Chapter 13: Wiring Plans and Equipment Rooms

Overview

This chapter covers structured wiring and methods of routing it from equipment rooms to desktops. It also discusses types of wire and cable, equipment rooms and telecommunications pathways and standards, as well as vendor selection considerations. Planning is key to any successful equipment room and wiring arrangement. Future rearrangements can be expensive and difficult. Plan for facilities, but always remember that records management is very important too. A good cable management system can help and save time and money in the future years to come.

Background

·        Before wiring standards were set, wiring was chaotic
·        Wire standards were set in the 1990s by two associations:
·        The Electronic Industry Association (EIA), and
·        The Telecommunications Industry Association (TIA)

Wiring Media

Three types of wiring media: 1) Twisted-pair wire, 2) Coaxial Cable, 3) Fiber Optics

Twisted Pair

·        Consists of multiple wire pairs tightly and uniformly twisted around other pairs to ensure each wire has equal exposure to every other wire in the cable
·        Preferred medium for all but highest-speed applications. Comes in two varieties: 1) Shielded (STP) 2) Unshielded (UTP)
·        UTP preferred and used for all voice applications, nearly all data and LAN applications and becoming significant for video applications
·        Standards organizations: EIA (The Electronic Industry. Assoc.) and TIA (Telecom. Industry Assoc.) divided wire into 5 categories (3, 4, 5 most common). Categories 6 & 7 currently being considered
·        Advantages: Inexpensive, compact, easy to install
·        Disadvantages: Susceptible to interference, narrow bandwidth (limiting data transmission over long distances)

Unshielded Twisted Pair Wire Characteristics

Coaxial Cable

·        Used to connecting terminals to host computers and controllers, also used for video transmission 
·        Thin Coax: Consists of single center conductor, surrounded by insulating medium and covered with braided shield
·        Advantages/Disadvantages—Thin Coax: Inexpensive, flexible, easy to install, but less suitable over long distances
·        Rigid Coax: Constructed with discs of insulating material spaced at 6” intervals, enclosed in rigid copper or aluminum tube 
·        Advantages/Disadvantages—Rigid Coax: Suitable over longer distances, but more difficult to install and terminate

Fiber Optics

·        Consists of tiny strands of highly transparent glass that guides light pulses. Comes in variety of sizes and sheath composition. Single-mode and multimode available. Single-mode normally used for longer carrier applications. Most applications require multimode fiber
·        Good idea to always extend both kinds of fiber into backbone—to “future proof” the system
·        Limited application in wiring to desktop now, but use growing as price drops 
·        Advantages: High bandwidth and immune to electromagnet induction (cannot be tapped easily), but more expensive and difficult to install than other media and limits application to point-to-point use and LANS with star topology

Wiring Standards

·        Set by EIA and TIA, known as EIA/TIA 568 standards. (Very complex). Purpose: to specify a generic wiring standard independent of manufacturer’s
·        Sets transmission performance levels, technical criteria—from resistance to crosstalk/interference requirements

Covers 6 areas:

1.      Entrance facilities, discusses how cabling enters the building
2.      Backbone facilities, also known as “riser cable” covers both intrabuilding and interbuilding backbone facilities
3.      Equipment rooms, contain PBX and data equipment
4.      Telecommunication closets (TC), contains junction between backbone cable and horizontal wiring
5.      Horizontal wiring, extends from the TC to the work area
6.      Work areas, areas that are occupied by the user

Wiring Systems

·        Wiring Systems consist of: wire, connector at head, jack/outlet at station end
·        Channel: patch cords or jumper wires (used to connect wire to station apparatus & hubs)
·        Quality of data transmission medium measured by error rate and bandwidth. (Bandwidth inversely proportional to distance). EIA/TIA specifies max. channel length also interference limits
·        Sources of interference: radiation from other sources, surge currents, cross-talk (which is greatest at ends of circuit and can be controlled by tight control of cable twist during manufacture)
·        Every building has: 1) Equipment room, 2) Telecommunications closets (one or more--unlimited)
·        Grounding: Many problems traced to grounding. Grounding bus connected to main power ground, extends through riser system and if there is more than one TC on ea. Floor, separate grounding riser routed to ea. Closet. Grounding bus also attached to building’s structural steel system

Building Entrance Cabling:

·        Conduit Entrances: Preferred by builder and LEC—because of flexibility and service protection. Has aesthetic advantages, offers best mechanical protection, facilitates expansion. (*Communication and power cables can not share conduit, however twisted pair wire, coaxial and fiber-optic cable can share same conduit, if dimensions permit). Conduit should be 4” in diameter and non-corrosive material

·        Direct Burial: Less expensive as long as future additions/changes not expected Not as well protected as conduit. Cable placed in trench or put to depth of 2’ 

