Talk:Category 5 cable

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[edit] Crosstalk reduction

While "twisting of the cable reduces electrical radio interference" is correct(-ish), I don't think that the "which causes crosstalk" at the end of the sentence makes any sense. Surely crosstalk is between conductors in the cable and therefore cannot be caused by external sources (including RF interference)? —The preceding unsigned comment was added by 212.1.146.16 (talk • contribs).

Quite so. I took a crack at correcting this. dpotter 00:29, 25 January 2007 (UTC)
Ethernet is WELL into the radio frequencies so yes rf can be radiated by one pair and picked up by another. Afaict twisting reduces both rf emmision and rf pickup as well as some other forms of interference between conductors. Plugwash 18:49, 21 March 2007 (UTC)

[edit] Insulation type

I could be wrong, I have not seen the spec, but I believe that there is a critical piece of magic in the choice of the insulation of the wires. I think that FEP teflon is used because it has a low dispersion, and that this is critical to extending the useful distance that these rather wideband signals can propagate. I am sure they would use something cheaper if they could. Clearly, the teflon is not used for fire resistance, since the jacket is often vinyl. Dispersion is sometimes called delay distortion in this realm. It occurs when the index of refraction (or dielectric constant) changes over the frequency range of interest, causing pulse-like waveforms to spread out in time. If this is true, it might be fun to mention it.jkgjkjkggjkgjkgjk AJim 23:13, 16 Mar 2004 (UTC)

AJim, that's an interesting comment, but the rating of the cable deals with it's sheathing which - of course - plays no role as a dielectric. Teflon is chosen for it's high smoke point and lack of noxious gases. Regular cable uses PVC which has a low smoke point and emits noxious fumes. Teflon sheathed cable has the added benefit of not needing "cable lube" when running through conduit although no one uses it purely for that attribute due to cost. Cataclysmcow 1:51, 08 May 2005 (MST)

[edit] Distance limit

The statement that Cat5e is limited to "350 m, compared with 100 m for Cat5" in relation to 100Base-T is incorrect. The effective distance of any wiring plan is dependant on the signaling scheme used. In ethernet the maximum length is dependant on the propagation delay of the medium. This propagation delay remains mostly constant for all UTP. The effective length of ethernet over any UTP is 100m. Cataclysmcow 8:58, 08 May 2005 (UTC)

isn't propogation delay only an issue for the half duplex variants of ethernet? Plugwash 21:01, 17 July 2005 (UTC)
A quick search turns up numerous sources claiming the maximum length to be 100m (328 feet) for category 5 and 5E twisted pair. I think perhaps someone got confused with Cat-5E operating/rated at 350MHz. --Southen 06:51, 24 September 2005 (UTC)
Moreover, cat5e, cat6, cat7 and very likely whatever there is to come can not guarantee distances over 100m for 100Mbit links. All higher categories are backward-compatible, but chances of getting 100Mb working over 100m+ links can actually be diminished by upgrading to cat6/7. The 350m statement should be erased from the article and the opposite should be added. I'll do it later if no one steps forward before.

[edit] Photo

The article says that the Cat5 standard is an unshielded cable. Correct me if I'm wrong on this, but isn't that a shielded cable in the photo? --Xcali 03:28, 15 Jun 2005 (UTC)

I'm pretty sure you're right. The shielded connectors are certainly misleading, even if the cable itself isn't shielded, so I've replaced the picture of the (probably) shielded cable [1] with the one we had before [2]. --Elembis 00:43, Jun 18, 2005 (UTC)
afaict most suppliers sell category 5 UTP (unshielded twisted pair) and category 5 STP/FTP (Shilded or foiled twisted pair). I don't know what the original standard says though. --Plugwash 21:19, 17 July 2005 (UTC)
The original photo was tagged for deletion, so I replaced it with a higher resolution one with a free license. --Fo0bar 02:12, 1 September 2005 (UTC)
I will try to use 110 M CAT5e cable to join with a D-Link Switch for Internet sharing purpose, I expecte some slower speed becasue of the distance.I will be happy if someone can advice me how to deal with this problem.

