Terms Glossary


A A symbol designation for ampere.
AC Alternating current.
AHJ Authority Having Jurisdiction.
ALL-CALL The capability for one or more intercom stations to place an intercom call to all of the other stations on the system (capable of receiving an all-call) simultaneously.
AMERICAN WIRE GAUGE (AWG) A standard for expressing wire diameter. As the AWG number gets smaller, the wire diameter gets larger.
AMP (AMPERE) A standard unit of electrical current. Defined as the amount of current that flows when one volt of electromotive force is applied across one ohm of resistance.
ANNUNCIATION The activation of a lighted or mechanical indictor (annunciator) when a remote switch or device has been activated.
ANNUNCIATOR A device that indicates by a lighted or mechanical indictor, when a remote switch or device has been activated.
ANSI American National Standards Institute. Usually used to define hardware or electrical standards.
ATTENUATION The decrease in magnitude of a signal as it travels through any transmitting medium, such as a cable or circuitry. Attenuation is measured as the logarithm of a ratio. It is expressed in decibels or dB.
AUDIO A term used to describe sounds within the range of human hearing. Also used to describe devices which are designed to operate usually within this range (20 Hz to 20 kHz).
AUDIO FREQUENCY Frequencies within the range of human hearing: approximately 20 to 20,000 Hz.
AWG American Wire Gauge. A wire diameter specification. The smaller the AWG number, the larger the wire diameter.


BALANCED LINE A cable having two identical conductors which carry voltages opposite in polarity and equal in magnitude with respect to ground, suitable for differential signal transmission.
BANDWIDTH The difference between the upper and lower limits of a given band of frequencies. Expressed in Hertz.
BAUD Unit of data transmission speed meaning bits per second (300 baud=300 bits per second).
BIT One binary digit (0 or 1). Eight (8) bits equals one (1) byte.
BITS PER SECOND The number of binary bits that can be transmitted per second - I.e. Mbps (Mega - millions), Gbps (Giga - billions).
BNC Abbreviation for "Bayonet Neil Concelman". A twist-lock coaxial cable connector used extensively in video and Radio Frequency applications. It is named for its inventor.
BOOSTER A device or amplifier inserted into a line or cable to increase the voltage. Transformers may be employed to boost ac voltages.
BPS The number of binary bits that can be transmitted per second - I.e. Mbps (Mega - millions), Gbps (Giga - billions).
BRAID A group of textile or metallic filaments interwoven to form a tubular flexible structure which may be applied over one or more wires, or flattened to form a strap.


C Symbol designation for capacitance, and Celsius temperature measurement.
CABLE A group of individually insulated conductors inside a common jacket.
CANADIAN ELECTRICAL CODE (CEC) Canadian version of the US National Electrical Code (NEC).
CAPACITANCE The ability of a dielectric material between conductors to store energy when a difference of potential exists between the conductors. The unit of measurement is the farad. Cable capacitance isusually measured in picofarads (pF).
CAPACITIVE CROSSTALK Cable crosstalk or interference resulting from the coupling of the electrostatic field of one conductor upon one or more others.
CAPACITOR An electronic component consisting of two conducting surfaces separated by a dielectric material. The capacitance is determined by the area of the surfaces,type of dielectric, and spacing between the conducting surfaces.
CATV Abbreviation for Community Antenna Television (aka Cable TV).
CCTV Closed-circuit television (video).
CIRCUIT A network of conducting media designed to pass an electric current.
COAXIAL CABLE (COAX) A cylindrical transmission line consisting of a conductor centered inside a metallic tube or shield, separated by a dielectric material, and usually covered by an insulating jacket. Usually used to transmit video signals.
CODE BLUE A term typically used to indicate the highest medical emergency situation in a hospital or health care facility. It is derived from the concept of a person turning 'Blue' from lack of oxygen or another emergency. It is also called Code Call or Code 99.
COIL CORD A cord having specially treated insulation or jacket so that it will retract like a spring.
COLOR CODE A system of different colors or stripes used to identify components of cables such as individual conductors or groups ofconductors.
COMMON TALK An intercom system using handset type stations where any one handset that is lifted off of its cradle is connected to a common talk (party line) circuit, without privacy. A Common Talk circuit usually allows for conference call capabilities as well.
COMMON WIRES Refers to one or more wires that are run in parallel (in common) to multiple intercom or video-intercom stations. Usually refers to the main (trunk) power or control wires on a system.
COMPOSITE VIDEO The encoded output of a camera, video tape recorder, etc., whereby the red, green, blue, horizontal and vertical sync are transmitted simultaneously down one cable.
CONDUCTOR A substance, usually metal, used to transfer electrical energy from one point to another.
CONDUIT A tube of metal or plastic through which wire or cable can be run. Used to protect the wire or cable and, in the case of metal conduit, make it fireproof and to minimize interference.
CONNECTOR A mechanical device designed to allow electrical flow from one wire or cable to a device on another cable.
CORD A very flexible insulated cable or string.
CPE Central Processing Equipment. Usually refers to a computerized central control unit uusing microprocessor or microcontroller circuitry.
CPS Abbreviation for cycles per second (or Hertz). Frequency.
CPU Central Processing Unit. Usually refers to a computerized central control unit using microprocessor or microcontroller circuitry.
CROSSTALK A type of interference caused by audio frequencies from one pair of conductors being coupled into adjacent pairs.
CRT Cathode Ray Tube. A conventional TV (video) screen.
CSA Abbreviation for Canadian Standards Association, the Canadian version of the Underwriters Laboratories (UL).


