Tester Equipment Glossary



Alternating Current (AC):
This type of current is the most commonly used form of electricity, and is called alternating current because it frequently reverses direction when traveling through a circuit.


ABS (Acrylonitrile-butadiene-styrene):
A rigid thermoplastic terpolymer formed through injection, molding that is known for its high impact strength.


ABS Fire Retardant:
Flame retardant acrylonitrile-butadiene-styrene, a rigid, high impact thermoplastic combined with chemicals to reduce or retard the spread of fire over a surface.


A device that enables any or all of the following 1) different sizes or types of plugs to mate with one another or to fit into a telecommunications outlet/connector; 2) the rearrangement of leads; 3) large cables with numerous wires to fan out into smaller groups of wires; 4) interconnection between cables.


AFCI (Arc Fault Circuit Interrupter):
Circuit breaker designed to prevent fires by detecting non-working electrical arcs and disconnect power before the arc starts a fire.


Alligator Clip:
A mechanical device shaped like alligator jaws, used as a temporary connection on the end of interconnections wire.


See Current Carrying Capacity.

Breath or extent of a carrier wave in accordance to the strenght of the audio signal


Ampere (Amp):
The ampere, or amp, is the measure of an electrical current in a given circuit. A single amp is equal to 6,280,000,000,000,000,000 electrons passing a specific point in one second.


A signaling format that uses continuous physical variables such as voltage, amplitude, or frequency variations to transmit information.


A signaling device, usually electrically operated, that gives an audible or visual signal (or both) when energized.


abbreviation for the American National Standards Institute.


Arc Resistance:
The time required for an arc to establish a conductive path in a material.


Attenuation: A decrease in the magnitude of a signal’s power during transmission between points. Attenuation is usually measured in decibels per unit length, at a specific frequency.


Attenuation to Crosstalk Ratio (ACR):
A ratio that compares attenuated signal to the amount of near end crosstalk. This measurement is used to calculate how far signals can be sent through different types of wire.


Audio Frequency:
The range of frequencies audible to the human ear, which is usually the range of 20-20,000 Hz.


A method for testing signal loss in fiber optic cables.


A device for matching an unbalanced coaxial transmission line to a balanced two-wire system.


Or Bit Error Rate Test is a testing method for digital communication circuits that uses predetermined stress patterns comprising of a sequence of logical ones and zeros generated by a pseudorandom binary sequence.
A BERT Tester typically consists of a test pattern generator and a receiver that can be set to the same pattern. They can be used in pairs, with one at either end of a transmission link, or singularly at one end with a loopback at the remote end. BERT Testers are typically stand-alone specialised instruments, but can be Personal Computer based. In use, the number of errors if any are counted and presented as a ratio such as 1 in 1,000,000, or 1 in 10e06.


One binary (0 or 1) digit.


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Bond Strength:
Amount of adhesion between bonded surfaces, e.g. in cemented ribbon cable.


Bondable Wire:
These can include the insulated wires that are treated to facilitate adherence to materials such as potting compounds, as well as magnetic wires used to make coils when the bonding together of turns is desired.


Bonded Cable:
Cable consisting of pre-insulated conductors or multiconductor components, which are laid- in parallel and bonded into a flat cable. See Solvent-Bonded; Adhesive-Bonded; Film-Bonded .


Bonded Construction:
An insulation construction in which the glass braid and nylon jacket are bonded together.


The permanent joining of metallic parts to form an electrically conductive path that will assure electrical continuity and the capacity to safely conduct any current that is likely to be imposed on it.


A device inserted into a line (or cable) to increase the voltage.


Breakdown Voltage:
The voltage level at which the insulation between two conductors breaks down.


The Celsius temperature scale (previously known as the centigrade scale). The degree Celsius (symbol: °C) can refer to a specific temperature on the Celsius scale as well as serve as unit increment to indicate a temperature interval (a difference between two temperatures or an uncertainty). "Celsius" is named after the Swedish astronomer Anders Celsius (1701 - 1744), who developed a similar temperature scale two years before his death.

