Optical Fiber CablesOptical Fiber Cables

Ch 4Ch 4

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

Jim HayesJim Hayes

Optical Fiber Cable Optical Fiber Cable ConstructionConstruction

Fiber and Acrylate CoatingFiber and Acrylate Coating

Optical fiber is covered Optical fiber is covered by an acrylate coating by an acrylate coating during manufactureduring manufacture• Coating protects the fiber Coating protects the fiber

from moisture and from moisture and mechanical damagemechanical damage

Three Cable TypesThree Cable Types

Tight-bufferTight-buffer Loose-tubeLoose-tube RibbonRibbon

Loose-Tube and Tight-BufferLoose-Tube and Tight-Buffer A A cablecable has: has:

• Optical fiber (core, cladding, and Optical fiber (core, cladding, and coating)coating)

• Buffer (loose or tight)Buffer (loose or tight)• Kevlar strength memberKevlar strength member• Outer JacketOuter Jacket

Image from commspecial.com (link Ch 4a)Image from commspecial.com (link Ch 4a)

Loose-Tube CableLoose-Tube Cable Used for long distances and outside-Used for long distances and outside-

plantplant Low attenuationLow attenuation Black jacketBlack jacket High pulling strengthHigh pulling strength

• Fibers are completely separated from Fibers are completely separated from environmentenvironment

• Image from alphawire.com (link Ch 4e)Image from alphawire.com (link Ch 4e)

Loose-Tube CableLoose-Tube Cable Tubes contain gel or absorbent tape Tubes contain gel or absorbent tape

to protect fibers from waterto protect fibers from water• Image from alphawire.com (link Ch 4e)Image from alphawire.com (link Ch 4e)

Loose-Tube CableLoose-Tube Cable Fibers must be Fibers must be

terminated with terminated with breakout kitsbreakout kits• Or fusion splicing Or fusion splicing

to pre-to pre-connectorized connectorized pigtailspigtails

• Image from Image from fonetworks.comfonetworks.com(link Ch 4d)(link Ch 4d)

Loose-Tube CableLoose-Tube Cable

Used OutdoorUsed Outdoor• Ducts or conduitsDucts or conduits• Aerial lashedAerial lashed• Directly buried Directly buried

(armored)(armored)

Weather-resistantWeather-resistant• From alphawire.com From alphawire.com

(link Ch 4k)(link Ch 4k)

Tight-Buffer Tight-Buffer CableCable

PVC Buffer is extruded directly onto the PVC Buffer is extruded directly onto the coatingcoating• Diameter is 900 micronsDiameter is 900 microns• Makes cable more flexibleMakes cable more flexible• Easier to terminateEasier to terminate• The most common indoor cable typeThe most common indoor cable type• Not good for outside useNot good for outside use

Because the buffer strains the fiber as temperature Because the buffer strains the fiber as temperature fluctuates, increasing attenuationfluctuates, increasing attenuation

Image from mohawk-cdt.com (link Ch 4f)Image from mohawk-cdt.com (link Ch 4f)

Distribution CablesDistribution Cables

Distribution CableDistribution Cable• Several tight-buffer Several tight-buffer

fibersfibers• Kevlar reinforcement Kevlar reinforcement

(Aramid)(Aramid)• One jacketOne jacket

Image from arcelect.com (link Ch 4g)Image from arcelect.com (link Ch 4g)

Distribution CableDistribution Cable Contains tight-buffered Contains tight-buffered

fibers in bundles of up fibers in bundles of up to 12 each to 12 each

Used for Riser and Used for Riser and Office CablingOffice Cabling

Must be terminated Must be terminated inside a patch panel or inside a patch panel or junction boxjunction box

• From alphawire.com (link Ch 4i)From alphawire.com (link Ch 4i)

Breakout CablesBreakout Cables

Breakout CableBreakout Cable• Reinforce each tight-buffer fiber with Reinforce each tight-buffer fiber with

Kevlar and jacket itKevlar and jacket it• Each fiber can be broken out and Each fiber can be broken out and

individually connectorizedindividually connectorized Image from arcelect.com (link Ch 4g)Image from arcelect.com (link Ch 4g)

Breakout CableBreakout Cable Several simplex units Several simplex units

cabled togethercabled together Stronger, larger and more Stronger, larger and more

expensive than distribution expensive than distribution cablescables

Used for Riser and Office Used for Riser and Office CablingCabling

Cables can be terminated Cables can be terminated individually and connected individually and connected directly to computersdirectly to computers• From alphawire.com (link Ch 4j)From alphawire.com (link Ch 4j)

Ribbon cableRibbon cable Dozens of fibers packed togetherDozens of fibers packed together Can be mass fusion spliced or mass Can be mass fusion spliced or mass

terminatedterminated

Images from gore.com (link Ch 4b) and alcatel.com (link Ch 4c)Images from gore.com (link Ch 4b) and alcatel.com (link Ch 4c)

Cable JacketingCable Jacketing

Chemical ResistanceChemical Resistance• Kynar, PFA, Teflon, Tefzel, or HalarKynar, PFA, Teflon, Tefzel, or Halar

AerospaceAerospace• Wide temperature range, ½ inch Wide temperature range, ½ inch

sustained bend radiussustained bend radius

Fire SafetyFire Safety Inside cable must meet National Electric Inside cable must meet National Electric