DB Decibel. A unit of measure of sound level.
DC Direct current.
DECIBEL (DB) Decibels are also used to express acoustic power, such as the apparent level of a sound. The decibel can express an actual level only when comparing with some definite reference level that is assumed to be zero dB.
DESK MOUNT(ING) A method to allow a station to sit on, or mount to a desktop or table top, usually using a sloped cabinet or housing.
DIELECTRIC An insulating (non-conducting) medium when used in a signal-carrying design.
DIGITAL SIGNAL An electrical signal which possesses two distinct states (on/off, positive/negative).
DISTORTION Any undesired change in a wave form or signal.
DISTORTION Any undesired change in a wave form or signal.
DOOR OPENER An electro/mechanical device used to remotely allow a locked door to open.
DOOR RELEASE See Door Opener.
DOOR STRIKE See Door Opener.


EARTH British terminology for zero-reference ground.
EIA Electronic Industries Association (formerly RMA or RETMA).
ELECTROMAGNETIC Referring to the combined electric and magnetic fields caused by electron motion through conductors.
ELECTROMAGNETIC COUPLING The transfer of energy by means of a varying magneticfield. Inductive coupling.
ELECTROSTATIC Pertaining to static electricity, or electricity atrest. An electric charge, for example.
EMI Abbreviation for electromagnetic interference.
EMT Electro-metallic tubing. A form of metallic pipe or conduit.


F Frequency. Also Fahrenheit temperature measurement.
FAIL SAFE Usually used to refer to a type of door opener. When power is 'OFF', the device is unlocked or unlatched.
FAIL SECURE Usually used to refer to a type of door opener. When power is 'OFF', the device is locked or latched (or secure).
FARAD A unit of capacity that will store one coulomb of electrical charge when one volt of electrical pressure is applied.
FEEDBACK An overload to an audio circuit usually caused by the audio output being too close to the audio input.
FIBER OPTICS Light transmission through optical fibers for communication and signaling.
FLAME RESISTANCE The ability of a material not to fuel a flame once the source of heat is removed.
FLAT CABLE Also referred to as planar and/or ribbon cable. Any cable with two or more parallel conductors in the same plane encapsulated by insulating material.
FLOATING Referring to a circuit which has no connection to ground.
FLUSH MOUNT(ING) Usually refers to making a cut-out or opening in the wall to allow the internal components (guts) of a station to fit inside the finished wall.
FM Frequency modulation. Usually refers to a range of radio frequencies.
FREQUENCY The number of times a periodic action occurs in one second. Measured in Hertz.
FREQUENCY RESPONSE The characteristic of a device denoting the range of frequencies over which it may be used effectively (i.e. 20 to 20,000 Hz).