[edit] CAT5/ CAT5e

There's no information in the article as to the difference between CAT5 and CAT5e. Just that it's "enhanced" and has "tighter specifications." 128.111.207.145 18:08, 19 April 2007 (UTC)

So you cannot take Cat5 or CAT5e over 100m? How is the VoP of a certain ethernet system figured, For example; if I needed to run CAT5 of CAT5e up 16 floors, or 160ft and across 160ft that makes 320ft. Is that possible? If I can find the VoP of the system then CAT5e should be able to run the distance as I understand it??? Otherwise I am stuck setting up a new T1 line and then having to set up everything else that comes with stand free network. Any ideas and suggestions would be much appreciated.

use one of the fiber variants of ethernet? while they are far more expensive than CAT5 for a link between cabinets it shouldn't be prohibitively expensive. Plugwash 21:00, 17 July 2005 (UTC)
Wiki is not the right place for you to find solution. Anyway, for your case, you can either use a repeater to extend the signal, or use another switch to extend the signals.

[edit] Twisted Pairs

The article implies that all 4 pairs are used for both 100 & 1000. CompTIA Network+ text tells me that all 4 pairs are used only in the 1000Mbits/s environments. I think that the 100 uses only two pairs. —Preceding unsigned comment added by HarryAlffa (talk • contribs) 10:29, 31 March 2008 (UTC)

[edit] Solid vs Stranded

There isn't any discussion in the article of solid vs stranded. Is it the case that solid is generally used for infrastructure, and stranded is generally used for patch cables?

yeah thats what you are supposed to do. i've made patch cables with solid before though and it doesn't seem to be a problem. Never tried to terminate stranded to a wall port but i don't think it would work very well with the type of IDC the wall ports use. Plugwash 21:24, 17 August 2005 (UTC)
Patch cables with solid wire have a risk of developing intermittent connections. Kd4ttc 03:32, 27 July 2007 (UTC)

It's important to use the proper type of connector. There is a difference between connectors for stranded and for solid wire. Much of what is sold is only for stranded wire. Using these connectors for solid wire will result in an intermittent connection. 98.204.103.241 (talk) 01:16, 29 December 2007 (UTC)

[edit] Not funtioning

cat 5 cable, i was used about 50 metes for my VOIP video phone but its not functioning ....? —Preceding unsigned comment added by 210.19.204.210 (talk • contribs)

Most likely causes are bad connection damaged cable and split pairs. after checking it is wired correctly try re-terminating it using the other two pairs as the signal carrying ones. Plugwash 19:56, 20 February 2007 (UTC)

[edit] Connection Diagram

Maybe this is the wrong place for it but should there not be some connection diagrams here ? Ok found it on the RJ45 Page

[edit] 568A v B

According to the TIA 568A and B page, both are electrically equivalent. From this I judge that the section which describes one as straight-through and one as crossover is incorrect. Is this correct? --69.207.105.212 03:23, 11 October 2005 (UTC)

Yes. There is absolutely no functional difference between the two. A straight-through cable has the same type (A or B) on both ends and a crossover has A on one end and B on the other.--Roofus 06:53, 11 October 2005 (UTC)


I rewrote the section. It should be more accurate, even if it's not particularly eloquent.  :P--Roofus 07:02, 11 October 2005 (UTC)

[edit] Cabling guide

In the external links section there is a link to http://www.linux.ie/articles/tutorials/networking.php. That page was written in 1999 (over 6 years ago now), and presents 10Base-T as a new and better choice (hellooo? 100Base-T and GbE anybody? 3rd millennium?)

Is there any reason why this link should be listed here instead of a "history of networking" page?

Aditsu 07:04, 15 February 2006 (UTC)

It's still got some good information on it. The cabling procedure hasn't changed. --Roofus 15:06, 15 February 2006 (UTC)
What has changed is the care you must take to get the cabling right if you wan't the faster speeds (especially gigabit) to work properly. Plugwash 14:02, 12 June 2006 (UTC)

[edit] Technical Specs

I haven't had sight of the specs so I don't know what the numbers should really be, but I think they would be useful to have on the page:

Property Nominal Value Tolerance Unit
Characteristic impedance @ 100MHz 100 15 Ohms
DC-Loop resistance 170  ? Ohm/km
Velocity ratio 0.69  ? speed of light
Capacitance 300  ? pF/km

Are there any objections/corrections? AndyP 13:46, 12 June 2006 (UTC)

[edit] What is the Ripcord inside most cat5e cable for?

