earth current - Alternating or direct current that flows in the earth whether momentary, intermittent, or continuous.

earth curvature - (earth bulge) The curvature of the Earth and its affect on lineof-sight communications links that are more than 10 km (6.2 mi) apart.

earth ground - An electrical connection to earth obtained by a grounding electrode system. See also approved ground and ground.

earthing - See grounded.

earthing electrode - See grounding electrode.

earth potential rise (EPR) - See ground potential rise.

earth resistance test - The testing of earth electrodes and the measurement of soil resistivity.

easement - A right acquired by one party to use land belonging to another party for a specific purpose. edge The point at which the enterprise network intersects with the Internet service provider network.

edge device - 1. A device designed to connect the enterprise network with an Internet service provider (ISP) network, generally owned by the ISP. 2. A device designed to transfer data between a local network (e.g., Ethernet or token ring) and an internetwork that uses a different technology (e.g., asynchronous transfer mode).

edge site - Generally, a small office connected to a network operation center or headquarters via an Internet service provider network. Also called a remote or branch site.

effective ground - Intentional connection to earth through a ground connection or connections of sufficiently low impedance (whose value is specified in suitable grounding/earthing/bonding standards) and having sufficient current-carrying capacity to prevent the buildup of voltages that may result in undue hazards to connected equipment or to persons. (NEC)

effective isotropic radiated power (EIRP) - The arithmetic product of the power supplied to an isotropic (ideal [imaginary] spherical omnidirectional) antenna and its gain.

effective radiated power (ERP) - The power supplied to an antenna multiplied by the antenna gain in a given direction.

egress - A point of exit from a building or property.

elastomeric - Characteristic of a material or substance allowing stretching and or flexibility, resembling rubber or elastic.

elastomeric firestop - A flexible firestopping material resembling rubber.

electrical closet - Floor-serving facility for housing electrical equipment, panel boards, and controls. (TIA)

electrical coupling - 1. The transfer of energy between two circuits due to electric field. This coupling can be represented by a capacitor. This effect also is called capacitive coupling. In telecommunications cables, this is due to the mutual capacitance of its conductors. 2. The transfer of energy between two or more electrically conducting bodies. This energy can be through a direct connection or an indirect connection (e.g., electromagnetic interference/radio frequency interference). Also called electric field coupling.

electrical distribution panel (EDP) - An assembly, mounted in or on a wall and accessible only from the front, consisting of enclosures, buses, and switches to control light, heat, or power circuits.

electrical drawing - Two-dimensional graphical representation of the electrical components of a construction project (e.g., power distribution, lighting).

electrical-magnetic coupling - The transfer of energy, through an indirect magnetic connection, between any two electrical conducting bodies. For differences, see harmonic coupling.

electrical metallic tubing (EMT) - Thinwail metal tubing that does not have threaded ends, which is widely used in electrical distribution systems and as a pathway for telecommunications cabling.

electrical noise - Unwanted voltage or current, or both, that appears in an electrical system. For given system characteristics, electrical noise may impair proper functioning.

electrical service equipment - That portion of the electrical power installation, the service enclosure or its equivalent, up to and including the point at which the supply authority makes connection. (TIA)

electric field strength - A vector quantity fully described when its magnitude and direction are given. Electric field is expressed in volts per meter, and the direction of the electric field at each point in space is that in which a positive electric charge placed at that point will move. See also voltage gradient.

electric latch retraction - Allows doors equipped with exit devices to be operated in push-pull (dogged) mode by electrically retracting the latch bolts.

electric lockset - An electrified version of a standard lockset that generally comes in two basic configurations. Available products incorporate an actuating solenoid that locks or unlocks a lockset, duplicating or replacing the function of a traditional mechanical key.

electric strike - An electrified locking element that replaces a traditional doors fixed strike with an electromechanical unit that upon application (fail secure) or removal (fail-safe) of power, a solenoid electrically activates the keeper, allowing a lock's latch bolt to pass.

electromagnetic compatibility (EMC) - The ability of the design and operation of equipment in a manner that makes them immune to certain amounts of electromagnetic interference, while keeping the interference generated by them within specific limits.

electromagnetic coupling - The ability of an electrical circuit to indirectly connect to another circuit through the magnetic field transfer of energy (electromagnetic interference) or radio frequency (radio frequency interference) energy transfer from one conductor to another.

electromagnetic disturbance - Any electromagnetic occurrence that may degrade the performance of a device, unit of equipment, or system. An electromagnetic disturbance may be noise, an unwanted signal, or a change in the propagation medium.

electromagnetic emission - The phenomenon by which electromagnetic energy emanates from a source. Emissions can be either radiated or conducted when coupled into a given disturbed circuit. Such emissions may be divided into two categories: intentionally emitted signals and unintentional electromagnetic emissions. See also emission.

electromagnetic environment - The electromagnetic field existing in a transmission medium.

electromagnetic field tester - Measures the presence of electromagnetic interference.