GAUGE The physical diameter of a wire. A standard for expressing wire diameter. As the AWG number gets smaller, the wire diameter gets larger.
GIGA One billion.
GIGAHERTZ (GHZ) A unit of frequency equal to one billion hertz.
GND Ground or Electrical Ground.
GROUND An electrical connection between a circuit and the earth. Also refers to a conductor connected to earth. In some instances, can refer to a central metallic point designated as having "zero" potential.
GROUND CONDUCTOR A conductor in a transmission cable or line that is grounded.
GROUND LOOP An undesirable circuit condition in which interference is created by ground currents when grounds are connected at more than one point.
GROUND POTENTIAL The potential of the earth. A circuit, terminal, or chassis is said to be at ground potential when it is used as a reference point for other potentials in the system.


HANDS-FREE REPLY Ability to reply to a voice call from an intercom station, without having to press any buttons or controls.
HARNESS A group of cables, usually with many breakouts with the wire ends prepared for termination or terminated to connectors and ready to install.
HERTZ (HZ) The number of changes in polarity which a signal makes in one second. An indication of frequency. Also referred to as cycles-per-second.
HOME RUN WIRES See Selective Wires.
HORIZONTAL MAILBOX(ES) Multi unit mailboxes with deep 'horizontal' doors/compartments. They are also referred to as 'pidgeon hole' mail boxes. Horizontal mailboxes take up a less wall space (width), but they require a wall depth of up to 18". They are usually used in larger buildings.
HUM A term used to describe the 60- or 120 cycle per second noise present in the sound of some communications equipment. Usually hum is the result of undesired coupling to a 60 cycle source or to the defective filtering of 120 cycle ripple output of a rectifier.


IBC International Building Code.
IMPEDANCE The resistance that a circuit offers to the flow of alternating current or any other varying current at a particular frequency. It is measured in ohms.
IMPEDANCE, HIGH Generally, the area of 25,000 ohms or higher.
IMPEDANCE, LOW Generally, the area of 1 through 600 ohms.
INDUCTANCE The property of wire which stores electrical current in a magnetic field around the wire. By coiling wire, the effect can be intensified. It is measured in Henrys.
INDUCTION The phenomenon of a voltage, magnetic field, or electrostatic charge being produced in an object by lines of force from the source of such fields.
INDUCTIVE CROSSTALK Crosstalk resulting from the coupling of the electromagnetic field of one conductor upon another.
INPUT A signal (or power) which is applied to a piece of electric apparatus or the terminals on the apparatus to which a signalor power is applied.
INSULATION A material having good dielectric properties which is used to separate close electrical components, such as cable conductors and circuit components.
INTERFACE The region where two systems or a major and a minor system meet and interact with each other.
INTERFERENCE Disturbances of an electrical or electromagnetic nature that introduce undesirable responses into other electronic equipment.
ISO International Standards Organization.
ISOLATION The ability of a circuit or component to reject interference, usually expressed in dB.


JACKET Pertaining to wire and cable, the outer protective covering (may also provide additional insulation).
JUMPER A short length of conductor or flat cable used to make a connection between terminals or around a break in a circuit, or between circuit boards.


KEY KEEPER A key keeper is basically a lock box into which a key to the building entrance door is stored. It allows the building owner to comply with the USPS regulations requiring that the letter carrier be allowed entry to a locked building lobby, without the need to bother any of the tenants. The letter carrier uses his/her regular mailbox key to open the key keeper and retrieve the building key. Key Keepers are also made with a pushbutton (instead of the key) to allow the letter carrier to electrically release the building entrance door.
KILO One thousand (metric measurement).


LAN A data network connecting any number of users, intended to serve a small area. Local Area Network.
LASER A coherent source of light with a narrow beam and a narrow spectral bandwidth (about 2nm).
LAY 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. In a twisted pair cable, the lay length is the distance it takes for the two wires to completely twist around each other.
LEAKAGE The undesirable passage of current over the surface of or through an insulator.
LIGHT EMITTING DIODE (LED SOURCE) A semiconductor device that emits incoherent light formed by the P-N junction. Light intensity is roughly proportional to electrical current flow.
LINE LEVEL Refers to the output voltage level of a piece of electronic equipment. Usually expressed in decibels (e.g. 0dBv).
LINE VOLTAGE The value of the potential existing on a supply or powerline.
LOAD A device that consumes power from a source and uses that power to perform a function.
LOCAL AREA NETWORK (LAN) A data network connecting any number of users, intended to serve a small area.
LOOP WIRING A method of running a cable with multiple conductors, looped (in parallel) from one location to the next.
LOSS Energy or signal lost without accomplishing useful work.
LOSSY Having poor efficiency.
LOW FREQUENCY A band of frequencies extending form 30 to 300 kHz in the radio spectrum, designated by the Federal Communications Commission (FCC).
LUMINANCE SIGNAL The portion of the composite video signal that represents the brightness or the black and white information.