Chlorofluorocarbon, a chemical compound found in many aerosol products or manufacturing processes and believed to be responsible for depleting the Earth’s diminishing ozone layer.


Calibration :
Zeroing of an instrument to a known standard


Canadian Standards Association (CSA):
An independent, not-for-profit organization, which operates a listing service for electrical equipment and electronic materials , and is recognized as the Canadian counterpart of Underwriters Laboratories (UL).


The ratio of an electrostatic charge on a given conductor, to the potential difference between the conductors required for that charge to be maintained.


Capacitance, Direct:
The capacitance measured from one conductor to another conductor through a single insulating layer.


Capacitance, Mutual:
The capacitance between two conductors (typically of a pair), with all other conductors, including shield, short-circuited to ground.


A complete path, over which electrons can flow – through parts and wires – from the negative terminals of a voltage source to the positive terminals of the same voltage source.


Circuit Breaker:
An automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit.


Circuit Sizes:
A popular term for building wire sizes 14 through 10 AWG.


Closed Circuit Television (CCTV):
Is the use of video cameras to transmit signal to a specific, limited set of monitors.

The capacity of a material to carry electrical current—usually expressed as a percentage of copper conductivity (copper being 100%).


A wire, or combination of wires that are not insulated from one another, which are suitable for carrying electrical current.


Conductor Impedances:
Electrical impedance or simply impedance is a measure of opposition to a sinusoidal electric current. The concept of electrical impedance generalizes Ohm's law to AC circuit analysis.


A device used to provide rapid connect/disconnect service for electrical cable and wire terminations.

Continuity Check:
A test to determine whether or not an electrical current flows continuously throughout the length of a single wire, or individual wires in a cable.


Controlled Impedance Cable:
Package of two or more insulated conductors, in which impedance measurements between the respective conductors are kept essentially constant throughout the entire length.


The conduction of electricity across the surface of a dielectric.


Undesired electrical currents in conductors, which are caused by electromagnetic or electrostatic coupling from other conductors or from external sources. The term “crosstalk” can also describe the leakage of optical power from one optical conductor to another.


The rate of transfer of electricity. The practical unit used in the measurement of current is the ampere, which represents the transfer of one coulomb per second. In a simple circuit, current (I) is produced by a cell or electromotive force (E) when there is an external resistance (R) and internal resistance (r) is: l = E R+r


Current Carrying Capacity:
The maximum current an insulated conductor can safely carry without exceeding its insulation and jacket temperature limitations.


Customer Premises:
Building(s) with grounds and appurtenances (belongings) under the control of the customer.


Cut-Through Resistance:
The ability of a material to withstand mechanical pressure, usually a sharp edge or small radius, without separation.


The complete sequence, including flow reversal , of an alternating electric current.


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.


Delay Line:
A cable made to provide a very low propagation velocity with long electrical delay for transmitted signals.


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Derating Factor:
A factor used to reduce the current-carrying capacity of a wire, when the wire is used in environments other than those for which the current value was established.


An insulating medium, which intervenes between two conductors and permits electrostatic attraction and repulsion to take place across it.


Dielectric Breakdown:
The amount of voltage required to cause an electrical failure or break through the insulation.


Dielectric Constant (K):
The ratio of a condenser’s capacitance with a dielectric between the electrodes, to its capacitance when air is between the electrodes. Also called Permittivity and Specific Inductive Capacity.


Dielectric Loss:
Power dissipated in an insulating medium, as the result of the friction caused by molecular motion when an AC electric field is applied.


Dielectric Strength:
The level of voltage that insulation can withstand before breakdown occurs. Usually expressed as a voltage gradient (such as volts per mil).


Dielectric Test:
A test, in which a current that exceeds a dielectric’s voltage rating is applied to that dielectric for a specified time, to determine the adequacy of the insulation under normal conditions.


Computer data that is expressed in numerical form.


Dynamic Host Configuration Protocol (DHCP):
Is a protocol used by networked devices (clients) to obtain various parameters necessary for the clients to operate in an Internet Protocol (IP) network. By using this protocol, system administration workload greatly decreases, and devices can be added to the network with minimal or no manual configurations.


