Fiber Optic Cable PullingFiber Optic Cable Pulling

Ch 15Ch 15

Fiber Optics Technician’s Fiber Optics Technician’s Manual, 3Manual, 3rdrd. Ed. Ed

Jim HayesJim Hayes

Last modified 11-17-08

Avoiding DisasterAvoiding Disaster

Tensile stress (pulling load)Tensile stress (pulling load) Bending radiusBending radius

Despooling CableDespooling Cable

Pull the cable to the side, not over Pull the cable to the side, not over the top of the reelthe top of the reel• Pull only from the strength memberPull only from the strength member• Avoids excessive force on the cableAvoids excessive force on the cable

That would stretch the jacket and cause That would stretch the jacket and cause fiber compression when the tension is fiber compression when the tension is releasedreleased

Produces macrobends and attenuationProduces macrobends and attenuation

• Also avoids twists in the cableAlso avoids twists in the cable

Microbends Microbends (not in textbook)(not in textbook)

Microscopic bends in the fiber that occur mainly when the fiber is cabled.

Causes loss• See links

Ch_15a, Ch_15b

Microbends Microbends (not in textbook)(not in textbook)

Sources of stress can create microbends, such as:• Irregularities during fiber manufacturing• Manipulation of the fiber during cable

manufacturing• Installation operations and equipment

(tie wraps, clamps)• Environmental stresses (pressure, hits)

MacrobendsMacrobends

Bending the cable too tightly, but Bending the cable too tightly, but through a radius larger than the fiber through a radius larger than the fiber diameterdiameter

During pull – no less than 20 During pull – no less than 20 diametersdiameters• Otherwise you can damage the cableOtherwise you can damage the cable

Static – no less than 10 diametersStatic – no less than 10 diameters• Causes lossCauses loss

Pulling ForcePulling Force

Usually 600 lb. for outside plant Usually 600 lb. for outside plant cablecable

300 lb or less for indoor cable300 lb or less for indoor cable Must not be exceededMust not be exceeded Pull should be smooth, not jerkyPull should be smooth, not jerky Pull on strength member onlyPull on strength member only

Test Cable Before PullingTest Cable Before Pulling

Avoids quality problems and finger-Avoids quality problems and finger-pointing after installationpointing after installation

Continuity is often enoughContinuity is often enough• Does it transmit light?Does it transmit light?• Images fromImages from

link Ch 15clink Ch 15c

Interference from Other Interference from Other Installations Installations

Ways to protect the fiber:Ways to protect the fiber:• Put it under other cables in ductPut it under other cables in duct• Put fiber in last, on topPut fiber in last, on top• Be careful about sharp edges in ductBe careful about sharp edges in duct

Use innerductUse innerduct

Procedures for Pulling CableProcedures for Pulling Cable Do long pulls from the Do long pulls from the

middlemiddle Do very long pulls in Do very long pulls in

stages with figure-8sstages with figure-8s Two ways to attach rope:Two ways to attach rope:

• Direct attachment to Direct attachment to strength memberstrength member

• Kellems grip to grab whole Kellems grip to grab whole cable from outsidecable from outside

• Or both at onceOr both at once Images from link Ch 15dImages from link Ch 15d

Using the Kellems GripUsing the Kellems Grip

Corning recommends using both the Corning recommends using both the strength member and a Kellems grip strength member and a Kellems grip to distribute tensionto distribute tension

Cover the grip with vinyl tapeCover the grip with vinyl tape• See link Ch 15eSee link Ch 15e

Puller Works Like a CapstanPuller Works Like a Capstan

From Link Ch 15fFrom Link Ch 15f

LubricantLubricant

Use lubricant designed for the cableUse lubricant designed for the cable Avoid lubricating the part of the Avoid lubricating the part of the

cable that will be handledcable that will be handled

Pull SpeedPull Speed

Max. speed 2 mph when using ropeMax. speed 2 mph when using rope You can pull 3 x as fast with You can pull 3 x as fast with

measurement/pull tape than with measurement/pull tape than with rope because the rope cuts grooves rope because the rope cuts grooves in conduitin conduit

Image from Image from arncocorp.com arncocorp.com (Link Ch 11f) (Link Ch 11f)

Racking and LabellingRacking and Labelling

““Rack” cable – lash it to the sides of Rack” cable – lash it to the sides of a manhole or pull box with cable tiesa manhole or pull box with cable ties

Attach cable ID tags anywhere Attach cable ID tags anywhere people might see the cablepeople might see the cable• State fiber core size, where it is State fiber core size, where it is

accessible on both ends, and who the accessible on both ends, and who the owner isowner is

Premises CablesPremises Cables

They are more fragile than outdoor They are more fragile than outdoor cablescables• Avoid kinks and snagsAvoid kinks and snags