M Mutual inductance. The abbreviation for mega or 1 million. And also indicates 1000 (one thousand) feet in the wire industry. m=abbreviation for milli or one-thousandth.
MA milliampere (one-thousandth of an ampere).
MAG LOCK An electro mechanical device used to hold a door closed, by means of an electro-magnet, until the electrical power holding the door closed has been de-activated, usually from a remote location.
MASTER (A.K.A. MASTER STATION) An intercom station which typically can place a voice call to any other intercom station on the system.
MATV Abbreviation for Master Antenna Television.
MBPS Mega bits per second - the number of bits, in millions, transmitted per second.
MEGA Prefix meaning million.
MEGAHERTZ (MHZ) Unit of frequency equal to one million hertz (one million hertz per second).
MFD Microfarad (one-millionth of a farad).
MICRO Prefix meaning one-millionth.
MICROFARAD One-millionth of a farad (uf, ufd, mf, and mfd are common abbreviations).
MICROPHONICS Noise caused by mechanical excitation of a system component. In a single-conductor microphone cable, for example, microphonics can be caused by the shield rubbing against the dielectric as the cable is flexed.
MIL A unit of length equal to one thousandth of an inch(.001").
MILLI Prefix meaning one-thousandth (metric measurement).
MODE A single electromagnetic wave traveling in an optical fiber. Also, condition in reference to equipment and its state.
MODEM Device that converts signals in one form to another form compatible with another kind of equipment. Modulator/De-modulator.
MODULATION Altering the characteristics of a carrier wave to convey information. Modulation techniques include amplitude frequency, phase, plus many other forms of on-off digital coding.
MORTISE A term usually used in the hardware industry to refer to a cutout in a piece of wood or metal made in the shape of a projecting part shaped to fit the 'mortised' opening.
MULTIPLEX A technique for putting two or more signals into a single channel.
MV Millivolt (one-thousandth of a volt).
MW Milliwatt (one-thousandth of a watt).
MYLAR DuPont trademark for polyethylene terephtalate (polyester) film.


NANO One-billionth.
NATIONAL ELECTRICAL CODE (NEC) A publication of the National Fire Protection Association (NFPA) which outlines requirements for electrical wiring andbuilding construction. Also called the NEC.
NEC A publication of the National Fire Protection Association (NFPA) which outlines requirements for electrical wiring and building construction. Also called the NEC.
NEMA National Electrical Manufacturers Association.
NETWORK A network is a method of data communications between computers.
NFPA National Fire Protection Association.
NOISE In a cable or circuit, any extraneous signal which tends to interfere with the signal normally present in or passing through the system.
NON-PLENUM Area that a cable can be installed in a building that is not used for air return.
NOTCH The removal of the web section between conductors of a flat cable to aid in stripping, slitting, and termination.
NTSC Organization that formulated standards for the current American television system. Also describes the system of color telecasting which is used in Japan, Thailand and parts of South America. NTSC television uses a 3.579545 MHz subcarrier whose phase varies with the instantaneous hue of the televised color and whose amplitude varies with the instantaneous saturation of the color. NTSC employs 525 lines per frame, 30 frames per second and 59.94 fields per second.
NYLON An abrasion-resistant thermoplastic with good chemical resistance.


OHM The unit of electrical resistance. The value of resistance through which a potential difference of one volt will maintain a current of one ampere.
OUTPUT The useful power or signal delivered by a circuit or device.