electromagnetic field (EMF) - The energy field radiating from a source and containing both electric and magnetic field components. An electric field is a field surrounding a charged object. A magnetic field is the field surrounding any current-carrying conductor.

electromagnetic immunity - The ability of a device, equipment, or system to perform without degradation in the presence of an electromagnetic disturbance.

electromagnetic induction - Current flow in telecommunications conductors produced by coupling of a magnetic field (e.g., by current in power lines, the cable shield, or other cable pairs).

electromagnetic interference - EMQ Radiated or conducted electromagnetic energy that has an undesirable effect on electronic equipment or signal transmissions. (TIA)

electromagnetic lock - An electric lock that uses an electromagnet to hold a door closed.

electromagnetic radiation - (EMR) Radiation made up of oscillating electric and magnetic fields and propagated with the speed of light. Includes gamma radiation, X rays, ultraviolet, visible, and infrared radiation, radar, and radio waves.

electromagnetic spectrum - The full range of electromagnetic emissions, which includes all light and radio waves.

electromagnetic susceptibility - The inability of a device, equipment, or system to resist an electromagnetic disturbance.

electromagnetic wave - A wave produced by the interaction of time-varying electric and magnetic fields.

electromotive force (EMF) - The maximum potential difference between two electrodes of a galvanic or voltaic cell, commonly referred to as voltage.

electronic access control - A system composed of computer software and hardware for managing access to identified spaces through the use of established security levels, issued credentials, and peripheral electronic hardware, including door contacts, request to exit devices, card readers, and electronic locking hardware.

Electronic Industries Alliance (EIA) - An alliance organized along specific electronic product and market lines, and, as a standards association, develops and publishes industry guidelines.

electronic serial number (ESN) - A unique 32-bit serial number permanently stored in the mobile station or cellular equipment by the manufacturer. The ESN is transmitted during the authentication process.

electronic switching system (ESS) - A digital electronic technology used for centralized voice systems.

electrostatic coupling - The induction of electrical charges in electrical conductors that may be the result of capacitive coupling from the electric field (e.g., of a nearby power line).

electrostatic discharge (ESD) - Electrical release of static electricity generated by interaction of dissimilar materials.

electrostatic field - Space in which there is electric stress produced by static electric charges.

electrostatic induction - Induced currents in electrical conductors as a result of the coupled voltage due to capacitive coupling (by electric field) of a riearby electric line.

elevation drawing - A two-dimensional graphical representation of a vertical plane (side view).

emergency power - A stand-alone secondary electrical supply source not dependent upon the primary electrical source. (TIA)

emission - The phenomenon by which electromagnetic energy emanates from a source. Emission can be either radiated or conducted. Such emissions may be divided into two categories: intentionally emitted signals and unintentional electromagnetic emissions.

emulation - The technique of modifying a device with hardware or software to make it operate in the same manner as another device. See also terminal emulation.

encapsulant - A permanent or removable filling compound for a splice enclosure to prevent water intrusion.

encapsulation - 1. A process that enables message transfer over dissimilar networks. It is used when messages initiated by network devices must be transported over an intermediate network using different protocols. The encapsulation process places messages into data frames compatible with the intermediate network without altering the message content. Upon arrival at the destination network, the reverse process is used to extract the original form of the message. 2. The process of installing permanent or removable filling compound. See also encapsulant.

enclosure - A case or housing for equipment, cable terminations, and cross-connect cabling. (TIA)

encoding - The process of writing data to a card. See also signal encoding

encroachment - The private use of another person's right-0f-way for an indefinite term, with or without permission, usually involving obstructions (man-made structures).

encroachment permit - A legal document (usually issued by a government agency) that gives the permit holder permission to install and maintain facilities over or under the property designated by the permit.

encryption - 1. A security mechanism that transforms readable data content into a seemingly random collection of characters, numbers, and/or symbols to provide confidentiality. 2. A modification of a bit stream to make it appear random and to control emissions (e.g., direct sequence spread spectrum).

encryption key - See key.

encumbrance - Any lien, claim, or liability attached to the land that affects or limits the fee simple title to property.

end cap - 1. The endplate of a splice enclosure specifically arranged for the cable(s) entering and exiting the enclosure. 2. Closure at the end of a surface raceway or series of modular furniture units.

end node - A device attached to a network for originating or receiving information on that network.

end-of-line resistor (EOLR) - Resistor that permits active monitoring of a two-wire circuit by using low-level circuit current to detect a short or break.

endothermic - Absorbing heat energy.

endplate - See end cap.

end user - The ultimate consumer of a delivered good or service.

energy management system (EMS) - A computerized monitoring and control system used to manage and provide operational efficiency for electrical power, heating, ventilating, and air-conditioning, and lighting control systems.

energy per bit/spectral noise density (EbINO) - A signal to noise ratio applicable to digital communication systems; measured at the input to the receiver; used to predict receiver performance (e.g., bit error rate).

engineered judgment - Decision by a professional for a slight variance.

