Accelerated Aging
A test in which voltage, temperature, etc., are increased above normal operation values to obtain observable deterioration in a relatively short period of time. The plotted results give expected service life under normal conditions.
The measure of the ease with which an alternating current flows in a circuit. The reciprocal of impedance.
Aerial Cable
A cable suspended in the air on poles or other overhead structure.
Air-Dielectric Coaxial Cable
One in which air is the essential dielectric material. A spirally wound synthetic filament or spacer may be used to center the conductor.
A metal formed by combining two or more different metals to obtain desirable properties.
Alternating Current
Electric current that continually reverses its direction. It is expressed in cycles per second (Hertz or Hz).
Ambient Temperature
The temperature of a medium (gas or liquid) surrounding an object.
American Wire Gauge (AWG)
A standard system for designation wire diameter. Also referred to as the Brown and Sharpe (B&S) wire gauge.
The unit of current. One ampere is the current flowing through one Ohm of resistance at on volt potential.
Relief of mechanical stress through heat and gradual cooling. Annealing copper renders it less brittle.
A braid or wrapping of metal, usually steel, used for mechanical protection. Generally placed over the outer sheath.
Abbreviation for the American Society for Testing and Materials, a nonprofit industry-wide organization which publishes standards, methods of test, recommended practices, definitions and other related material.
Power loss in an electrical system in cables, generally expressed in dB per unit length, usually 100 ft.
Audio Frequency
The range of frequencies audible to the human ear. Usually 20-20,000 HZ.
Abbreviation for American Wire Gauge.
Designation for Appliance Wiring Material.
A fibrous or metallic group of filaments interwoven in cylindrical form to form a covering over one or more wires. Braid Angle The smaller of the two angles formed by the shielding strand and the axis of the cable being shielded.
Braid Angle
The smaller of the two angles formed by the shielding strand and the axis of the cable being shielded.
Braid Carrier
A spool or bobbin on a braider which holds one group of strands or filaments consisting of a specific number of ends. The carrier revolves during braiding operations.
Braid Ends
The number of strands used to make up one carrier. The strands are wound side by side on the carrier bobbin and lie parallel in the finished braid.
Breakdown Voltage
The voltage at which the insulation between two conductors breaks down.
Bunch Stranding
A group of wires of the same diameter twisted together without a predetermined pattern.
Buried Cable
A cable installed directly in the earth without use of underground conduit. Also called "direct burial cable."
An insulated conductor, or group of individually insulated conductors in twisted or parallel configuration.
Cable Assembly
A completed cable and its associated hardware ready to install.
The twisting together of two or more insulated conductors to form a cable.
Cabling Factor
Used in the formula for calculation the diameter of an unshielded, unjacketed cable. D = Kd, where D is the cable diameter, K is the factor and d is the diameter of one insulated conductor.
The ratio of the electrostatic charge on a conductor to the potential difference between the conductors required to maintain that charge.
Characteristic Impedance
The impedance that, when connected to the output terminals of a transmission line of any length, makes the line appear infinitely long. The ratio of voltage to current at every point along a transmission line on which there are no standing waves.
Circular Mil
The area of a circle one mil (.001") in diameter; 7.854 x 10 - 7 sq. in. Used in expressing wire cross sectional area.
A method of applying a layer of metal over another metal whereby the junction of the two metals is continuously welded.
Coaxial Cable
A cable consisting of two cylindrical conductors with a common axis, separated by a dielectric.
Color Code
A system for circuit identification through use of solid colors and contrasting tracers.
Concentric Stranding
A central wire surrounded by one or more layers of helically wound strands in a fixed geometric arrangement.
In a wire or cable, the measurement of the location of the center of the conductor with respect to the geometric center of the surrounding insulation.
The capability of a material to carry electrical current-usually expressed as a percentage of copper conductivity (copper being 100%).
An uninsulated wire suitable for carrying electrical current.
A tube or trough in which insulated wires and cables are run.
A device used to physically and electrically connect two or more conductors.
Continuity Check