PAL (PHASE ALTERNATE LINE) PAL is a European color TV system featuring 625 lines per frame, 25 frames and 50 fields per second. Used mainly in Europe, China, Malaysia, Australia, New Zealand, the Middle East, and parts of Africa. PAL-M is a Brazilian color TV system with 525 lines per frame, 30 frames and 60 fields per second.
PARALLEL CIRCUIT A circuit in which the identical voltage is presented to all components, with current dividing among the components according to the resistances or the impedances of the components.
PARALLEL DIGITAL Digital information that is transmitted in parallel form. Often used informally to refer to parallel digital television signals.
PATCHCORD A flexible piece of cable terminated at both ends with plugs. Used for interconnecting circuits on a patchboard.
PEAK The maximum instantaneous value of a varying current orvoltage.
PEDESTAL MAILBOX(ES) Multi unit mailboxes mounted on a secure pedestal for outdoor use. Typically used in condominium and gated communities. The doors/compartments are similar to 'horizontal' style mailboxes. They are also referred to as 'cluster' mailboxes or NDCBU's.
PHASE An angular relationship between waves.
PHASE SHIFT A change in the phase relationship between two alternating quantities.
PICKUP Any device which is capable of transforming a measurable quantity of intelligence (such as sound) into relative electrical signals (e.g., a microphone).
PICO One-trillionth.
PICOFARAD One billionth of a farad. A micromicrofarad. Abbreviation pF or mmF.
PLANAR CABLE Also referred to as flat and/or ribbon cable. Any cable with two or more parallel conductors in the same plane encapsulated by insulating material.
PLASTIC High polymeric substances, including both natural and synthetic products that are capable of flowing under heat and pressure, called thermoplastics. Unlike rubber and other thermoset compounds, plastics can be remelted and reused.
PLENUM A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.
PLUG A male housing with male or female contacts.
POINT WIRES See Selective Wires.
POLARIZATION The orientation of a flat cable or a rectangular connector. e.g., for gray flat cable, the colored edge indicating the number one conductor.
POLYPROPYLENE A thermoplastic similar to polyethylene but stiffer and having a higher softening point (temperature). This material is primarily used as an insulation material. Typically, it is harder than polyethylene. This makes it suitable for thin wall insulations. The dielectric constant is 2.25 for solid and 1.55 for cellular designs.
POLYURETHANE (PUR) Broad class of polymers noted for good abrasion and solvent resistance. Can be in solid or cellular form. This thermoplastic material is used primarily as a cable jacket material. It has excellent oxidation, oil, and ozone resistance. Some formulations also have good flame resistance. It is a hard material with excellent abrasion resistance. It has outstanding "memory" properties, making it an ideal jacket material for retractile cords.
POLYVINYL CHLORIDE A general purpose thermoplastic used for wire and cable insulation and jackets. Also known as PVC.
POSTAL APPROVED Refers to equipment that has been submitted to the US Postal Service (USPS) and approved by the USPS as having met certain USPS requirements and regulations.
POSTAL RELEASE An electro-mechanical switch built-into a piece of equipment that, when activated, electrically releases the door release mechanism at an entrance to a building to allow a USPS letter carrier to gain access to the building.
POWER The amount of work per unit of time. Usually expressed in watts and equal to the formula for power in watts. (I to the second power times R).
POWER LOSS The difference between the total power delivered to a circuit, cable, or device and the power delivered by that device to a load.
POWER RATIO The ratio of power appearing at the load to the input power. Expressed in dB.
PRIVACY An intercom option that allows a station to be called, but the voice response is blocked unless the recipient releases the privacy switch or function.
PUSHBUTTON An electro-mechanical device which, when activated, makes and/or breaks an electrical connection. Usually activated by a mechanical 'push' action.
PUTUP Packaging of finished wire or cable. Length of wire or cable on a spool or in a carton or box.
PVC Polyvinyl chloride. Sometimes referred to as vinyl. Fire resistant.


QUAD A four conductor cable. Also called "starquad". Usually used in phone system wiring.