Heavy copper cables can put Heavy copper cables can put pressure on fiber sharing the same pressure on fiber sharing the same traystrays• One solution is innerductOne solution is innerduct• Innerduct with pull tape already Innerduct with pull tape already

installed is very easy to installinstalled is very easy to install

Premises CablesPremises Cables

Use cables with proper fire ratingsUse cables with proper fire ratings Remove old cablesRemove old cables Leave service loops – extra lengthLeave service loops – extra length

Fiber Optic RestorationFiber Optic Restoration

Ch 16Ch 16

Fiber Optics Technician’s Fiber Optics Technician’s Manual, 3Manual, 3rdrd. Ed. Ed

Jim HayesJim Hayes

Proactive PlanningProactive Planning

Designing a Designing a network that is network that is reliablereliable

FDDI is reliable FDDI is reliable because it uses because it uses two counter-two counter-rotating ringsrotating rings

““self-healing”self-healing”

Route DiversityRoute Diversity

More than one path for the dataMore than one path for the data No single point of failureNo single point of failure Increases network cost, but also Increases network cost, but also

increases reliabilityincreases reliability

Faults at the Patch PanelFaults at the Patch Panel

Improper dressing of jumpers and Improper dressing of jumpers and cablescables• Dressing the cable involves properly Dressing the cable involves properly

aligning and positioning the cables in a aligning and positioning the cables in a neat and orderly manner for terminationneat and orderly manner for termination

From Link Ch 16a From Link Ch 16a

Well-dressed Patch PanelWell-dressed Patch Panel

From link Ch 16hFrom link Ch 16h

Messy NetworksMessy Networks

See more at link Ch 16iSee more at link Ch 16i

Faults at the Patch PanelFaults at the Patch Panel

Improper keying or dirty connectorsImproper keying or dirty connectors Local damageLocal damage

Faults of System Faults of System

Under- or over-driving the optical Under- or over-driving the optical transmission causes problemstransmission causes problems• On LANs, under-driving is more likely On LANs, under-driving is more likely

(too many dB of loss)(too many dB of loss)• Some high-power laser sources can Some high-power laser sources can

saturate the receiver if the network has saturate the receiver if the network has too little losstoo little loss

Faults from InstallationFaults from Installation

Improper bend radiusImproper bend radius Clamping too tightClamping too tight Dressing, termination, routingDressing, termination, routing

Faults from ConstructionFaults from Construction

Backhoes digging up cableBackhoes digging up cable Aerial cables falling downAerial cables falling down

• Lightning, falling trees, etc.Lightning, falling trees, etc. Cutting through walls or ceilings in Cutting through walls or ceilings in

LANsLANs

Typical Cable System Faults

Equipment Used in RestorationEquipment Used in Restoration

Cleaning kitCleaning kit MicroscopeMicroscope Light source and power meterLight source and power meter Visual Fault LocatorVisual Fault Locator

• Bright laser VFLs are best for finding internal Bright laser VFLs are best for finding internal breaksbreaks

OTDROTDR• Essential for outside plant work to locate faultsEssential for outside plant work to locate faults• Less common for LANsLess common for LANs

High cost High cost Short networksShort networks

Restoration Restoration Flow ChartFlow Chart

First test First test power to power to receiverreceiver

Then power Then power from from transmittertransmitter

That will That will determine if determine if the problem is the problem is in the in the electronics or electronics or the fiberthe fiber

Locating a Cable Plant ProblemLocating a Cable Plant Problem

Use a VFL to locate the problemUse a VFL to locate the problem• Sometimes you will see the red light Sometimes you will see the red light

escaping at a break or bad connectionescaping at a break or bad connection• You can also just see how far down the You can also just see how far down the

cable plant the red light goes before it cable plant the red light goes before it stopsstops

For longer runs, good documentation For longer runs, good documentation is extremely important so you can is extremely important so you can follow the cable routefollow the cable route

OTDROTDR

If a cable is over 500 m or If a cable is over 500 m or underground, an OTDR may be underground, an OTDR may be necessarynecessary

Use a launch cable to eliminate the Use a launch cable to eliminate the end zoneend zone

Use the 850-nm range to get best Use the 850-nm range to get best distance resolutiondistance resolution

Restoring ServiceRestoring Service

Protect repair points with closures or Protect repair points with closures or patch panelspatch panels• New hardware may be neededNew hardware may be needed

Can the system handle the added Can the system handle the added loss of the new connectors, splices, loss of the new connectors, splices, and cable length?and cable length?

Can you run a temporary span of Can you run a temporary span of cable through the ceiling, over the cable through the ceiling, over the roof, etc. to restore service quickly?roof, etc. to restore service quickly?