Dip Coating:
An insulating coating, which is applied to a conductor by passing the conductor through an applicator containing the liquid insulating medium.


Direct Burial Cable:
A cable installed directly in the earth.


Direct Capacitance:
The capacitance measured directly from conductor to conductor, through a single insulating layer.


Direct Current (DC):
An electric current that flows in only one direction.


Direct Current Resistance (DCR):
Any circuit’s resistance to the flow of direct current.


Disruptive Discharge:
A sudden, large increase in current through an insulation medium, due to the complete failure of that medium under electrostatic stress.


Disturbed Conductor:
A conductor that receives energy generated by the field of another conductor, or by an external source such as a transformer.


Two-way data transmission over a four-wire transmission line or two fibers.


Duplex Cable:
(1) A cable composed of two insulated single-conductor cables twisted together. (2) A cable composed of two fibers, typically 62.5/125 pm Multi-Mode, placed parallel under a thermoplastic sheath.


Duplex Parallel:
A termtypically used in the thermocouple industry to denote two parallel conductors of dissimilar metals, insulated in parallel without twist and jacketed. Commonly applied to thermocouple grades and extension wires.


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 one circle’s displacement within the other.


Eddy Current:
Circulating currents induced in conducting materials by varying magnetic fields.


Equipment Protective Device.


A rubber or rubber-like material, which will repeatedly stretch 200 percent or more, then return forcefully and rapidly to its approximate original shape.


Theelectrolytic process of tinning wire, using pure tin.


A medium through which a current enters or leaves a nonmetallic conductor.


Electromagnetic Coupling:
Energy transfer by means of a varying magnetic field.


Electromagnetic Field:
A rapidly moving electrical field and its associated moving magnetic field.


Electromagnetic Induction:
The production of voltage in a coil, due to a change in the number of magnetic lines of the forces (flux linkages) passing through that coil.


Electromagnetic Interference (EMI):
The interference in signal transmission or reception resulting from the radiation of electrical and magnetic fields. Synonym: Radio Frequency Interference.


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Electromotive Force (EMF):
Pressure or voltage, the forces that cause current to flow in a circuit.


Electronic Wire and Cable:
A length of conductive or semi-conductive material used in an electronic application.


Pertaining to static electricity, or electricity at rest; for example, an electric charge.

EMI / RFI - Shielding:
Electromagnetic interference (EMI) is electrical noise which creates a disturbance or undesired response in circuits, equipment, or systems. EMI is a generalization of an older term, radio-frequency interference (RFI). Many types of electrical circuits are susceptible to EMI/RFI and must be shielded to ensure proper performance.
Shielding is the use of materials to reduce radiated EMI/RFI by reflection and/or absorption. Shielding should be placed where it best causes an abrupt discontinuity in the path of electromagnetic waves. Shielding effectiveness and performance is a function of the properties and configuration of the shielding materials, the frequency and the distance from the source to the shield.


Emergency Overload:
Overload that occurs when larger-than-normal currents are carried through a cable or wire over a certain period of time.


Is the ratio of the radiation emitted by a surface to the radiation emitted by a blackbody at the same temperature. It is therefore a measure of a material's ability to emit infrared energy. Materials are assigned an emissivity value between 0 and 1.0. Most organic materials such as paints, plastics, fabrics and food have an emissivity value near 0.95. Low cost IR (Infrared) meters typically have a factory fixed emissivity setting of 0.95.


Is a family of frame-based computer networking technologies for local area networks (LANs). The name comes from the physical concept of the ether. It defines a number of wiring and signaling standards for the physical layer, through means of network access at the Media Access Control (MAC)/Data Link Layer, and a common addressing format.
Ethernet is standardized as IEEE 802.3. The combination of the twisted pair versions of Ethernet for connecting end systems to the network, along with the fiber optic versions for site backbones, is the most widespread wired LAN technology. It has been in use from around 1980[1] to the present, largely replacing competing LAN standards such as token ring, FDDI, and ARCNET. In recent years, Wi-Fi, the wireless LAN standardized by IEEE 802.11, is prevalent in home and small office networks and augmenting Ethernet in larger installations.


