The industry, however, is moving toward eight-position modular jacks. If you are renovating an office, again, you should look out for re-termination costs.
The best and most complete place the author has found to identify jacks for building construction is the chapter in BICSIs Telecommunications Distribution Methods Manual, titled Telecommunications Service Entrance and Termination.
J-hooks. Named because they resemble the letter J, these hooks are fastened to building steel and sometimes extended with a threaded rod, or anchored to the deck above and extended. J-hooks are available in a CAT 5 version where the bottom is flat and smooth so that the cable minimum-bending radius is not exceeded. They are also available in various sizes and are rated for a maximum number of wires and spacing. Look out for installations where the contractor straps the cable to the steel and then installs the J-hooks, the cable may be damaged. Look out for over-filling of the J-hook and also for exceeding the spacing requirements. Testing does not identify all cable damage.
Juke Box. An electronic box with multiple compact disks (CDs). The application is similar to a file server. A juke box serving a LAN will provide the users access to the multiple CDs.
Local Exchange. A system of one or more central offices and associated equipment that operates under one administration. A geographical area of a local exchange usually follows the layout of a town or city.
Laser Printer. A type of printer that uses a laser for printing. Laser printers are more expensive, faster, and of a higher-duty cycle than ink-jet printers and are more often found connected to a network, so that several people may share one printer.
Link. A link, with reference to horizontal wiring, includes the workstation outlet, the horizontal cabling, and the communications-closet patch panel. (Compare to definition of channel.)
NFPA. National Fire Protection Administration, a code-making body.
NEC. National Electrical code, NFPA 70 (often referred to as The Code), that most jurisdictions follow for electrical and communications work. NIC. Network interface cards are installed in PCs so that the PC may be connected to the LAN by patch cable.
OTDR. Optical time domain reflectometer, a fiberoptic cable test tool that locates fiber breaks and can determine loss per connection, splice, or segment.
OC. Optical carrier, a definition of optical transmission rate for SONET. The OC-1 transmission rate is 52 Mbps. The OC-3 transmission rate is 156 Mbps.
Patch Cable. The cable used to connect PCs to wall jack or system furniture jack. They are also used to connect network gear to patch panels in the communications closets.
Patch Panel. A rack-mounted panel of 12, 24, or 48 jacks. Cables from wall or system furniture outlets are terminated on the back. Patch cables are used to connect the patch panel directly to network gear or to the network gear patch panel.
Pathway. The path devised to take a cable or group of cables to a destination, including the support method, such as conduit, cable tray, wall sleeve, J-hooks, poke-through device, system furniture wireway, communications pole, surface raceway, or cable tied to steel. Cable tied to steel is mentioned because it is quite common, even though it is not a good practice. The cable tied to steel is strained, and the minimum-bending radius of the cable is easily exceeded.
PBX. Private branch exchange, other names which are, for all practical purposes, synonymous include: PABX, private automatic branch exchange; CBX, computerized branch exchange; telephone switch; or switch. A PBX is electronic gear that provides voice switching, processing, and other services, on the private voice network.
PETs. Protected-entrance terminals are lightning or surge protectors. They are provided by the LEC, or they are provided by the building owner, in accordance with the minimum requirements of the LEC. The protectors themselves are either carbon blocks, gas tubes, or solid-state devices. An individual protector is provided on each line. PETs are a combination of protectors and terminal. The terminals may be 66 type or 110 type for individual line connection or a highdensity type connector for connection to a PBX. A ground cable is connected to the PET to take the surge to ground.
Plenum Cable. Cable certified to be fire resistant and low-smoke producing. It can be installed in the ceiling cavity, between the false ceiling and the floor or ceiling above. The ceiling cavity is called a plenum. The plenum is often used for conveying air for heating and air conditioning. NEC requires plenum cable for cables passing through air plenums.
POTS. Plain old telephone service; the cable is referred to as a POTS line.
Protectors. They are either carbon blocks, gas tubes, or solid-state devices used to protect against lightning or electrical surges (see PETs). Any communication line which goes outside should be protected so that if a surge is induced in the line by a nearby lightning strike or a short circuit, the surge will not damage expensive electronic equipment. Protectors for data lines should be rated for the speed and type of line.
Protocol. A formal set of rules that allow data transmission. Format, timing, signal initialization, verification, addressing, poling, and error correction are included.
Punch-down Block. A device located in communications closets to terminate voice cable. A punch-down tool is used to make the termination. The action of the tool is similar to a punch, thus the name. The most common styles of punchdown blocks are the 66 type which are older and the 110 type which are newer and of higher density. The blocks are rated by category. Category 5 blocks are most commonly used in new construction.
Rack. An open frame to mount equipment or to mount patch panels and manage cables. The frames are usually an EIA/TIA 19-in wide standard, measured from center to center of the equipment mounting holes. Racks are found in the communications closets and the main communications room. EIA/TIA 23-in standard racks are sometimes found in the main communications room for PBX, voice communications gear, or other LEC gear. Enclosed racks are sometimes provided, typically by the CLEC or LEC to protect the equipment. Rackmounted backup power supplies are common (see UPS system).
Rectifier. A rectifier is a piece of electrical power equipment that turns 120 V, or higher ac current, to dc current. Old PBXs, and some new ones, require 48 to 52 V dc. The rectifier charges the batteries, the batteries feed a regulated power supply, and the power supply feeds the PBX. If the ac power fails, the batteries continue to power the system. It is like the battery charging system in a car.
Rectifier systems are usually found in the main communications room. The batteries may be quite large and heavy. Some buildings built prior to knowing the tenants requirements may not have the floor rating to support large battery racks without damage. Rectifier systems are being replaced by UPSs.
SBCCI. Southern Building Code Congress International provides technical, educational, and administrative support to governmental departments and agencies engaged in building codes administration and enforcement. SBCCI also provides similar support to others in the building design and construction industry.
SONET. Synchronous optical network is a high-speed, high-survivability network.
The topology is a ring where if one fiber fails, the other will continue to provide service. The equipment would appear as a minimum 23-in wide, 30-in deep, 72-in high enclosed rack or cabinet in the main communications room.
Two distinct and separate pathways are needed for the fiber. Two separate sets of manholes and ducts are required. SONET speeds may be OC-3 (156 Mbps), OC-12 (624 Mbps), and OC-48 (2.496 Gbps). Almost all types of services are available from a SONET cabinet because they are built to order.
STP. Shielded twisted-pair cable.
T1. A digital carrier formatted to transmit 1.544 Mbps divided into 24 channels.
A fractional T1 carries two to 23 channels. Cables used to transmit T1 service are two twisted pair which are separated or screened. A T1C transmits 3.152 Mbps divided into 48 channels. T1 on fiber is also used. (See DSU for interfacing copper T1s.)
TIA. Telecommunications Industry Association a trade organization representing the companies that provide communications and information technology products and services.
UL. Underwriters Laboratories Inc.
UPS. Uninterruptible power supplies, often provided to maintain the power supply to critical equipment. UPSs usually provide 120 V ac and derive their power from integral sealed batteries. They are rated for the amount of power and the duration in minutes at which rated power is sustained during an outage. UPSs may be floor mounted or rack mounted, or small units may be located at the PC. Some UPSs have network connections so they may communicate to the outside world when there is a power problem. (See Rectifier.)
USOC. Universal Service Order Code.
UTP. Unshielded twisted-pair cable.
WAN. Wide-area network, a network covering a wide geographical area using LEC or CLEC facilities.
