement "(...) you can sometimes get away with changing the order of the pairs", how can you tell which pair is #1, #2, #3, #4 if they're color-coded differently?
    – dr_
    Feb 25, 2016 at 9:17
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Yes, the pin position and wire-pairs are set and must be consistent. You can not pick any two wires and call them a pair.

  • Pin position 4 & 5 are the first pair.
  • Pin position 1 & 2 are the second pair.
  • Pin position 3 & 6 are the third pair.
  • Pin position 7 & 8 are the fourth pair.

Pin Positions and Pairs

Edit: In Hindsight, everything I had wrote after this didn't really speak to the original question, so I'll edit it out and instead just leave links

In a CAT 7 cable, a wire is protected from crosstalk from its pair because of the twisting, and is protected from crosstalk from all other wires because of the double shielding.

The shielding helps with reducing inbound crosstalk, but the main protection against inbound crosstalk (otherwise known as EMI - eloctro magnetic interference). is simply the twists themselves. You can read more about how both Crosstalk and EMI is reduced here.

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  • The interesting thing about this picture is that it is incorrect in the pair numbering for T-568A. Cable installers and cable vendors will have heartburn over it. The accepted standard is: Pair 1=Blue, Pair 2=Orange, Pair 3=Green, and Pair 4=Brown, regardless of the pin position. For instance, Fluke has this, but you will find something similar at all the cable vendors.
    – Ron Maupin ♦
    May 17, 2016 at 23:33
  • A pretty vast majority consider Pair 2 of T-568a to be green -- which matches the picture above. I see that Fluke has the colors switched for T-568a/b, but from my research that seems to be the minority. Definitely wouldn't consider that one link from fluke authoritative enough to consider the image above incorrect... that is a bit of a stretch.
    – Eddie
    May 18, 2016 at 1:04
  • That was just an example, you will find that definition at just about any cable vendor site, and it is what is taught to designers and installers. The guiding standard is ANSI/ICEA S-80-576. It defines the color codes for all the cable pairs on UTP cabling. The ANSI/TIA/EIA 568 standard references it as the color code standard. In the standard, the Orange pair is pair 2.
    – Ron Maupin ♦
    May 18, 2016 at 1:14
  • This is directly from ANSI/TIA/EIA 568 - Commercial Building Telecommunications Cabling Standard (excuse the formatting, it is from a table): Pair 1 White-Blue (W-BL) Blue (BL), Pair 2 White-Orange (W-O) Orange (O), Pair 3 White-Green (W-G) Green (G), Pair 4 White-Brown (W-BR) Brown (BR)
    – Ron Maupin ♦
    May 18, 2016 at 1:58
  • The Orange pair is pair 2, regardless if it is pins 3 and 6, or pins 1 and 2. Most of the drawings from your link show this.
    – Ron Maupin ♦
    May 18, 2016 at 2:04

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