Technical Information Glossary Sizing: Applying a material to a surface to fill pores. Skeleton Braid: Widely separated braid of fiber copper or steel, used to hold core together, for reinforcing jacket or for shielding. Standing Wave Ratio (SWR): In a transmission line, waveguide, or analogous system, a figure of merit used to express the efficiency of the system in transmitting power. Skew Rays: A ray that does not intersect the fiber axis. Generally, a light ray that enters the fiber core at a very high angle. Skim Tape: Filled tape coated on one or both sides with a thin film of uncured rubber or synthetic compound to produce a coating suitable for vulcanization. Skin Effect: The tendency of alternating current, as its frequency increases, to travel only on the surface of a conductor. Sleeve: A braided, knitted or woven tube used over wires or components as insulation tubing. Also called Sleeving. Solid Conductor: A conductor consisting of a single wire. Source Coupling Loss: (fiber optic) Loss of light intensity as light from source passes into fiber. Space, Telecommunications: An area used for housing the installation and termination of telecommunications equipment and cable, e.g. telecommunications closets, work areas and manhole/handholes. Span: (1.) In flat conductors, distance between the reference edge of the first and the last conductor. (2.) In round conductors, distance between centers of the first and last conductors. (3.) In aerial cable, the distance between poles or support clamps. Spark Test: A test designed to locate pin-holes in the insulation of a wire or cable by application of a voltage for a very short period of time while the wire is being drawn through the electrode field. Specific Gravity: The ratio of the density (mass per unit volume) of a material to that of water. Spectral Bandwidth: The difference between wavelengths at which the radiant intensity of illumination is half its peak intensity. Spectral Response: (fiber optic) The response of a detector (or a system) over different wavelengths. Spectrum: Frequencies that exist in a continuous range and have a common characteristic. Speed of Light (c): 2.998 x 108 meters per second. Spiral Shield: A metallic shield of fine-stranded wires applied spirally rather than braided. Spiral Stripe: A color-coding stripe applied helically to the surface of an insulated wire or cable. Spiral Wrap: The helical wrap of a tape or thread over a core. Splice: A joining of conductors, generally from separate sheaths. Splice Closure: A device used to protect a cable or wire splice. Spread Spectrum: A modulation technique for multiple access, or for increasing immunity to noise and interference. Standing Wave: The stationary pattern of waves produced by two waves of the same frequency traveling in opposite directions on the same transmission line. Stay Cord: A component of a cable used to anchor the cable ends at their points of termination and to keep any pull of the cable from being transferred to the electrical connections. Strand: One of the wires of any stranded conductor. Telecommunications: The communication of information over some distance, including interbuilding and intrabuilding distances. Star Topology: A topology in which each telecommunications outlet/connector is directly cabled to the distribution device. Telecommunications Closet: See Closet, Telecommunications. Step Index Fiber: (fiber optic) A multimode fiber consisting of a core of uniform refractive index surrounded by cladding of slightly lower refractive index. Strand Lay: The distance of advance of one strand of a spirally stranded conductor, in one turn, measured axially. Telecommunications Entrance Room or Space: See Entrance Room or Space, Telecommunications. Telecommunications Entrance Facility: See Entrance Facility, Telecommunications. Telecommunications Entrance Point: See Entrance Point, Telecommunications. Telecommunications Equipment Room: See Equipment Room, Telecommunications. Electronics Telecommunications Grounding Busbar: A common point of connection for telecommunications system and bonding to ground, which is located in the telecommunications closet or equipment room. Stranded Conductor: A conductor composed of groups of wires twisted together. Telecommunications Infrastructure: See Infrastructure, Telecommunications. Strap: Square- or rectangular-section bare conductor manufactured and used in coil form. Strip: To remove insulation from a cable. Structural Return Loss: Backward reflected energies from uneven parts of the cable structure causing impedance variations are termed structural return loss. Telecommunications Outlet/Connector: See Outlet/Connector, Telecommunications. Telemetry Cable: Cable used for transmission of information from instruments to the peripheral recording equipment. Surface Resistivity: The resistance of a material between two opposite sides of a unit square of its surface. It is usually expressed in Ω. Surge: A temporary and relatively large increase in the voltage or current in an electric circuit or cable. Also called Transient. Suspended Ceiling: See False Ceiling. Sweep-test: Pertaining to cable, the frequency response is verified by generating an rf voltage whose frequency is swept repeatedly through a given frequency range at a rapid constant rate while the cable response is observed. Take-Up: The process of accumulating wire or cable onto a reel, bobbin or some other type of pack. Also, the device for pulling wire or cable through a piece of equipment or machine. Tape: A relatively narrow woven or cut strip of fabric, paper or film material. Tape Wrap: A spirally applied tape over an insulated or uninsulated wire. Tank Test: A voltage dielectric test in which the test sample is submerged in water and voltage is applied between the conductor and water as ground. Tape Cable: A form of multiple conductor consisting of parallel metal strips imbedded in insulating material. Taped Insulation: Insulation of helically wound tapes applied over a conductor or over an assembled group of insulated conductors. TB: Terminal Block Tear Strength: The force required to initiate or continue a tear in a material under specified conditions. Teflon®: DuPont company trade name for fluorocarbon resins. FEP, PFA and TFE are typical materials. Tensile Strength: The pull stress required to break a given specimen. Temperature Rating: The maximum temperature at which an insulating material may be used in continuous operation without loss of its basic properties. Tension Member: A member included in a fiber cable to add tensile strength. Terminal: (1) A point at which information may enter or leave a communications network; (2) the input-output associated equipment; or (3) a device by means of which wires may be connected to each other. Termination Hardware: This term is outmoded. See Connecting Hardware. Test Lead: A flexible, insulated lead wire used for making tests, connecting instruments to a circuit temporarily or for making temporary electrical connections. Textile Braid: Any braid made from threads of cotton silk, or synthetic fibers. Thermal Aging: Exposure to a thermal condition or programmed series of conditions for predescribed periods of time. Thermocouple Lead Wire: An insulated pair of wires used from the couple to a junction box. Thermoplastic: A material which softens when heated and becomes firm on cooling. Thermoset: A material which hardens or sets when heat is applied, and which, once set, cannot be resoftened by heating. The application of heat is called “curing.” Taping: Process of insulating continuous length, large diameter wires with tape of non-extrudable materials. Three-Phase Current: Current delivered through three wires, with each wire serving as a return for the other two. Tefzel®: DuPont trade name for a fluorocarbon material typically used as a wire wrap insulation. Three-Wire System: A d-c or single-phase a-c system comprising three conductors, one of which is maintained at a potential midway between the potential of the other two. Tin Overcoat (TOC): Tinned copper wire, stranded, then coated with pure tin. Three-Phase Three-Wire System: An alternating current supply system comprising three conductors over which three-phase power is sent. 189