External Interference:
The effects of electrical waves or fields, which cause “noise” that is not related to the desired signal. Static.


Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686-1736), the German physicist who proposed it in 1724.


A unit of electrical capacity.


Fatigue Resistance:
Resistance to metallic crystallization, a condition that causes conductors and wires to break when flexed.


Feed-Through Insulators:
Insulators that carry a metal conductor through a chassis, while preventing the "hot" lead from shorting to the ground chassis.


Energy that is extracted from a high- level point in a circuit and applied to a lower level. Positive feedback reduces the stability of a device and is used to increase the sensitivity or produce oscillation in a system. Negative feedback, also called inverse feedback, increases the stability and fidelity of a system.


A short tube used to make solder-less connections to coaxial or shielded cable.


The area of influence around a magnet or electric charge.


Field Coil:
A type of winding insulation that is suitable to be mounted on a field pole in order to magnetize it.


Fiber characterized by extreme length.


Fire Retardant:
A substance or chemical used to reduce flammability or to retard spread of a fire over a surface.


A disruptive discharge around or over the surface of a solid or liquid insulator.


Referring to a circuit, which has no connection to ground.

(1) The lines of force, which make up an electrostatic field. (2) The rate of energy flow across or through a surface. (3) A substance used to promote or facilitate fusion.


The number of times a periodic action occurs within a unit of time; the number of cycles that an electric current completes in one second.


Frequency Response:
The range of frequencies over which a given device may be effectively used.


Funnel Entry:
Flared or widened entrance to a terminal or connector wire barrel.


Fuse Wire:
Wire made from an alloy that melts at a relatively low temperature.


The increase of voltage, current or power over a standard or previous reading. Usually expressed in decibels.


An instrument used for detecting or measuring small electrical currents.

GFCI (Ground Fault Circuit Interrupter):
Inexpensive electrical device that helps to prevent electrical shock and burns.


Gigahertz (GHz):
A unit of frequency equal to one billion hertz.


A short length of wire soldered onto a circuit component and used as a small adjustable capacitor.

Global Warming:
The increase in the average temperature of the Earth's near-surface air and oceans since the mid-twentieth century and its projected continuation.

A conducting connection, whether intentional or accidental, that occurs between an electrical circuit (e.g. telecommunications) or equipment and the earth or another conducting body.


Ground Conductor:
A conductor found in a transmission cable or line that is grounded.


Ground Impendance:
The ground resistance and the inductance/capacitance value of the grounding system. Also called dynamic surge ground impedance.


Ground Insulation:
The insulation used between a winding and the magnetic core or other structural parts, usually at ground potential.


Ground Loop:
The generation of undesirable current flow within a ground conductor, owing to the circulation currents that originate from a second source of voltage.


Ground Potential:
Zero potential, with respect to the ground or earth.


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The unit of inductance.

Hydrochlorofluorocarbon, a chemical compound used in aerosol cans.

Hertz (Hz):
A term replacing cycles-per-second as an indication of frequency.


High Voltage:
Generally, a wire or cable with an operating voltage of over 600 volts.


Holding Strength:
Theability of a connector to remain assembled to a cable while under tension.


IEEE 802.3 Specifications:
Information technology - Telecomunications and information exchange between systems - Local and Metropolitan area networks - Specific requirements part 3: Carrier Sense Multiple Access with Collicion Detection (CSMA/CD) Access method and physical layer.

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 ~.


Impedance Matching Transformer:
A transformer designed to match the impedance of one circuit to that of another; see Balun.


A surge of unidirectional polarity.


Impulse Strength:
The breakdown of insulation under voltage surges, on the order of microseconds in duration.


Impulse Test:
A test in which impulse-voltage of a specified wave shape is applied to insulation.


Index of Refraction:
The ratio of light’s velocity in a vacuum to its velocity in a given transmitting medium.


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.


Inductive Coupling:
A type of crosstalk, resulting from the action of one conductor’s electromagnetic field on another conductor.


