Installing the Cable Plant

10BaseT Wiring Notes
If you really want to tackle the job of wiring your office by yourself, we hope this helps. The information here is enough for you to maintain your cabling plant and add a few lines when needed. If you have more than a half-dozen lines, you may want to seek help. technotes@lpmedia.com

Terminology

AWG - American Wire Gauge, the standard measure for the diameter of a wire. As the numbers increase, the wire diameter decreases. Normal wire for 10BaseT is 22 or 24 AWG.
Conductors - A piece of wire. For 10BaseT purposes it is solid, copper wire. Don't use stranded, except for patch cords.

Crimper - A plier like device used to attach connectors to the end of cables.Steel Crimping Tool

Data Cable Levels - A cable grading scheme used by cable manufacturers to identify the designed transmission speed for a given cable. People will talk about Level 5 and Category 5 (Cat5). They mean the same

EMI/RFI - Electro-magnetic Interference / Radio Frequency Interference. The electrical signals in the air that you don't want in your cables. If someone tells you there is no EMI/RFI in their office building, just turn on a radio.

Hub - Also called a Concentrator. This is the central device in a 10BaseT network. Workstations are wired into its ports ( from 4 to 256 ) and the hub makes sure connections are good and passes the signals. Depending upon the level of sophistication and management, these can cost from $10 to $200 and up per port.

IBM Cable Types - IBM, of course, has its own method of defining cable types.

Impedance - An electrical characteristic that measures opposition to the flow of an alternating current in a wire. Just like resistance is to a direct current flow. AC signals get very upset when cables of different impedances are connected.

Link Beat - Once a second the Hub sends a signal to the workstation. If the workstation does not respond, the hub "segments" that workstation out of the net. This should prevent a bad cable or card from bringing down the whole network.

NEC - National Electric Code. NEC rates the cable for fire resistance and such. If you are going to run your cable above the ceiling in a space used for ventilation (a plenum), then you have to use plenum rated cable. This is a more expensive (Teflon sheath versus PVC) but is required to meet fire codes.

NIC - Network Interface Card.

Patch Cable - Usually a short cable, generally stranded to make it more manageable, Used to connect the wall plug to the workstations, or patch panel to hub, or patch panel to patch panel. Buy these pre-made, rather than build your own. Generally lengths from 1ft to 20ft.

Punch (down) Block - A device used in a central closet for managing wires. Available in a 66 or 110 model. The 110 is the new, electrically superior model, but the 66 seems to work fine. They have come up woth a Cat5 66 block! Wires are attached with a Punch (down) Tool. Punch Blocks are usually attached to the wall in a wiring closet or on a patch panel.

RJ-45 - A small plastic connector used on the end of a four pair cable. RJ-11 is the smaller one used for telephone connections.

Satin cable - Four/six/eight parallel wires (0 twists) used for telephone only. One comes with every modem. Not for network use.

STP - Shielded Twisted Pair. One or more twisted pairs inside an electrically conductive sheath (usually aluminum foil) that protects the pairs from outside interference. The shield should be grounded at the hub end. STP generally has an impedance of 150 ohms.

Twisted Pair - Two conductors that wrap around each other to form a pair.

UTP - Unshielded Twisted Pair. One or more twisted pairs inside an insulating sheath. UTP generally has an impedance of 100 ohms.


Cable Types RG-6 & Cat. 5E 350MHz Dual Cable

Cables are grouped in categories according to various factors. Levels specify a certain speed rating on the cable. IBM Cable Types specify a certain kind of cable. Please note that what is shown below is a very abbreviated description. Each Level or Type has specific physical and electrical characteristics and those details can be found in most cable vendors' catalogs. The number of twists per foot is at least two for data grade cable.

Data Grading Levels
These cables may be UTP or STP. The higher level cables have better conductors, insulation and more twists per foot.

Level 1- Used for up to 1 Megabit Per Second (Mps)
Level 2 - Used for up to 4 Mps
Level 3 - Used for up to 16 Mps
Level 4 - Used for up to 20 Mps
Level 5 - Used for up to 100 Mps
[AJ's note: There are some applications running 155 Mps on Cat5]

IBM Type Designations

Type 1 - Two pair of 22 AWG, each pair foil wrapped inside another foil sheath that has a wire braid ground. This is usually what most people think of as "STP".
Type 2 - Type 1 with 4 telephone pair sheathed to the outside to allow one cable to an office for both voice and data.
Type 3 - Four pair of unshielded 22 or 24 AWG, each pair wrapped at least twice per foot. This is what most people think of as "UTP"
Type 4 - There isn't one!
Type 5 - Fiber optic
Type 6 - Two pair of stranded, shielded 26 AWG to be used for patch cables.
Type 7 - One pair of stranded, 26 AWG wire.
Type 8 - Two parallel pairs (flat wires with no twist) of 26 AWG used for undercarpet installation.
Type 9 - Two pair of shielded 26 AWG used for data. Doesn't carry data as well as Type 1 due to smaller conductors.

Cable Planning


Wiring should be run from each workstation (or node) back to a central wiring closet. Hubs can be connected by UTP thru the ports with a cross over cable, by coax thru the BNC connector or thru fiber.


Maximum from hub to workstation is 100 meters.
Maximum distance from hub to hub using UTP is 100 meters.
Maximum distance from hub to hub using RG-58 coax is 185 meters.
Minumum distance from hub to hub using RG-58 coax is .5 meters.
Maximum number of punch blocks or patch panels (i.e. breaks in the cable) is 4.
Maximum number of devices on an RG-58 coax cable segment is 30.
Maximum number of cascaded hubs is 4. In other words, from one node to any other the signal cannot pass thru more than 4 hubs.

 

 

Data Twist 350 Cat 5E

 

Wiring Diagrams

Important Note - The RJ-45 is the key to the whole system. The NIC and Hub must have the cables done in a certain way in order to work. The punch blocks, patch panels, etc, really don't matter as long as the wire continues correctly from end to end. HOWEVER, do yourself an enormous favor and do your wiring consistent with industry standards.  Its much easier to troubleshoot a job you completed last year if you've installed the cable correctly.

Four pair wire is the standard with Pair 1 as Blue, Pair 2 as Orange, Pair 3 as Green and Pair 4 as Brown. Colors are always shown with the Base Color first, then the Stripe Color. The RJ-45 is wired as follows:

 

Pin 1 White/Orange Transmit -
Pin 2 Orange/White Transmit +
Pin 3 White/Green Receive -
Pin 4 Blue/White
Pin 5 White/Blue
Pin 6 Green/White Receive +
Pin 7 White/Brown
Pin 8 Brown/White

 

Two notes - First, holding the cable in your left hand, with the RJ-45 pins facing up, Pin 1 is the furthest away from you. Second, the blue and brown pair are unused and there is a big discussion on whether you can use them or not. The feeling seems to be that digital telephone is OK, but analog telephone (modem, fax) is not due to the high ring voltage. I am running dual ports so that I use all 4 pair and get two computer connected to the LAN, using the extra two pairs as another connection.

To make a Cross Over patch cable for hub to hub connections or connecting just two computers together, wire the ends as follows: