This is Lars -> Professional -> Telecom -> cat5wire.htm

Category 5 cables and connectors

(See also http://www.futurestandard.com/faqs/simplecable.html

Category 5 cable is used for both telephone wiring and data network wiring. It exists in two very different types: Solid conductor and stranded conductor.

Cable types

There are three different types of cable. Unfortunately, you can buy a 1000 foot spool, and it won't say on the box which kind it is; you have to feel the cord, flexing it to see how stiff it is.

Also, any of these types tend to be available with PVC jackets or Teflon jackets.

Round, solid conductors

Solid conductor cable is meant to go in the wall. It is stiffer than stranded, and the solid conductors work well with the 110-type punchdown connectors on the back of wall jacks and with the 66-type punchdown blocks on a plywood board. It does not work well with the modular plugs that you crimp on the end of a patch cord, and the solid conductors are prone to break when a loose cable is handled, kinked and stepped on.

Round, stranded conductors

Stranded conductor cable is softer, and is meant to be used for cords running around in user space. It does not work well with punch-down connectors, but works fairly well with crimp-on plugs.

Flat satin, stranded conductors

There is a flat version of the stranded cable, but it should not be used for data networks, because it is not twisted pairs, and thus subject to noise injection and noise radiation. Use it only for patch cords less than 10 feet, and not for 100 Mbps.

PVC or Teflon?

Most data cables have PVC jackets for insulation, but recent fire safety codes forbid the use of PVC in areas used as air plenums for ventilation systems, because PVC gives off hydrochloric acid gas when it burns. In these areas, Teflon cables must be used. However, they are enough more expensive to prohibit their general use outside of those areas.

Category 5 PLUS

The original cable used for inside wiring for telephone systems is known as "4-wire station cable"; since data networks have become common, it is known as "category 1".

Category 2 is a shielded twisted pair cable, which was mostly used for token ring.

Category 3 is shielded twisted pair approved for 10 Mbps ethernet.

Category 4 I don't know.

Category 5 is also unshielded twisted pair with more twists per foot, certified for 100 Mbps ethernet applications.

Eventually, there will be a standard for 622 Mbps ATM and for gigabit ethernet use. Some cable manufacturers are producing cable for these applications, which they call "enhanced category 5".

Cables for T1

It would seem that a standard run of Cat 5 wire would work for T1, but telephone companies will not allow that due to crosstalk. For T1, you must use a cable where each pair is separately shielded.

Price versus quality

Sample prices:

Connectors

The standard connector for network cabling is an 8-pin modular plug, crimped on to the 4-pair cable. The cable has 8 color-coded wires, and they go like this when you look at the cable from the side with the locking latch: 
+-----------+
|           1 white/orange
|           2 orange
|           3 white/green
|------+    4 blue             (cable sticks out this way)
|------+    5 white/blue
|           6 green
|           7 white/brown
|           8 brown
+-----------+
Of course it is easier to see the wires from the other side of the plug. (Image taken from Cabletron's support site.)

Note that there are at least 3 versions of the connector, which look exactly alike to the naked eye, and are generally not marked clearly. If you use the wrong connector, it will tend not to work: Your connections will be flaky and need to be seated just right, then wiggle out of place when you turn your back. These variations are:

  1. Flat cable, stranded conductors
  2. Round cable, stranded conductors
  3. Round cable, solid conductors
Graybar tends to carry all of them, but I have often seen them only have one or two of them in stock for a day or two. This is when you get in trouble. Unfortunately, the suffix "SC" can mean either solid or stranded conductors, depending on the vendor.

Tools

The most important tools are The samples shown here are all manufactured by Allen Tel, but the same tools are available by a variety of vendors.

Crimp tool for modular connectors

These tools are available in a variety of price ranges; generally the better tools are more expensive, and they are worth the price. The picture is Allen Tel model AT680, which is about as good as it gets. The ratchet mechanism ensures that you will get the connectors fully engaged before it lets you release.

Punch-down tool for 110-block

When attaching in-the-wall wiring to patch panels and wall-mounte jacks, the connector is usually of a type where the wire is squeezed into a slotted post, which pierces the insulation on the wire. The proper tool for this is a punch-down tool, which slides over the post and ensures that the wire gets to the bottom of the slot. There are two types of posts. The 110-type is used in wall jacks and in connector blocks used only for data.

Punch-down tool for 66-block

The 66-type connector block is the traditional cross-connect block used in telephone rooms, and has been extensively used for data as well. It is not as compact as the 110 connector block.

The 66 block has 50 rows, each with 4 slotted pins. For telephony, it is common to use a version where each row is broken in the middle, so that there are two sets of two posts each, which can be connected by a slip-on bridge clip. One punches the central office line down to the left side, then connects the PBX to the right side. Versions are available where one or both sides has a 50-pin amphenol connector that fits with a common 25-pair cable, allowing easy mass termination. Often, telephone switches bring their connections out on that type of connector.

http://www.cabletron.com/support/techtips/tk0231-9.html
http://www.combsnet.com/cable/Basics/basics.html 
  $Log: cat5wire.htm,v $
  Revision 1.6  2001/01/20 21:10:36  lars
  *** empty log message ***

  Revision 1.5  2000/09/08 00:38:16  lars
  Added GIF of RJ45 pin1 orientation.

  Revision 1.4  2000/08/15 01:31:24  lars
  Add link to FAQ.

  Revision 1.3  2000/06/21 05:09:58  lars
  Added cross-references, and supporting links.
  Added 25-pair color code.

  Revision 1.2  2000/05/27 00:22:32  lars
  Fix spelling errors, add plenum wire.

  Revision 1.1  2000/05/26 22:11:50  lars
  Added new page about cat5 wiring.