Insertion Loss:
The measure of a device’s attenuation, determined by a system’s output before and after that device is inserted into it.

A chemical link between two atoms caused by the electrostatic force between oppositely-charged ions in an ionic compound.

Chemical compound made up of six carbons connected by single bonds. These are frequently used as an inert solvent in organic reactions because they are non-polar. Often used as a cleansing agent for textile manufacturing.


Insertion Tool:
A small, hand-held tool used to insert contacts into a connector.


Insulating Joint:
A device, which mechanically couples and electrically insulates the sheath and armor of contiguous lengths of cable.


Insulation Crimp:
The area of a terminal, splice or contact that has been formed around a wire’s insulation .


Insulation Grip:
Extended cylinders at the rear of crimp-type contacts, designed to accept bared wire and a small length of its insulation.


Insulation Piercing:
A method of crimping, in which lances cut a wire’s insulation and enter into its strands to make electrical contact.


Insulation Resistance:
The ratio of applied voltage to the total current traveling between two electrodes in contact with a specific insulation, usually expressed in meg~-M feet.


Insulation System:
All of the insulation materials used to insulate a particular electrical or electronic product.


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The mechanical joining-together of devices to complete an electrical circuit.


Alternately functioning and not functioning or alternately functioning properly and improperly.


Ionization Voltage (Corona Level):
The minimum value of falling root mean square (RMS) voltage, which sustains electrical discharge within the vacuous or gas- filled spaces in a cable’s construction or insulation.


The mechanical feature of a connector system that either guarantees correct orientation of a connection, or prevents connection to a jack or optical fiber adapter which is of the same type but intended for another purpose.


A wire, with or without terminals, that connects two points in a circuit.


A cable that is cured or vulcanized in a metallic lead mold.


Lead Dress:
The placement or routing of wire and component leads in an electrical circuit.


Leakage Current:
The undesirable flow of current, either over or through the surface of insulation.


Local Light Injection and Detection System, an alignment method used on fibers being spliced or connected, in which optical power transmitters and detectors are used to ensure that light is being effectively transmitted from one fiber to the next.


Line Balance:
The degree to which the electrical characteristics of a cable’s conductors are alike, in relationship to each other, to other conductors and to the ground.


Line Drop:
A voltage loss occurring between any two points in a transmission line, due to the resonance, reactance or leakage of that line.


Line Loss:
The total of the various energy losses occurring in a transmission line.


Line Voltage:
Voltage existing in a cable or circuit.


Link: An assembly of telecommunications facilities between two points, not including terminal equipment.


Equipment included in a list published by an organization or authority which maintains periodic inspection of the production of listed equipment, and whose listing states either that the equipment or material meets appropriate standards or has been tested and found suitable for use in a specified manner.


Local Area Network (LAN):
A geographically limited communications network intended for the local transport of data, video and voice.


Loop Resistance:
A commonly used term in the thermo-coupling industry, which describes the total resistance of two conductors, measured round-trip from one end.


A wiring method that avoids tee joints by carrying a conductor or cable to and from the point to be supplied.


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Energy dissipated without accomplishing useful work.


Loss Factor:
The product of the dissipation and dielectric constant of an insulating material.


Lossy Line:
A cable having a large rate of attenuation per unit of length.


Low-Noise Cable:
Cable configuration specially constructed to eliminate spurious electrical disturbances caused by capacitance changes or the self-generated noise induced by either physical abuse or adjacent circuitry.


Low Tension:
Low voltage, as applied to ignition cable.


Low Loss Dielectric:
An insulation material, such as polyethylene or Teflon®, that features a relatively low level of dielectric loss.


Magnet Wire: Insulated wire intended for use in motor and transformer windings, as well as other coils for electromagnetic devices.


Magnetic Field:
A region in which a body or current experiences magnetic force.


Magnetic Flux:
The rate of flow of magnetic energy across or through a surface (real or imaginary).


Magnetic Noise:
A type of interference caused by change in current level, as in an AC power line; a magnetic field is created around the cable, and this field causes the magnetic noise.