engine generator - A unit that uses a fuelpowered engine to drive a rotary generator to produce electrical power.

entrance bridge - A terminal strip that is an optional component in a network interface device and is provided for the connection of auxiliary disconnect outlet cable. (TIA)

entrance facility (EF) - 1. An entrance to a building for both public and private network service cables (including wireless) including the entrance point at the building wall and continuing to the entrance room or space. (TIA) 2. A facility that provides all necessary mechanical and electrical services for the entry of telecommunications cables into a building and that complies with all relevant regulations. (ISO)

entrance point (EP) - The point of emergence for telecommunications cabling through an exterior wall, a floor, or from a conduit. (TIA)

entrance room or space - A space in which the joining of inter or intrabuilding backbone facilities takes place. (TIA)

equalizer - An electronic device that compensates for the selective frequency losses of the cable that feeds into it.

equalizing conductor - Typically used for the equalization of different ground (earth) points of a building to keep them at the same potential (zero volt).

equal level far-end crosstalk (ELFEXT) - Crosstalk measured at the opposite end from which the disturbing signal is transmitted, normalized by the attenuation contribution of the cable or cabling.

equipment cable - A cable or cable assembly used to connect equipment to horizontal or backbone cabling. (TIA)

equipment distribution area (EDA) - Space allocated for end equipment including computer systems and telecommunications equipment. These locations shall not serve the purposes of an entrance room, main distribution area, or horizontal distribution area.

equipment grounding conductor - The conductor used to connect the' noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the system-grounded conductor, the grounding electrode conductor, or both at the service equipment.

equipment rack - Typically a vertical aluminum or steel support rack that holds equipment and cable terminations.

equipment room (ER) - An environmentally controlled centralized space for telecommunications equipment that usually houses a main or intermediate cross-connect. (TtA)

equivalent facilitation - Departures from particular technical and scoping requirements of this guideline by the use of other designs and technologies are permitted where the alternative designs and technologies used will provide equivalent or greater access to and usability of the facility.

error - Any unwanted change in the original contents of a transmission

error control - A process that verifies that a message is transferred successfully between devices.

errors and omissions (E80) - The failure to include or accurately define a requirement in a design document.

estimator - A person who evaluates a proposed scope of work for purposes of approximating labor and materials to plan or bid on proposed scope of work.

Ethernet ALAN - protocol using a logical bus structure and carrier sense multiple access with collision detection. Ethernet standards are formulated by the IEEE 802.3 committee and apply to Open Systems Interconnection Reference Model Layers 1 and 2.

Ethernet in the first mile (EFM) - The Institute of Electrical and Electronics Engineers 802.3ah project, Information Technology-Telecommunications and Information Exchange Between Systems-Local and Metropolitan Area Networks-Specific RequirementsPart 3: Carrier Sense Multiple Access with Collision Detection (CSMAlCD) Access Method and Physical Layer Specifications-Media Access Control Parameters, Physical Layers and Management Parameters for Subscriber Access Networks, to develop a standard Ethernet-based technology for linking subscribers to their telecommunications circuit providers.

European economic area (EEA) - An area composed of European Union, Iceland, Norway, and Liechtenstein.

European Radio Messaging System (ERMES) - A paging protocol defined by the European Telecommunications Standards Institute.

event - An occurrence at a controller (e.g., locking/unlocking a door, requesting to exit, forcing a door open) that generates a message stored in the controller.

event table - The results of some optical time domain reflectometers for optical fibers that list each event, its location, loss, and reflectance (if any).

existing facility evaluations - An investigation of an existing facility to help determine its suitability for adaptation to the owner's needs and goals, including functional, facility systems, structural, environmental, and accessibility evaluations. (CSI)

exothermic weld - A method of permanently bonding two metals together by a controlled chemical reaction releasing heat, resulting in a molecular bond. (TIA)

expansion joint - A joint between adjoining surfaces (e.g., concrete, conduit) arranged to permit expansion and contraction with changes in temperature.

exposed - Capable of being inadvertently touched or approached near than a safe distance by a person. It is applied to parts that are not suitably guarded, isolated, or insulated. (NEC)

exposed facilities - Any cable facilities subjected to such effects as lightning, power crosses, power induction, or differences in ground potential.

exposure monitor - A device worn by a cabling installer indicating the level of exposure to a hazardous substance.

extended service set (ESS) - A collection of wireless access points that are tied together by a wired backbone in a single collision domain, or by virtual LANs, to allow Layer 2 (Link layer) roaming.

extensible markup language (XML) - A specification developed by the W3C. XML is a pared-down version of standard generalized markup language, designed especially for Web documents. It allows designers to create their own customized tags, enabling the definition, transmission, vafidation, and interpretation of data between applications and between organizations. XML has been widely adopted for use in the integration of computiny systems with automation and control systems as the underlying language behind XML Web services.

extension arm - Metal or wood pole attachment for aerial cable to eliminate pull on an unguyed pole.

extranet - An interconnection of networks between organizations for the purpose of exchanging data. See also commerce server.