Code fire safety requirementsCode fire safety requirements• Horizontal Fire PropagationHorizontal Fire Propagation• Dripping of flaming materialDripping of flaming material

Irradiated Hypalon or XLPE meets these requirements Irradiated Hypalon or XLPE meets these requirements (plenum rated)(plenum rated)

Use of black outside-plant cable in Use of black outside-plant cable in buildings is limited to 50 feetbuildings is limited to 50 feet• See link Ch 4lSee link Ch 4l

Five Standard Cable TypesFive Standard Cable Types

Simplex and ZipcordSimplex and Zipcord DistributionDistribution BreakoutBreakout Loose-tubeLoose-tube Hybrid or CompositeHybrid or Composite

Simplex and ZipcordSimplex and Zipcord

Used For:Used For:• Patch CablesPatch Cables• Short Run Office Short Run Office

CablingCabling• Test EquipmentTest Equipment

From alphawire.comFrom alphawire.com (link Ch 4h) (link Ch 4h)

Hybrid or Composite CableHybrid or Composite Cable Hybrid cableHybrid cable

• Contains both singlemode and multimode Contains both singlemode and multimode fibersfibers

Composite cableComposite cable• Contains both copper wires and fiber Contains both copper wires and fiber

opticsoptics The two terms are often confusedThe two terms are often confused

Choice of CablesChoice of Cables

Choosing a CableChoosing a Cable

Cable Type Application Advantages

Tight Buffer Premises Makes rugged patch cords

Distribution Premises Small size for lots of fibers, inexpensive

Breakout PremisesRugged, easy to terminate, no hardware

needed

Loose TubeOutside

PlantRugged, gel or dry water-blocking

ArmoredOutside

PlantPrevents rodent damage

RibbonOutside

PlantHighest fiber count for small size

FromFrom lanshack.com (link Ch 4m)lanshack.com (link Ch 4m)

Factors to Consider when Factors to Consider when Choosing CableChoosing Cable

BandwidthBandwidth Attenuation & LengthAttenuation & Length CostCost Mechanical & UL/NEC RequirementsMechanical & UL/NEC Requirements Signal lossSignal loss ConnectorsConnectors Cable Dimensions & EnvironmentCable Dimensions & Environment Existing systemsExisting systems

Installing Fiber Optic CableInstalling Fiber Optic Cable Never pull on the fiber itselfNever pull on the fiber itself

• Pull only from the strength membersPull only from the strength members• Maximum pulling force 300 lb.Maximum pulling force 300 lb.

Never exceed bend radiusNever exceed bend radius• 10 x diameter without tension10 x diameter without tension• 20 x diameter under tension20 x diameter under tension

Images from Lennie Lightwave and bwcecom.belden.com Images from Lennie Lightwave and bwcecom.belden.com (Link Ch 4n)(Link Ch 4n)

Vertical InstallationsVertical Installations

Clamp the cable to distribute weight Clamp the cable to distribute weight evenlyevenly• Every 50 feet indoorsEvery 50 feet indoors• More often, up to every 3 feet, outdoorsMore often, up to every 3 feet, outdoors

Fiber migrates down, increasing Fiber migrates down, increasing attenuationattenuation• Place 1 foot loops at the top of the run, Place 1 foot loops at the top of the run,

bottom of run, and every 500 ft in bottom of run, and every 500 ft in betweenbetween

Pulling Cables through ConduitsPulling Cables through Conduits

Loose-buffer cables work bestLoose-buffer cables work best Video from American Polywater Video from American Polywater

(link Ch 4o)(link Ch 4o)

Direct BurialDirect Burial

Armor is desirable to protect the Armor is desirable to protect the cable from gophers, construction cable from gophers, construction digging, etc.digging, etc.

Gel filling is a water barrierGel filling is a water barrier

Aerial InstallationAerial Installation

Supported by Supported by messenger wire, ormessenger wire, or

Self-supportingSelf-supporting• Images of self-supporting cable Images of self-supporting cable

from ericsson.net and from ericsson.net and Arcelect.com (link Ch 4p & 4g)Arcelect.com (link Ch 4p & 4g)

OGW (Optical Ground OGW (Optical Ground Wire)Wire) cables carry both cables carry both electricity and fiber optic electricity and fiber optic signalssignals

Blown-in FiberBlown-in Fiber

Fiber is blown Fiber is blown through plastic tubes through plastic tubes with airwith air

Faster than pullingFaster than pulling• Image from fpnmag.com Image from fpnmag.com

(link Ch 4q(link Ch 4q))

Fire Code RatingsFire Code Ratings

NEC Rating Description

OFN Optical fiber non-conductive

OFC Optical fiber conductive

OFNG or OFCG General purpose

OFNR or OFCR Riser rated cable for vertical runs

OFNP or OFCPPlenum rated cables for use in air-

handling plenums

OFN-LS Low smoke density

See link Ch 4r for detailsSee link Ch 4r for details

NEC RequirementsNEC Requirements OFC cables have noncurrent-carrying OFC cables have noncurrent-carrying

conductive elementsconductive elements• Must be groundedMust be grounded• Cannot share a raceway with electric Cannot share a raceway with electric

power linespower lines• Can share with communications linesCan share with communications lines

Abandoned cables must be removedAbandoned cables must be removed