A test to determine whether electrical current flows continuously throughout the length of a single wire or individual wires in a cable.
A compound resulting from the polymerization of two different monomers.
In cables, a component or assembly of components over which additional components (shield, sheath, etc.) are applied.
The percent of completeness with which a metal braid covers the underlying surface.
The minute cracks on the surface of plastic materials.
Abbreviation for Canadian Standards Association, a non-profit, independent organization which operates a listing service for electrical and electronic materials and equipment. The Canadian counterpart of the Underwriters Laboratories.
Cut-Through Resistance
The ability of a material to withstand mechanical pressure, usually a sharp edge or small radius, without separation.
Decibel (dB)
A unit to express differences of power level. Used to express power gain in amplifiers or power loss in passive circuits or cables.
Any insulating material between two conductors which permits electrostatic attraction and repulsion to take place across it.
Dielectric Constant (K)
The ratio of the capacitance of a condenser with dielectric between the electrodes to the capacitance when air is between the electrodes. Also called Permitivity and Specific Inductive Capacity.
Dielectric Strength
The voltage which an insulation can withstand before breakdown occurs. Usually expressed as a voltage gradient (such as volts per mil).
Direct Current Resistance (DCR)
The resistance offered by any circuit to the flow of direct current.
Dissipation Factor
The tangent of the loss angle of the insulation material. (Also referred to as loss tangent, tan, and approximate power factor).
Drain Wire
In a cable, the uninsulated wire laid over the component or components and used as a ground connection.
Like concentricity, a measure of the center of a conductor's location with respect to the circular cross section of the insulation. Expressed as a percentage of displacement of one circle within the other.
The fractional increase in length of a material stressed in tension.
Abbreviation for electromagnetic interference.
In braiding, the number of essentially parallel wires or threads on a carrier.
Figure 8 Cable
An aerial cable configuration in which the conductors and the steel strand which supports the cable are integrally jacketed. A cross section of the finished cable approximates the figure "eight."
Flame Resistance
The ability of a material not to propagate flame once the heat source is removed.
Flex Life
The measurement of the ability of a conductor or cable to withstand repeated bending.
A flammability rating established by Underwriters Laboratories for wires and cables that pass a specially designed vertical flame test. This designation has been replaced by VW-1.
Gauge (AWG)
A term used to denote the physical size of a wire.
A numerical prefix denoting one billion (109).
A conduction connection between an electrical circuit and the earth or other large conduction body to serve as an earth thus making a complete electrical circuit.
Hard Drawn Copper Wire
Copper wire that has not been annealed after drawing. Sometimes called HD wire.
Hertz (Hz)
A term replacing cycles-per-second as an indication of frequency.
A test designed to determine the highest voltage that can be applied to a conductor without breaking through the insulation.
Dupont???s trade name for their chlorosulfinated polyethylene, and ozone resistant synthetic rubber.
The total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency. It is a combination of resistance R and reactance X, measured in Ohms.
The property of a circuit or circuit element that opposes a change in current flow, thus causing current changes to lag behind voltage changes. It is measured in henrys.
A material having high resistance to the flow of electric current. Often called a dielectric in radio frequency cable.
Insulation Resistance
The ratio of the applied voltage to the total current between two electrodes in contact with a specific insulation, usually expressed in megaOhms-M feet.
An outer non-metallic protective covering applied over an insulated wire or cable.
A numerical prefix denoting 1000 (103).
The length measured along the axis of a wire or cable required for a single strand (in stranded wire) or conductor (in cable) to make one complete turn about the axis of the conductor or cable.
Longitudinal Shield
A tape shield, flat or corrugated, applied longitudinally with the axis of the core being shielded.
Loop Resistance
Sum of conductor resistance and shield resistance (DCR).
Energy dissipated without accomplishing useful work.
Low Loss Dielectric
An insulating material that has a relatively low dielectric loss, such as polyethylene or Teflon.
MegaHertz (one million cycles per second).

