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While looking around for some plugs to use for running and crimping some bulk Cat-6 cable, I noticed the online sites show RJ-45 plugs for Cat-5e and separate ones for Cat-6. Is there actually any difference between the two? The Cat-6 plugs mention having an "insert", but does this really matter?

Last time I needed to crimp cable, it was for Cat-5e, which is why I'm asking this now. Thanks!

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For an example what I mean, see… - It mentions wire offsets for Cat-6 specs? – romandas Oct 30 '09 at 21:02

10 Answers 10

up vote 5 down vote accepted

"It depends". To the best om my knowledge the standards themselves do not mandate any changes to the plugs. I would guess -- but I'm not 100% sure -- that the standards are mainly concerned with externally observeable characteristics of the cabling such as crosstalk and attenuation, and leave the internal implementation details mostly up to each manufacturer. Having said that, the following comes to mind:

  • 23 gauge copper wiring (thicker wires) is more common in Cat6 installations than in Cat5 in my experience. If the wires are thicker, the plugs are different.
  • More and more manufacturers are updating their cabling systems, both to allow faster cabling work, and to ensure more consistent and/or higher quality. Many cabling systems now use a little 'form' to fixate the wires before the plug. This is to minimize crosstalk and noise near the plug (where the cable is un-twisted, and much more susceptible to interference).
  • See John Gardeniers answer regarding stranded / solid wiring; these should use different plugs. Solid wiring is often used in building wiring.

Regarding OPs link to a noname plug, I think it's mostly marketing. While there can and should be differences in how plugs are designed, in the no-name space I don't think you'll find a consistent set of differences between no-name Cat5 and Cat6 plugs.

Here is a little video that shows how some modern structured cabling systems use a insert / form. The same brand uses a "smart connector" for the 8P8C plugs as well. But this is a name-brand structured cabling system. Cabling systems will typically be installed by certified installators, and be validated end-to-end after installation by measuring that they meet or exceed a agreed level of performance.

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+1 and accepted. Thanks! – romandas Nov 19 '09 at 21:58

I just want to add one thing that nobody else has mentioned yet. There are also different plugs for use with either stranded or solid wires. Although you may get away with using the wrong one it is preferable to ensure the correct one is used, as it will give you more reliable cables.

The differences between these two types of plugs is in how the connector pin pierces the insulation and contacts the wire when crimped. For solid wire, which is cheaper adn normally used for fixed wiring, the insulation is broken on each side and the wire is wedged by side contacts. For stranded wire, which is preferred for patch leads, there is an additional middle prong which is designed to pierce the insulation and go between the strands, as well as the two side contacts.

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More info at this PDF: , and the relevant picture here: – p.campbell Oct 31 '09 at 18:06


Physically they may look the same but if you want an actual Cat 6 cable it's very unlikely you are making it yourself.

The tolerances for Cat 5e, in terms of amount of un twisted cable you could have in the plug, were tight already. Cat 6 and you don't really stand a chance.

You certainly can't make one with existing Cat 5e tools.

However it is worth noting that unless you are planning on pushing 10G ethernet over them ( up to 40M ) then you might as well use a Cat 5e cable.

Edit: Also I seem to remember when we kitted out a new data centre there is a recommended minimum total length of 15m which is mentioned here.

Also from the above

Category 6 Patch Cord Questions

Will contractors be able to make their own patch cords?

Category 6 patch cords are precision products, just like the cables and the connectors. They are best manufactured and tested in a controlled environment to ensure consistent, reliable performance. This will ensure interoperability and backward compatibility. All this supports patch cords as a factory-assembled product rather than a field-assembled product.

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You should probably take this answer with a grain of salt. You're asking a place who sells cabling if you should spend more or less money. – sparks Oct 31 '09 at 20:03
@sparks - That's why I asked the SF community. :) Hopefully, the community at-large can vote up the correct answer. A lot of the information on the web seems to be from companies who would profit from their answer being the correct one. – romandas Nov 2 '09 at 16:30
@sparks Whilst I've referenced a site that sells cables, I don't sell anything and this is correct from discussions I've had with people involved in the standards generation. To be fair "Will it work?" and "Is it guaranteed to always work?" are very different questions and it very much depends on the application which you need to ask. I think if these are mission critical connections that need Cat6 bandwidth buy ready made. – Dean Smith Sep 18 '10 at 17:25

Given the slightly lager gauge wire of CAT6 the RJ45s offset the wire entry, where the CAT5 RJ45s wire entry is flat. If you look at the RJ45 front on i.e. as if you were going to plug it in to your eye, you will see the alternate up/down wires of a CAT6 RJ45, as opposed to the flat configuration for CAT5 Rj45s. Note this is for field terminated RJ45s, manufacturers can produce products of greater tolerance and as such can be flat.

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No, they're the same.

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There are two types of RJ-45 (AKA 8P8C) plugs used to terminate Ethernet cables. Cat-6 and Cat-5e should work with either type. The only thing you have to look out for is the crimper/plug combination. If you have used your current crimper/plug combo to make working cables in the past, it should still work with Cat-5, Cat-5e and Cat-6.

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Understand that you won't be able to make something that's cat6 just by using cat6 qualified components.

Specifically when you're making your cables, you have to make sure that you put the ends together to minimize "near end cross talk". That may explain the differences in the cat5e vs cat6 plugs -- the cat6 plugs may have guides to maximize the pair separation and keep the pairs themselves twisted right up to the crimp.

Unless you test it after you make it, you should assume that at best it is cat5 or maybe cat5e. Don't assume you've got an infrastructure that's cat6 unless you test it.

Lastly -- why do you care about cat6? Are you really planning on running a 10gig to the end station sort of infrastructure? I'll make the wild-ass guess that by the time you really need 10gig to the desktop, they'll be able to run 10gig over cat5. There is too much out there to yank it all and the first group that does it is going to make bank...

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What manner of testing would certify the difference between Cat-5e and a Cat-6-quality cable? Obviously not just the standard 'do the pairs light up correctly'.. so what would be necessary? – romandas Nov 2 '09 at 18:01
Fluke and other companies have tools that you put on each end of the cable and it generates specific test signals that the other end verifies. Google "fluke cat6 tester" They're not cheap and they're not trivial to use properly, but they are the only to validate that your specific site is cat6 or not cat6. Without testing can't assume anything will work if it truly requires cat6. – chris Nov 2 '09 at 18:45

They are exactly the same physically.

Just beware that Gigabit ethernet use all pairs while 100Mbit Ethernet does not. Therefore if you have crappy connectors and/or cables, they may only support 100Mbit. That's the only difference I can think of.

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I agree with John Walker, and would go even further: Although I am not a professional, I have wired many homes, made most possible mistakes and learned the hard way. And now, I am cabling my old house and decided to go with cat6 cable. I do not know if all cat6 cables are identical, but I can promise you that there is no way to insert my cable in a standard rj45 plug without offsetting the wires, and that proves almost impossible to do without a guide. I am now looking for new plugs preferably with guide..

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Of course there is a difference! The ONLY way to insure a dependable CAT6 installation is with a Certification Meter. We do alot of CAT6 work for Boeing Aerospace and they require us to certify ALL CAT6 runs and provide printouts of same.

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