Storage LoopsStorage Loops

Buildings change a lot, so do Buildings change a lot, so do networksnetworks

Slack should be stored on the wall or Slack should be stored on the wall or ceiling, considering aesthetics and ceiling, considering aesthetics and sizesize

Emergency Restoration Emergency Restoration (With Retrievable Slack)(With Retrievable Slack)

Use a VFL to find the breakUse a VFL to find the break• Test from both ends to make sure there Test from both ends to make sure there

is only one breakis only one break Choose best point and method to Choose best point and method to

repair fiberrepair fiber• Pull cables back to ceiling, floor, post Pull cables back to ceiling, floor, post

etc. for physical mountingetc. for physical mounting Document RepairDocument Repair Test the repaired spanTest the repaired span

Emergency RestorationEmergency Restoration(No Retrievable Slack)(No Retrievable Slack)

Would it be quicker to pull in a new Would it be quicker to pull in a new cable or segment?cable or segment?

To repair, you must add in more To repair, you must add in more cablecable• Two termination points, double the labor Two termination points, double the labor

and materialand material• New cable must have at least as many New cable must have at least as many

fibers as the existing cablefibers as the existing cable

Restoration for Singlemode Restoration for Singlemode NetworksNetworks

More difficult to repair than More difficult to repair than multimode networksmultimode networks• Higher speeds and greater distancesHigher speeds and greater distances• Cable is often buried, aerial-placed, or in Cable is often buried, aerial-placed, or in

long conduitlong conduit• Problem often caused by a natural Problem often caused by a natural

disaster or construction workdisaster or construction work• Many users are affected, large revenue Many users are affected, large revenue

losseslosses

Singlemode Restoration Singlemode Restoration SuggestionsSuggestions

Prioritize fibers – then fix most Prioritize fibers – then fix most important fibers firstimportant fibers first

Have a kit ready with spare Have a kit ready with spare connectors, connectorization kit, connectors, connectorization kit, mechanical splicesmechanical splices

Have a trained restoration crew with Have a trained restoration crew with emergency phone numbersemergency phone numbers

Have test equipment and tools readyHave test equipment and tools ready

Restoring ServiceRestoring Service

A single broken fiber can be replaced A single broken fiber can be replaced using a dark fiber (if one is available)using a dark fiber (if one is available)

Is there enough slack to make a Is there enough slack to make a repair point?repair point?

Would replacing the span be easier, Would replacing the span be easier, quicker, cheaper than repairing it?quicker, cheaper than repairing it?

Install connectors or splice?Install connectors or splice?

Recommended Restoration Posture

Document fiber routes• Patch panel designations, signal type, interconnect

routing

Document transmitters’ and receivers’ power levels• Both minimum and maximum power for detectors

Document optical loss for all spans• At both wavelengths (850/1300 nm for multimode and

1310/1550 nm for singlemode)

Document fiber size and manufacturer

Recommended Restoration Posture

Copies of OTDR traces (if any) Document actual cable length in

meters or feet for each segment from cable markings

Prioritize fibers

Restoration PlanningRestoration Planning

Flow of information – who detects the problem, and who do they call?

Is an emergency restoration needed, or can we do a planned restoration

Make sure you have records, kits, trsined staff

Prioritize your customer and fibers

Restoration PlanningRestoration Planning

What is the time allowance for restoration?

Temporary or permanent repair? How much loss is tolerable?

Arrange for communications between OTDR operators and splicers

Restoration (Misc.)Restoration (Misc.)

Keep the restoration plan and staff current Test existing dark fibers regularly Evaluate each cable segment for worst

case failures Do you photograph/film your restorations?

The use of film and/or pictures provides a good learning and review tool. In the case of litigation the pictures can be invaluable.

PostrestorationPostrestoration Redocument and retest your splices,

spans, and segments. Adjust your “as built” drawings Have a meeting to review all aspects of

the restoration.• What happened? What were the cause and

impacts?• What did we do well?• What did not work? (Technique, equipment,

products, staff)• How can this be resolved?• How can we improve?• What needs to be done to rebuild kits and

replenish inventory?

Color Codes (not in textbook)Color Codes (not in textbook)

For loose-tube cables, For loose-tube cables, both the individual fibers both the individual fibers and the buffer tubes are and the buffer tubes are color-codedcolor-coded

TIA/EIA-598 Color CodeTIA/EIA-598 Color Code

Position Color

1 Blue

2 Orange

3 Green

4 Brown

5 Slate

6 White

7 Red

8 Black

9 Yellow

10 Violet

11 Rose

12 Aqua

Cable Jacket Colors (not in Cable Jacket Colors (not in textbook)textbook)

Cable jackets also have a color code, Cable jackets also have a color code, although not all manufacturers obey although not all manufacturers obey itit

Multimode indoor cable: orangeMultimode indoor cable: orange Singlemode indoor cable: yellowSinglemode indoor cable: yellow Outdoor cable: black Outdoor cable: black Laser-optimized: aquaLaser-optimized: aqua

• See links Ch 16c, Ch 16dSee links Ch 16c, Ch 16d