Meg or Mega
Formerly mc

A numerical prefix denoting 1,000,000 (106).
A numerical prefix denoting one-millionth (10-6).
A unit used in measuring diameter of a wire or thickness of insulation over a conductor. One one-thousandth of an inch (.001").
Modulus of Elasticity
The ratio of stress to strain in an elastic material.
The basic chemical unit used in building a polymer.
Mutual Capacitance
Capacitance between two conductors when all other conductors including ground are connected together and then regarded as an ignored ground.
A numerical prefix denoting one-billionth (10-9).
National Electrical Code (NEC)
A consensus standard published by the National Fire Protection Association (NFPA) and incorporated in OSHA regulations.
Abbreviation for Oxygen-Free, High Conductivity copper. It has no residual deoxidant, 99.95% minimum copper content and an average annealed conductivity of 101%.
A unit of electrical resistance.
Oxygen Index
Percentage of oxygen necessary to support combustion in a gas mixture.
Percent Conductivity
Conductivity of a material expressed as a percentage of that of copper.
The uniformly spaced variations in the insulation diameter of a transmission cable that result in reflections of a signal, when its wavelength or a multiple thereof is equal to the distance between two diameter variations.
Distance between two adjacent crossover points of braid filaments. The measurement in picks per inch indicates the degree of coverage.
A numerical prefix denoting one-trillionth.
In flat cable, the nominal distance between the index edges of two adjacent conductors.
A chemical agent added to plastics to make them softer and more pliable.
A material of high molecular weight formed by the chemical union of monomers.
Any of the polymers and copolymers of the ethylene family of hydrocarbons.
Four layers of shielding.
RG is the military designation for Radio Guide coaxial cable, and U stands for ???general Utility.???

Rated Temperature
The maximum temperature at which an electric component can operate for extended periods without loss of its basic properties.
Rated Voltage
The maximum voltage at which an electric component can operate for extended periods without undue degradation or safety hazard.
Reflection Loss
The part of a signal which is lost due to reflection of power at a line discontinuity.
Rope Lay Conductor
A conductor composed of a central core surrounded by one or more layers of helically laid groups of wires.
The outer covering or jacket of a multiconductor cable.
In cables, a metallic layer placed around a conductor or group of conductors to prevent electrostatic or electromagnetic interference between the enclosed wires and external fields.
Shield Effectiveness
The relative ability of a shield to screen out undesirable radiation. Frequently confused with the term shield percentage, which it is not.
Skin Effect
The phenomenon in which the depth of penetration of electric currents into a conductor decreases as the frequency increases.
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.
Spiral Wrap
The helical wrap of a tape or thread over a core.
A single uninsulated wire.
Stranded Conductor
A conductor composed of groups of wires twisted together.
Strip Force
The force required to remove a small section of insulation material from the conductor it covers. Usually measured in pounds.
Surface Resistivity
The resistance of a material between two opposite sides of a unit square of its surface. It is usually expressed on Ohms.
Sweep Test
Pertaining to cable, checking frequency response by generation an rf voltage whose frequency is varied back and forth through a given frequency range at a rapid constant rate and observing the results of an oscilloscope.
Tape Wrap
A spirally applied tape over an insulated or uninsulated wire.
Tear Strength
The force required to initiate or continue a tear in a material under specified conditions.
A numerical prefix denoting one quadrillionth (10-15).
Tensile Strength
The pull stress required to break a wire/cable.
Transmission Cable
Two or more transmission lines. If the structure is flat, it is sometimes called Flat Transmission Cable to differentiate it from a round structure such as a jacketed group of coaxial cables.
A cable tray system is a unit or assembly of units or sections, and associated fittings, made or metal or other noncombustible materials forming a rigid structural system used to support cables. Cable tray systems (previously termed continuous rigid cable supports) including ladders, troughs, channels, solid bottom trays, and similar structures.
Triaxial Cable
A cable construction having three coincident axes, such as conductor, first shield and second shield all insulated from one another.
Abbreviation for Ultra High Frequency, 300 to 3,000 MHz.
Abbreviation for Underwriters Laboratories, a nonprofit independent organization, which operates a listing service for electrical and electronic materials and equipment.
Velocity of Propagation
The speed of an electrical signal down a length of cable compared to speed in free space expressed as a percent. It is the reciprocal of the square root of the dielectric constant of the cable insulation.
Abbreviation for Very High Frequency, 30 to 300 MHz.
Abbreviation for Very Small Aperture Terminal, a small data satellite dish.
Video Pair Cable
A transmission cable containing low-loss pairs with an impedance of 125 Ohms. Used for TV pick ups, closed circuit TV, telephone carrier circuits, etc.
A unit of electromotive force.
Voltage Rating
The highest voltage that may be continuously applied to a wire in conformance with standards or specifications.
Voltage Standing Wave Ratio (VSWR)
The ratio of the maximum effective voltage to the minimum effective voltage measured along the length of a mis-matched radio frequency transmission line.
Abbreviation for voltage standing wave ratio.
A flammability rating established by Underwriters Laboratories for wires and cables that pass a specially designed vertical flame test, formerly designed FR-1.
Wall Thickness
The thickness of the insulation or jacket.
A unit of electric power.
Wave Length
The distance, measured in the direction of propagation, of a repetitive electrical pulse or waveform between two successive points that are characterized by the same phase of vibration.
A conductor, either bare or insulated.
Capacitance is the measurement of energy absorbed by the cable. It is caused by the difference in electrical potential of the conductors and is measured in picofarads per foot (pF/ft). Like impedance, it is related to the inner and outer conductor sizes and the core dielectric constant. In a given cable design, capacitance and impedance are inversely proportional. The fewer the picofarad per foot, the better the cable performance.