Main Cross-Connect:
A cross-connect for first-level backbone, entrance and equipment cables.


A unit for measuring radiation dosage.


One-millionth of a farad, commonly abbreviated as “m”


One-millionth of a microfarad. (uuf, uufd, mmf, mmfd ~~.F are common abbreviations.)


A short (usually less than 30 cm.) electrical wave.


Mil : A unit – equal to one thousandth of an inch – used in measuring the diameter of a wire, or the thickness of insulation over a conductor.


Miniature Wire:
Insulated conductors of approximately 20-34 AWG.


A termination with a different impedance level than the circuit or cable it is being used with.


One of the components in the general configuration of a propagating wave front.


Simultaneous transmission of two or more messages over the same cable pair.


Mutual Capacitance:
Capacitance between two conductors, when all other conductors are connected together to shield and ground.


Myla® :
DuPont trademark for polyester film.


Nanometer (nm):
One billionth of a meter (10- 9 meter).


One billionth of a second (10- 9 seconds).


National Electric Code (NEC):
A set of regulations governing construction and installation of electrical wiring and apparatus in the United States , established by the American National Board of Fire Underwriters.


(Near-End-Crosstalk) A measurement of crosstalk which is taken at the same end as the injected primary signal.


Non volatile organic compound.


A unit of electrical resistance.


Oscillatory Surge:
A surge, which includes both positive and negative polarity values.


A very unstable molecule made from three atoms of oxygen, temporarily bonded together.


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Peak Voltage
Tell you how far the voltage swings, either positive or negative, from the point of reference.


Percentage Conductivity:
The conductivity of a material, expressed as a percentage of copper.


The uniformly spaced variations in a transmission cable’s insulation diameter, which result in reflection of a signal when its wavelength – or a multiple thereof – is equal to the distance between two diameter variations.


See Dielectric Constant.


An angular relationship between waves.


Phase Shift:
A change in the phase relationship between two alternating quantities.


Photodetector (Receiver):
A device that converts a light signal into an electrical signal.


One-millionth of one-millionth of a farad; a micromicrofarad, or picofarad (abbreviation pf). (See ~~F).


Is a computer network tool used to test whether a particular host is reachable across an IP network; it is also used to self test the network interface card of the computer. It works by sending ICMP "echo request" packets to the target host and listening for ICMP "echo response" replies. Ping estimates the round-trip time, generally in milliseconds, and records any packet loss, and prints a statistical summary when finished.


The positive or negative direction of DC voltage or current.


The orientation of a flat cable or a rectangular connector.


Power Cables:
Single or multi-conductor cables of various sizes, construction and insulation levels, designed to distribute primary power to various types of equipment.


Power Factor:
The ratio of resistance to impedance, or the ratio of an alternating current’s actual power to apparent power. Mathematically, this is defined as being the cosine of the angle between applied voltage and the resulting current.


Wiring that is installed before walls are enclosed or finished, in anticipation of future use or need.


The transformer winding which receives the energy from a supply circuit.


Primary Wiring:
A printed circuit intended to provide point-to-point electrical connections.


Propagation Delay:
Time delay between input and output of signal.


Propagation Time:
Time required for a wave to travel between two points on a transmission line.


Proximity Effect:
The non-uniform distribution of a current over a conductor’s cross-section, caused by the variation of the current in a neighboring conductor.


Pull Box:
A device to access a raceway, which is used to facilitate placing of wire or cables.


Energy that changes abruptly, from one intensity level to another. May be light energy or electrical energy.


Pulse Cable:
A type of coaxial cable constructed to transmit repeated high-voltage pulses without degradation.


The opposition offered to the flow of alternating current by inductance or capacitance of a compound or circuit.


Reflection Loss:
The part of a signal that is lost, due to reflection of power where line continuity is interrupted.


The magnetic induction that remains in a magnetic circuit after the removal of an applied magnetomotive force.


A device, which consists of a transmitter and a receiver, used to regenerate a signal to increase the system transmission length.


The measure of how difficult it is to move an electrical current through a given medium . It is measured in 52.


