Structured Cabling Project

Chapter 9

By: Nisreen Otaky

Safety is primary concern Never work on a device with the case open and the

power plugged in. Test electrical sockets with a multimeter Locate all electrical conduits and power wires before

installing any cables Properly ground all networking equipment. Never cut or

nick a live 120V AC line. Wear safety glasses whenever you are drilling or cutting Measure carefully before you cut, drill into, or

permanently alter construction materials. Investigate what you will be drilling or cutting into,

before you begin Cleanliness ex. minimize the amount of dust Follow proper ladder placement and safety procedures

whenever you must use a ladder

Network DocumentationSome of the documents you should create

while planning/designing your network:engineering journal: logical topology physical topology cut sheets: a rough sketch of cabling runsproblem-solving matrices labeled outlets labeled cable runs summary of outlets and cable runs summary of devices, MAC addresses, and IP

addresses

Project Planning Structured cabling project is ideal for group

work so assign different group members different jobs

Ex: Cable runner, project manager , Jack and Patch Panel Terminator

Create a flowchart to insure project is done thoroughly, accurately and on time

installing outlets, jacks running cables and testing them punching cables into patch panels documenting cables installing PCs, NICs, hubs, switches, routers configuring PCs, switches, routers

TIA/EIA-568-A standards

3m6m

90m

RJ-45 JackOne side of the RJ-45 jack contains eight

color-coded slots. The individual Cat5 wires are punched down into the slots according to color using a punch down tool. The other side of the jack is a female plug, which looks like a standard phone jack

There are 2 methods for mounting RJ-45 jacksSurface mounting: mount the jacks on the

surface of the wallFlush mounting: cut through the wall

Surface-mounting an RJ-45 jackTwo types of boxes that you can use to surface

mount RJ-45 jacks to a wallScrew-mounted boxAdhesive-backed box

Adhesive-backed are faster to install; however once affixed, you can’t move them

Most network installers prefer to use surface-mounted RJ-45 jacks because they are easier and faster to install. You don’t need to cut into the wall

Details on how to surface-mount an RJ-45 jack are found in Chapter 9.2.4

Flush Mounting an RJ-45 jackYou must take several factors into

consideration before you decide to flush mount an RJ-45 jack into a wall. Is the wall made of plaster or drywall?

Plaster is harder to work with because it crumbles easily

Are there any wide wood baseboards on the wall? if so you may want to install the jack there. But make sure you don’t cut the opening into the bottom 5 cm of the baseboard, because the walls bottom plate will block you from pushing it in

Details on flush-mounting RJ-45 jacks are found in Chapter 9.2

Procedure for placing the copper wires in a jack

Steps you must use to place the cable wires into the jack:Strip the jacket about 2.5 cmPlace the wires in front of the jack and keep

them there while you workSeparate each pair of twisted wiresPlace each wire on the corresponding color-

coded slot of the jackPunch the wires down into the slots using a

punch down tool

Procedure for punching copper wires in a jack

A punch tool is a device that uses spring-loaded action to push wires between the pins on the jack while at the same time, skinning the sheath away from the wire.

Basics for Installing Strip back only as much of the cable's jacket as is required to

terminate the wires Make sure that you maintain the twists in each pair of wires, as

much as possible. It is the twisting of the wires that produces the cancellation that is needed to prevent EMI and RFI. CAT 5 UTP, the maximum amount of untwisted wire that is allowed is 13 mm

Never bend cable to the extent that it exceeds a 90º angle Avoid stretching cable when you are handling it, wires inside

will untwist If multiple cables must run over the same path, use cable ties to

cinch them together. Never allow cables to be nicked or kinked Leave enough slack for the cable to reach the floor, and extend

another 60-90 cm at both ends. Use cable ties, cable support bars, wire management panels, and

releasable Velcro straps to secure cables. Never use a staple gun

Do’s and Don’ts for UTP

Do’s Don’tsUse Cable Ties Don’t untwist wires

more than 13mm

Leave Slack Minimize the bent radius to 90º

Leave Service coils in the ceiling

No Kinks

Use support bars Don’t stretch the cable

Use Velcro Minimize twisting the cable jackets

Use Cable Management Panels

No staple guns

Documenting cable runsA cut sheet is a rough diagram that:

Shows the locations of the cable runs Indicates the numbers of the classrooms,

offices, or other rooms, to which the cables have been run.Ex. Rm# 519, 201

Can be referred to when its time to place corresponding numbers on all telecom outlets and patch panels in the wiring closet

Specifications for labeling cable

According to the TIA/EIA 606 standards, each hardware termination unit must have some kind of unique identifier. This identifier must be marked on each termination hardware unit. Termination hardware units include:Patch panelsJacksComputerAlso important to label the cable at each end

Specifications for labeling cableFor example, if you have 4 cables going to

room number 201:Label each cable as 201A, 201B, 201C, 201DLabel each faceplate going to the particular

workstation with the same number i.e. 201AAlso label each cable connection at the patch

panel in the wiring closet in ascending order

Preparing cable for routing and labeling

If you need to route 4 cables to each room, route all four cables at the same time

Use 4 spools of cableAssign a letter to each spool

Ex. A for the cable going to room A  Place the spools at the central point or wiring

closet. Unwind a segment of the cable and label it 3 times,

each label being 60 cm apartEx. 201A, 201B

Use electrical tape to keep all 4 cables together while routing them

Tie a string around the ends to help pull the cables

Easiest procedure for routing cable

The easiest way to route cable is to mount it on a wallTie the cables with a tie-wrap then mount the

tie-wrap to the wall.You can use screws to put the tie-wrap on the

wallOr adhesive tie-wraps if you’re sure that the

cables will not need to be moved

Never use staples to attach cable to walls

Mounting cable in racewayRaceway is a wall-mounted channel that has a

removable coverdecorative raceway

presents a more finished appearance Placed in areas where the raceway may be seen

gutter raceway less attractive alternative to decorative raceway primary advantage is that it is big enough to hold several

cables restricted to spaces such as attics and spaces created by

dropped ceilings.   

Can be mounted with adhesive backing or with screws

After mounting the raceway, lay the cable inside it, and attach the top.

This will help to protect the cable

Running cable through existing raceway

Two concerns with routing cable in existing raceway: First, is there room? The new bundle of

cable you want to route in the raceway may exceed the capacity of the raceway.

Second, it is preferable not to route cable in a raceway with power wiring. This can potentially cause noise problems.

Personal safety precautions before installing cable

When working in walls, ceilings or attics, turn off all power that might pass through that area

Before you begin work, learn the locations of all fire extinguishers

Avoid wearing excessively baggy clothesIf you anticipate working in a dropped ceiling

space, survey the areaIf you need to cut or saw, wear safety glassesConsult the building’s maintenance engineer to

find out if there is asbestos or lead where you’ll be working

Keep your work area orderly and neat

Building safetyAlways find out in advance what the local

building codes are. Some building codes may prohibit

drilling or cutting holes in certain areas such as fire walls or ceilings

If you must route cable through spaces where air is circulated, you will need to use a fire-rated cable.

Supporting horizontal cablingWhen running cable in a dropped ceiling

space, never lay the cable on top of the ceiling. Use:Wall-mounted gutterUse tie-wraps Ladder racks

Stringing cable in an attic, or room with a dropped ceiling

A telepole is a telescoping pole with a hook at one end to hold the cable. It is used to string cable across a dropped ceiling or attic quickly.

Used in areas where it’s cramped, dark, dusty, and there’s poor air circulation

Fishing cable from above a wall When you fish cable through a wall you

ordinarily work from an attic or a dropped ceiling space.