Capacitance is determined by the formula:

Where Er is the dielectric constant of the cable core, D is the dielectric diameter, d is the conductor diameter and a is the conductor stranding factor.


Characteristic impedance is a measurement of resistance to the electrical current being carried in a cable. It is measured in units called Ohms (ZO) and is directly related to the ratio between inner conductor dimension and the outer conductor dimension, and inversely related to the dielectric constant of the cable core. Unlike conductor resistance, impedance does not vary with cable length.

For a system to work at maximum efficiency, the nominal impedance of the transmitter, receiver and cable must precisely match. An incorrect match will produce reflection loss. Nominal impedance is determined by the formula:

The factors are the same as they are for capacitance above.

Structural Return Loss
Structural return loss is the measure of power loss on a cable or system and is caused by discontinuities in the cable conductor or dielectric. If these discontinuities are regularly spaced along a cable, they can cause severe transmission losses for frequencies whose wavelengths are twice that of the distance between these discontinuities.

Structural return loss is an unfavorable characteristic of poorly made cable, although careless installation can cause it as well. Liberty offers cable from manufacturing lines that are constantly computer monitored to avoid irregularities in the manufacturing process that could cause these flaws.

Velocity of Propagation

Nominal velocity of propagation is the speed of the signal in a given cable. In a vacuum, electromagnetic radiation (light, radio waves, etc.) travels at the speed of light. In a cable, it travels somewhat slower and in direct inverse proportion to the dielectric constant; the lower the dielectric constant, the closer to the speed of light the signal travels.

Velocity of propagation is given as a percent figure of the speed of light and is calculated by:

Where Er is the dielectric constant of the cable core.

NEC Cable Substitution and Hierarchy Chart

Type CM
Communication Wire and Cables
Type CL2 and CL3
Class 2 and Class 3 Remote-Control Signaling, and Power-Limited Cables
Type FPL
Power-Limited Fire Alarm Cable
Type MP
Multipurpose Cables
Power-Limited Tray Cables
Community, Antenna Television Systems
Cable A shall be permitted to be used in place of Cable B.

BC Bare Copper P Plenum
C Conductors PLN Plenum
CCS Copper Clad Steel Q Quad
DB Direct Burial SH Shielded or Shield
CMP Communications Plenum STR Stranded
CMR Communications Riser TC Tinned Copper
EX ExtraFlex TTP Tight Tube Plenum
INDSH Individual Shield UN Unshielded
(#) P Pair VID Video