Resistive Conductor:
A conductor with high electric resistance.


Retractile Cord:
A cord, whose insulation or jacket is specially treated so that it will retract.


Return Wire:
A ground wire or the negative wire in a direct current circuit.


Return Loss:
The Return Loss of a line is the ratio of the power reflected back from the line to the power transmitted into the line.


Ringing Out:
Locating or identifying specific conductive paths by passing current through selected conductors.


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Segmental Conductor: A stranded conductor consisting of three or more stranded conductive elements, with each element having the approximate shape of a circle’s sector, assembled to give a substantially circular cross-section.


A layer of insulating material which is placed between a conductor and its dielectric, between a cable jacket and the components it covers, or between various components of a multiple-conductor cable.


Series Circuit:
A circuit in which the components are arranged end to end to form a single path for current.


Shared Neutral:
A connection in which a plurality of circuits use the same neutral connection. Also known as a common neutral.


Shielded Line:
A transmission line whose elements confine propagated radio waves to an essentially finite space inside a tabular conducting surface called the sheath, thus preventing the line from radiating radio waves.


Shielded-Type Cable:
A cable in which the surface of the insulation is at ground potential.


Shunt Wire:
A conductor joining two parts of an electric circuit to divert part of the current.


A current used to convey information either digital, analog, audio or video.


Sine Wave:
A wave that can be expressed as the sine of a linear function of time, or space or both.


Unbalanced, such as grounding one side of a circuit or transmission line.


Skin Effect:
The tendency of alternating current, as its frequency increases, to travel only on the surface of a conductor.


Small Form-factor Pluggable (SFP):
A specification for a new generation of optical modular transceivers. The devices are designed for use with small form factor (SFF) connectors, and offer high speed and physical compactness. They are hot-swappable. SFP transceivers are expected to perform at data speeds of up to five gigabits per second (5 Gbps), and possibly higher. Because SFP modules can be easily interchanged, electro-optical or fiber optic networks can be upgraded and maintained more conveniently than has been the case with traditional soldered-in modules. Rather than replacing an entire circuit board containing several soldered-in modules, a single module can be removed and replaced for repair or upgrading. This can result in a substantial cost savings, both in maintenance and in upgrading efforts. Several companies have formed a consortium supporting the use of SFP transceivers to meet their common objectives of broad bandwidth, small physical size and mass, and ease of removal and replacement.


(1.) In flat conductors, the distance between the reference edges of the first and last conductor. (2.) In round conductors, this defines the distance between the first and last conductors’ centers. (3.) In aerial cable, the distance between poles or support clamps.


Spark Test:
A test designed to locate pinholes in a wire or cable’s insulation, by the application of a voltage for a very short period of time, during which the wire is being drawn through an electrode field.


Standing Wave:
The stationary pattern of waves produced by two waves of the same frequency traveling in opposite directions on the same transmission line.


Standing Wave Ratio (SWR):
A figure of merit applying to transmission lines, waveguides or analogous systems, which is used to express a system’s efficiency in transmitting power.


Structural Return Loss:
The impedance caused by energy that is reflected backward, from uneven parts of a cable structure.


A temporary and relatively large increase in the voltage or current in an electric circuit or cable. Also called Transient.


The verification of frequency response by the generation of RF voltage, whose frequency is swept repeatedly through a given range at a rapid constant rate while cable response is observed.


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.


TDR (Time Domain Reflectometer):
Transmits a fast rise time pulse along the conductor. If the conductor is of a uniform impedance and properly terminated, the entire transmitted pulse will be absorbed in the far-end termination and no signal will be reflected back to the TDR. But where impedance discontinuities exist, each discontinuity will create an echo that is reflected back to the reflectometer (hence the name). Increases in the impedance create an echo that reinforces the original pulse while decreases in the impedance create an echo that opposes the original pulse. The resulting reflected pulse that is measured at the output/input to the TDR is displayed or plotted as a function of time and, because the speed of signal propagation is relatively constant for a given transmission medium, can be read as a function of cable length. This is similar in principle to radar. Because of this sensitivity to impedance variations, a TDR may be used to verify cable impedance characteristics, splice and connector locations and associated losses, and estimate cable lengths, as every non homogenity in the impedance of the cable will reflect some signal back in the form of echoes.