RADIO FREQUENCY (RF) Radio-frequency. Usually considered to be frequenciesranging from 1 MHz to 3GHz.
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.
RECEPTACLE A female housing with male or female contacts.
RECESSED MOUNT(ING) See flush mount(ing).
RECTIFIER An electronic component used to convert alternating current (AC) to direct current (DC).
REFLECTION The change in direction (or return) of waves striking a surface. For example, electromagnetic energy reflections can occur at animpedance mismatch in a transmission line, causing standing waves.
REMOTE (A.K.A. REMOTE STATION) An intercom station which typically can answer a voice call from a master station. Remote stations may be equipped with one or more call buttons for tone and/or visual signalling only to one or more master stations. Also commonly referred to as ‘sub station’ or 'slave station'.
REPEATER A receiver and transmitter combination used to regenerate an attenuated signal.
RESISTANCE In dc circuits, the opposition a material offers to current flow, measured in ohms. In ac circuits, resistance is the real component of impedance, and may be higher than the value measured at dc.
RESONANCE An ac circuit condition in which inductive and capacitive reactances interact to cause a minimum or maximum circuit impedance.
RETRACTILE CORD A cord having specially treated insulation or jacket so that it will retract like a spring. Retractibility may be added to all or part of a cord's length.
R-F Radio-frequency.
RFI Abbreviation for Radio Frequency Interference.
RG/U "RG" is the abbreviation for "radioguide," a military designation for a coaxial cable, and "U" stands for "universal."
RGB Abbreviation for the three parts of color video signal: red, green and blue, and also refers to multi-coaxial cables carrying these signals.
RIBBON CABLE A flat cable made with parallel round conductors in the same plane. Also referred to as planar and/or flat cable. Any cable with two or more parallel conductors in the same plane encapsulated by insulating material.
RIM (CYLINDER) A term usually used in the hardware industry to refer to a type of lock mechanism that fits into a latch mechanism that fits onto the surface of the door frame and is not cut-in.
RINGING OUT The process of locating or identifying specific conductor paths by means of passing a current through selected conductors.
RISER A cable run used to connect a group of intercom or video-intercom stations. Most commonly referred to in apartment systems where cables are run in vertical risers/lines.
RJ17C (RJ-17C) Telecommunications interface connector, consisting of 12 sets of phone contacts. Usually used in 'No-Phone-Bill' or 'No-Phone-Line' type telephone entry systems.
RJ45 (RJ-45) Modular telecommunications connector, consisting of 8 contact points.


SELECTIVE CALLING Ability to call a specific station (by voice and/or audible signal) by dialing a keypad or pressing the station’s individual selector (call) button.
SELECTIVE WIRES Refers to one or more wires that (typically) are run individually and directly from a remote station to a master station that individually identifies that remote station or allows signaling or communication directly with that remote station.
SEMICONDUCTOR In wire industry terminology, a material possessing electrical conductivity that falls somewhere between that of conductors and insulators. Usually made by adding carbon particles to an insulator. Not the same as semiconductor materials such as silicon, germanium, etc. Used for making transistors and diodes.
SEPARATOR Pertaining to wire and cable, a layer of insulating material such as textile, paper, Mylar, etc., which is placed between a conductor and its dielectric, between a cable jacket and the componentsit covers, or between various components of a multiple-conductor cable. It can be utilized to improve stripping qualities, flexibility, or can offer additional mechanical or electrical protection to the components it separates.
SERIES CIRCUIT A Circuit in which the components are arranged end to end to form a single path for current.
SHEATH Pertaining to wire and cable, the outer protective covering (may also provide additional insulation).
SHIELD A tape, serve or braid (usually copper, aluminum, or other conductive material) placed around or between electric circuits or cables or their components, to prevent signal leakage or interference.
SHIELD COVERAGE The optical percentage of a cable actually covered by shielding material.
SHIELD EFFECTIVENESS The relative ability of a shield to screen out undesirable interference. Frequently confused with the term shield coverage.
SHIELD PERCENTAGE The percentage of physical area of a circuit or cable actually covered by shielding material.
SIGNAL Any visible or audible indication which can convey information. Also, the information conveyed through a communication system.
SIGNAL CONDUCTOR A conductor in a transmission cable or line that carries electrical signals.
SILICONE General Electric trademark for a material made from silicone and oxygen. Can be in thermosetting elastomer or liquid form. The thermosetting elastomer form is noted for high heat resistance. This is a very soft thermoset insulation. It has excellent electrical properties plus ozone resistance, low moisture absorption, weather resistance, and radiation resistance. It typically has low mechanical strength and poor scuff resistance.
SNR Signal to Noise Ratio. Commonly used interchangeably with ACR - the difference between attenuation and crosstalk, measured in dB, at a given frequency (acronym for Attenuation Crosstalk Ratio). Important characteristic in networking transmission to assure thatsignal sent down a twisted pair is stronger at the receiving end of the cable than are any interference signals imposed on that same pair by crosstalk from other pairs.
SOURCE The device (usually LED or laser) used to convert an electrical information-carrying signal into a corresponding optical signal for transmission by an optical wave guide.
SPACING The distance between the centers of two adjacent conductors. Pitch.
STP Shielded Twisted Pair(s).
STRAND A single uninsulated wire.
STRANDED CONDUCTOR A conductor composed of groups of uninsulated wires.
STRIP To remove insulation from a cable or wire.
SURFACE MOUNT(ING) Usually refers to affixing or mounting a station right onto the finished wall, without any of the internal components (guts) protrude back into the wall.
SURGE A temporary and relatively large increase in the voltageor current in an electric circuit or cable. Also called transient.
SVHS Abbreviation for super VHS. A video format in which the two parts of the VHS video signal, the chrominance and luminance, are transmitted separately providing for better picture resolution with less noise.
SWITCH An electro-mechanical device which, when activated, makes and/or breaks an electrical connection.