Locate the top plate of the wall, and drill a 19 mm hole through it.

feed fish tape through the hole you drilled, down into the wall

Your helper below you should grab the tape when he sees it

Then he should tape the UTP cable to the hook of the fish tape

Then you can pull the cable up through the wall

Fishing cable from below a wall You can fish horizontal cable from a basement to

the work areas on the first floor Drill a 3.2 mm hole, at an angle, through the first

floor Push a coat hanger into the hole to indicate the spot

when you are in the basement. Go to the basement and locate the wire. Mark the spot Drill a new hole in this spot Push the cable up through this second hole, to the

wall opening where the work area outlet is located

Wiring ClosetA wiring closet can either be a specially

designed room or cabinet. Equipment in a wiring closet include: Patch PanelsWiring HubsBridgesSwitchesRouters

When you have more than one wiring closet in a network, one closet is designated as the MDF and all the others are IDFs

Patch PanelsA patch panel is an interconnecting

device that acts as a switchboard, where horizontal cables coming from workstations, can connect to other networking devices to form a LAN

The front of a patch panel resemble the ports on faceplates of telecomm outlets in the work area.

The back of a patch panel rows of pins, much like those in an RJ-45 jack

Laying wires in a patch panel Lay down cable wires in ascending

order, by cable number. Keep the ends of the cable centered

above the pin locations Keep the jacket within 6.4 mm of the

pin locations in order to avoid exposing too much wire.

Don’t untwist the wire pairs any more than necessary

Punch ToolsA punch tool has spring-loaded actions.

This allows it to perform 3 functions:

Pushes the wire between two metal pinsSkins the sheath from the wire (so that it can

make an electrical connection with the pins) The punch tool's blade also cuts off any

extra wire.

Mounting a patch panelYou can mount patch panels:

On wallsOn distribution racksIn a cabinet

A distribution rack is a simple skeletal frame that holds equipment such as patch panels, repeaters, hubs, and routers. Advantage is that it allows easy access to the

front and the back of equipmentHeight 1-1.9mWidth 0.5m

Network Operation TestingThe baseline is the set of data about your

network:Taken when network is operating at an

acceptable level Used to compare current measurements with

the recorded measurements that were taken when the system was known to be operating properly

Cable testing equipmentA cable tester is a hand held device that

can certify that cable meets the required IEEE and TIA/EIA standards

Some can provide printouts, others can be attached to a PC to create a data file.

Tests performed by cable testersdetermine cable distance locate bad connections provide wire maps for detecting crossed

pairs measure signal attenuation measure near-end crosstalk  detect split pairs  perform noise level tests  trace cable behind walls 

Cable testers and distance measurements

Time domain reflectometers (TDRs), measure the distance to open-ended, or shorted, cable They do it by sending an electrical pulse

through the cable Device then times the signal's reflection

from the end of the cable. Accurate to within 60 cm

Time Domain Reflectometers In order for it to determine which

connections in a cable run are faulty,Attach the TDR to the patch cord at the

patch panelIf it reports the distance to the patch panel,

instead of a more distance point, then you know there is a connection problem at that level

Then you can measure through the RJ-45 jack located at the telecomm outlet. If it reports the distance to the patch panel,

instead of a more distance point, then you know there is a connection problem at that level

Wire MapsWhen wires are connected in reversed

order, they are referred to as crossed pairs

The connections are not good, and must be redone

A wire map indicates which wire pairs connect to which pins and detects crossed-pairs

Causes crosstalk

Crossed PairsA crossed pair would be taking 1 and putting it in 2 on the other end. This is correct wiring

Split pairs

When wires split, they are no longer part of the same circuit

Therefore they provide no cancellation; no protection

Resulting in crosstalkDetected by visual inspection and

crosstalk measurements

Split pairs

Pairs are supposed to be 1-2 and 3-6

Signal Attenuation

A reduction in the power of a signal is called attenuation

A signal injector sends out a signal onto the cable which is attached on the other end to a cable tester

Sources of noise

florescent lights heaters radios televisions computers motion sensors radar motors electronic devices of all kinds

Crosstalk

SummaryCauses of crosstalk include:

Split pairsCrossed pairsCable pulled too tightlyUntwisted too much at the patch panelOutside interference