Telemetry Cable:
Cable used for the transmission of information from instruments to peripheral recording equipment.


Test Lead:
A flexible, insulated lead wire used for making tests, temporarily connecting instruments to a circuit, or making temporary electrical connections.


Three-Phase Current:
Current delivered through three wires, with each wire serving as a return for the other two.


Three-Phase Three-Wire System:
An alternating current supply system comprised of three conductors, over which three-phase power is sent.


Three-Wire System:
A DC system or single-phase AC system comprised of three conductors, one of which is maintained at a potential that is midway between the potentials of the other two.


TIA 568/570 Specifications:
Telecommunications Industry Association 568: The standards address commercial building cabling for telecom products and services.
570: is a cabling standard for residential telecommunications.


A means of identifying polarity.


A device for converting mechanical energy to electrical energy.


Transfer Impedance:
The ratio of the source voltage of wires inside a cable to the shield current of that cable or connected cable assembly.


Transfer of electric energy from one location to another through conductors, radiation or induction fields.


Transmission Cable:
Two or more transmission lines. See Transmission Line.


Transmission Line:
An arrangement of two or more conductors, or a waveguide used to transfer signal energy from one location to another.


Transmission Loss:
A decrease or loss in power during the transmission of energy from one point to another. Usually expressed in decibels.


Triboelectric Noise:
Noise generated in a shielded cable, due to variations in capacitance between the shield and conductor as the cable is flexed.


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UL 1436 - Outlet Circuit Testers and Similar Indicating Devices:
Portable grounded continuity testers, ground fault circuit interrupter testers, outlet-circuit testers.


UL 3111:
The latest UL standard for electrical test instruments is UL 61010B-1, which is a revision of 3111-1. It specifies the general safety requirements, such as material, design, and testing requirements, and the environmental conditions in which the standard applies. UL 3111-2-031 lists additional requirements for test probes. The requirements for hand-held current clamps, such as the current measuring portion of clamp meters, are included in UL 3111-2-032.
UL standards are gradually being harmonized with similar international standards, such as those published by IEC. Until this is completed, there may be significant differences between each group's standards. For example, IEC 61010-1 2nd Edition includes requirements for voltage-measuring instruments in CAT IV environments. UL 61010B-1 doesn't


Unbalanced Line:
A transmission line, in which voltages on the two conductors are unequal with respect to ground.


Velocity of Propagation (VP):
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 a cable’s insulation.

VOC (Volatile Organic Compound):
Organic chemical compounds that have high enough vapor pressures under normal conditions to significantly vaporize and enter the atmosphere.


A unit of electromotive force.


The term most often used in place of electromotive force, potential difference or voltage drop to designate the electric pressure that exists between two points and is capable of producing a current when a closed circuit is connected between two points.


Voltage Drop:
The voltage developed across a component or conductor by the current in the resistance or impedance of that component or conductor.


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 maximum effective voltage to minimum effective voltage, measured along the length of a mismatched radio frequency transmission line.


A voltmeter, also known as a voltage meter, is an instrument used for measuring the potential difference, or voltage, between two points in an electrical or electronic circuit. Some voltmeters are intended for use in direct current (DC) circuits; others are designed for alternating current (AC) circuits. Specialized voltmeters can measure radio frequency (RF) voltage.


Volume Resistivity (Specific Insulation Resistance):
The electrical resistance between opposing faces of a 1 cm. cube of insulating material, commonly expressed in ~/centimeter.


A unit of electric power.


Wave Form:
A graphical representation of a varying quantity. Usually, time is represented on the horizontal axis, and the current or voltage value is represented on the vertical axis.


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.


Wire Gauge:
A system of numerical designation of wire sizes.


Test used to identify physical errors of the installation; proper pin termination at each end, shorts between any two or more wires, continuity to the remote end, split pairs, crossed pairs, reversed pairs, and any other mis-wiring.


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