TEFLON (R) DuPont Company trademark for fluorocarbon resins. (FEP -Fluorinated ethylene-propylene. A thermo-plastic material with good electrical insulating properties and chemical and heat resistance). (TFE- Tetrafluoroethylene. A thermoplastic material with good electrical insulating properties and chemical and heat resistance.). It is not suitable where subjected to nuclear radiation and does not have good high voltage characteristics. The cost of Teflon is approximately 8 to 10 times more per pound than PVC compounds.
TEMPERATURE RATING The maximum temperature at which the insulating material may be used in continuous operation without change of its basic properties.
TENSILE STRENGTH The pull stress required to break a bare wire.
test test
THERMAL RATING The temperature range in which a material will perform its function without undue degradation.
TIA Telecommunications Industry Association. Body which authored the TIA/EIA 568A "Commercial Building Telecommunications Wiring Standard" in conjunction with EIA.
TONE SIGNAL An audible sound (tone) produced by the oscillating of a speaker, generated when an intercom station wishes to signal another station by non-verbal means.
TRANSDUCER A device for converting mechanical energy to electrical energy.
TRANSFORMER An electrical device for transferring AC current from one voltage to another. Most intercom applications operate at low voltage, and require a 'step down' transformer to reduce voltage to system specifications (usually 16 or 24 volts).
TRANSMITTER An electrical component used to convert an audible input to a variety of electrical signals.
TWISTED PAIR Two lengths of insulated conductors twisted together around themselves.


UHF Abbreviation for ultra high frequency, 300 to 3,000 MHz.
UL Abbreviation for Underwriters Laboratories, a non-profit organization which tests and verifies construction and performance of electronic parts and equipment, including wire and cable.
UL LISTED When a device has been submitted to and tested by UL and meets a specific UL Standard, it receives a UL Listing, indicating it meets that UL standard. There is no such thing as a device that is 'UL Approved'.
UNBALANCED LINE A transmission line in which voltages on the two conductors are unequal with respect to ground. A coaxial cable is a common type of unbalanced line.
USPS Unites States Postal Service.
UTP Unshielded Twisted Pairs(s).


V Volt.
VA Volt-ampere. A designation of power in terms of voltage and current.
VERTICAL MAILBOX(ES) Multi unit mailboxes with tall 'vertical' doors/compartments. Vertical mailboxes are the least expensive type of mail box, but tend to take up a lot of wall space (width). They are usually used in smaller buildings.
VHF Abbreviation for very high frequency, 30 to 300 HMz as designated by the Federal Communications Commission.
VHS Abbreviation for Video Home System. VHS is a trademark of Panasonic, Inc.
VIDEO Pertaining to picture information in a television system.
VLF Abbreviation for very low frequency, 10 to 30 kHz.
VOLT A unit of electromotive force.
VOLTAGE Electrical potential of electromotive force expressed in volts.
VOLTAGE DROP The voltage developed across a component or conductor by the current flow through the resistance or impedance of the component orconductor.
VOLTAGE RATING The highest voltage that may be continuously applied to a cable construction in conformance with standards or specifications.


W Symbol for watt or wattage.
WATT A unit of electrical power.
WIRE A conductor, either bare or insulated.


XLR A multi-pin audio Connector (typically 3 pins) used in microphone, line level and snake cable connections.


Z Symbol for impedance (ohms).

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