No one has discussed this topic, or even mentioned that cat5e cable usually has a ripcord inside in addition to the copper wires. What is this ripcord for? To tear the cable open lengthwise? —Preceding unsigned comment added by 131.212.109.27 (talk • contribs)

Yes, that's exactly what it is for. dpotter 23:59, 15 September 2006 (UTC)


Define cat5e Ripcord: When cutting the outside insulation of cat5e in order to expose the inside wires, it is common to nick/cut the insulation on the wires prior to crimping an attaching connector. The "Ripcord" allows the inside cord (not wire) to be pulled through the insulation to expose the rest of the wire w/out the risk of random cuts. Todays connectors rely on the insulation to be intact rather than "stripped" off in order to hold a connection in place. The "Ripcord" idea is to manually pull down the string to clear insulation with zero risk of exposing open wire to a short from cut insulation.

I must now say that a small cut before attempting to bend the plastic insulation to it's breaking/cut point is timesaving. That, or strip a good handful of wire before using the "Ripcord." Rip cord is good. 68.218.61.120 09:47, 8 February 2007 (UTC)

I thought the fiber strand was to keep the cable from being stretched and changing the characteristic impedance. Kd4ttc 03:37, 27 July 2007 (UTC)

[edit] Wiring diagram

T568B wiring diagram
T568B wiring diagram

Is this image correct? - Zephyris Talk 15:27, 3 March 2007 (UTC)

According to the text in the image it is a view from the bottom with the tab down, that would make it a view from the tab side (though its a very confusing way to label the image) read that way both the pin numbering and conductor order are backwards. Plugwash 18:03, 3 March 2007 (UTC)
Which way is "up"? Is the lock-tab on top (which would make the diagram correct), or is the lock-tab considered to be on the bottom? Various workstations, servers, patch panels, switches, hubs, routers, and wall plates have them both ways, so is there a technical "right-side-up" to these or not? 10:54, 12 March 2007 (MST) —The preceding unsigned comment was added by 199.67.138.242 (talk) 17:55, 12 March 2007 (UTC).
Most diagrams I've seen have the tab side down. -Roofus 04:24, 14 March 2007 (UTC)

It was removed from the article for being incorrect - it seems correct and useful!

One could argue that it's incorrect because the connector shown is not an RJ-45 connector. It's an 8P8C. 128.111.207.145 18:07, 19 April 2007 (UTC)


[edit] Turns per inch?

I was taking apart some Cat5 cable and noted that the turns per inch are different for each pair. Is that a part of the Cat% spec to improve crosstalk resistance? Kd4ttc 03:41, 27 July 2007 (UTC)

I belive it is but I don't know where to find details. Plugwash 14:00, 4 October 2007 (UTC)

The reason for using twisted pairs is that any magnetic field impinging on the twisted pair induces offseting voltages in each twist. Other than the end effect of using only half a twist, these voltages cancel. If all the pairs were twisted evenly, the magnetic fields very likely would all line up and produce a great amount of cross talk. If the pairs are twisted at different intervals, then the magnetic fields (and corresponding induced voltages) cancel, other than for end effects.

At some interval these twists approximately repeat themselves. If you have a very bad cable and the cable is in a difficult run, but is undamaged, never kinked and is in pristine condition, one thing worth trying before scrapping the cable is to cut off a little under half of the repeat length and reconnector. This would dramatically change the crosstalk (for good or for bad) in a given piece of cable!

Aaden@AOL.com

[edit] cat5e testing

when testing cat5 cable there are 4 tests which are done 1)wire map - which checks that all coloured cores are in the correct position. 2)length - which checks the length of all cores to ensure no brakes. 3)next and 4)attenuation - which has something to do with powerbands i think, but does anybody know what tests 3 and 4 actually mean.

Rob 11/1/2008 —Preceding unsigned comment added by 81.159.251.151 (talk) 20:43, 11 January 2008 (UTC)