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Electrical Engineering Terms E

Eddy Currents.

Circulating currents induced in conductive materials by any type of varying electromagnetic fields.

Effective Ground-Fault Current Path.

An intentionally constructed, low-impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source to facilitate the operation of the overcurrent protective device or ground-fault detectors on high-impedance grounded systems.


(1) A conductor through which current transfers to another material, or (2) a conducting material through which current either enters or leaves a device, utilization equipment, a circuit, or a power distribution system.


A general term used to the described material, fittings, devices, appliances, luminaires (fixtures), apparatus, and the like used as a part of, or in connection with an electrical installation.

Equipment Bonding Jumper.

The connection between two or more portions of the equipment-grounding conductor.

Equipment Ground.

The grounding connection, normally with a non-circuit conductor, of the non-current-carrying metal parts of a wiring installation, or of the electrical distribution or utilization equipment supplied.

Equipment-Grounding Conductor.

(1) A bare, green-covered, or green insulated conductor run with the supply-circuit conductors to connect the non-current-carrying metal parts of equipment, raceways, and other enclosures to the electrical-power distribution system neutral or other grounded conductor and/or the grounding-electrode conductor either at the service equipment, or at the source of a separately derived system, or; (2) a conductive path(s) installed to connect the normally non–current-carrying metal parts of electrical distribution/utilization equipment together and to the electrical-power distribution system grounded conductor or to the grounding electrode conductor, or both.

Equipment-Grounding System.

Interconnection of all the noncurrent-carrying metal parts of a building or other structure or premise electrical-power distribution system with the grounded service neutral conductor at the point where the service neutral conductor is referenced to earth ground.

Efficiency. As used with electric motors, the NEMA full-load efficiency basically lists as a percentage the amount of electrical energy supplied to the electric motor that is converted into kinetic energy. The remaining power is a loss that is converted mostly into heat.

Electromotive Force (EMF). Normally abbreviated to the acronym EMF, this term can be described in two different ways: (1) the electrical pressure or force that pushes electrons through a circuit conductor; (2) the force that causes electrical current flow when there is a difference of potential between two points. The most common definition of circuit or source voltage, an electromotive force is not the same as potential difference, which is the voltage developed across a circuit element as a result of the current in the element.

Explosion proof (EXP). Normally abbreviated to the acronym EXP, this term describes motor enclosures designed to be used in areas that have hazardous atmospheres; the end bells and the cylindrical motor housing are totally enclosed and non-vented.

Electromagnetic (Magnetic) Field. Comprised of lines of force, this field is the region surrounding a magnet through which magnetic forces act. The magnetic field is most intense near the poles of the magnet and as the distance from the magnet is increased, these lines of force become weaker and weaker (because of the surrounding air’s high reluctance), until they are finally nonexistent.

Excitation Current. The primary current that supports the continual reversal of the magnetic-pole polarities (core losses, dissipated as heat) in a transformer. This current contributes to the energy expended due to eddy-current and hysteresis losses. The expended electrical energy of this current is referred to as iron core losses in the transformer, which are normally dissipated as heat (I2R losses).

Engineering Notation.

A classification for representing large and small numbers by using a 1, 2, or 3 digit number times a power of ten that is a multiple of 3.


A symbol written above and to the right of a mathematical expression to indicate the operation of raising to a power.


About Ahmed Faizan

Mr. Ahmed Faizan Sheikh, M.Sc. (USA), Research Fellow (USA), a member of IEEE & CIGRE, is a Fulbright Alumnus and earned his Master’s Degree in Electrical and Power Engineering from Kansas State University, USA.

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