·        Aerial: Seen mainly in suburban or rural areas and is advantageous within plants to interconnect buildings. Less expensive than other methods, but is unattractive and susceptible to damage

·        Entrance Cable Termination: Usually, LEC owns entrance cable and carries it to point of connection with building (the agreed upon point of demarcation) 

·        Electrical Protection: All entrance cables must be protected from electrical hazards Protection consists of: 1) High current, 2) Over voltage. Protection usually in form of heat coils. LEC responsible for protecting circuits potentially exposed to high voltage, whereas users responsible for protection in inter-building cables

·        Equipment Rooms: Requirements depend on equipment. (Large PBX systems, for example, require special rooms, ventilation, etc.). Considerations include:

·        Security—

·        Floor space considerations—(If equipment selected before space planned, take manufacturer’s recommendations on space requirements. Add space for auxiliary equipment. Room must be wired with enough power and if battery backup included, place in a separate room

·        Location—9 considerations: 1) Centralization, 2) Security, 3) Hazards, 4) Accessibility, 5) Fire suppression, 6) Wall space, 7) Environmental considerations, 8) Storage space, 9) Lighting

·        Main Distributing Frames: Should be employed in every telecommunications system. First point of cross-connection is in the equipment room. Terminated here are: outside cables from LECS, intra-building and inter-building backbone cables and cables to equipment located in the same room. (*Complete cable system records should be maintained on paper or in a database mgmt. system. Cable management systems available on the market)

·        Backbone Cable: Often called riser cable even though it may be horizontal. (Building risers connect between floors, campus riders between buildings) 

·        Intra-Building Risers connect equipment room to telecommunications closets on each floor

·        Inter-Building Services outlying buildings. Installation similar to entrance cables (encased in conduit, placed in trench, or suspended between poles)

·        Intermediate Distributing Frame: Consists of connector blocks—where one set terminates the backbone cable and other set terminates horizontal distribution wires to stations 

·        Horizontal Wiring System: Connecting TC and Work Area Outlets—Most complex part is cabling between Telecommunications Closet and Work Areas. (Usually a matter of making compromises). Considerations:

·        Exposed Wiring—least costly, very unattractive, found mainly in factories, warehouses, etc.

·        Conduit is excellent method of cabling—usually practical for new construction or during remodeling. Makes wiring installation easier and allows for need deferment; however, it is costly, and less flexibility than other methods

·        Poke-Through—used widely in residences and small-frame businesses and in multistory structures with suspended ceilings. Method is reasonably flexible

·        Cellular Floors—similar to poke-through except steel or concrete cells are embedded in floor. Alternate cells contain power and communication wiring  (Advantages- adds to structural strength of building and offers high security and protection from electromagnetic interference)

·        Suspended Ceiling—routed through fixed or portable walls or through metal “telepower” poles that provide for both power and telephone wiring. (They are costly to rearrange and can be unattractive)

·        Raised Floor—widely used in computer rooms where a great deal of cabling and rearrangement is needed. Very flexible, but also very expensive 

·        Under-Carpet Cabling—flat telecommunications and power cabling can be put under specially designed carpet. Layout must be carefully planned to avoid crossovers. Less flexibility, rearrangement costly

·        Terminating Jacks: Telephone wiring normally terminated in 8 conductor RJ-45 jacks. Where data and phone terminals are installed together, usually terminated in wall plates with multiple jacks. Labeling is important, as is jack quality. Must be as high as wiring, otherwise bandwidth will be compromised

Vendor Selection

·        Can issue RFP or invitation to bid

·        Relying on EIA/TIA standards you can set forth requirements and select vendor with lowest price, without compromising project

·        RFP should include: 1) floor plan showing location and type of jacks, location of Equipment room and Telecommunications closets, entrance cables, conduits, etc., 2) specifications on expectations of contractor, 3) furnishing of materials and acceptable manufacturers, 4) product requirements, 5) testing methods and testing results required

·        Should insist that contractor use compatible components

Manufacturer Support

·        Good idea to require manufacturer’s extended performance warranty, that states that product fails to meet specifications for category, that the manufacturer will correct problem

·        Find out from vendor what products they are certified to install, what products they prefer

·        Length of warranties and information on inspections

Installation Quality

·        Installation quality is as important as the product itself, if not more so!  Inquire about:

·        How many factory-certified installers are available, what kinds of duties do noncertified installers perform

·        Are there quality manuals, etc. available

·        What is their quality inspection process

Testing

·        As a purchaser, expect the contractor to test all of the wire runs and provide a copy of the test results

·        Find out how they will test the system and what product they will use to perform the testing

·        Ask questions regarding their process for clearing discrepancies

·        When can you expect the test results