Glossary of Electrical Terms

Common Electrical, Wiring, and Battery Definitions



Back to Top

Alternating Current - An electric current that continually reverses its direction giving a definite plus and minus wave form at fixed intervals.

Ampere or Amp - A unit of measure for an electrical current. One amp (1 A) is the amount of current produced by an electromotive force of one volt acting through the resistance of one ohm.

Amp Hour or Ampere-Hour - A unit of measure of a battery's electrical storage capacity. Current multiplied by time in hours equals amp-hours. One amp hour (1 Ah) is equal to a current of one ampere flowing for one hour.

Amp Hour Capacity - The number of amp hours which can be delivered by a battery on a single discharge.

ASTM - Abbreviation for American Society for Testing and Materials.

AWG - American Wire Gauge - The standard system used for designating wire diameter. Also referred to as the Brown and Sharpe (B&S) wire gauge.

AWM - Appliance Wiring Material


Back to Top

Battery - An electrochemical device used to store energy. The term is usually applied to a group of two or more electric cells connected together electrically, but in common usage, the term battery is also applied to a single cell, such as a AA battery.

Battery Capacity - The electric output of a call or battery on a service test delivered before the cell reaches a specified final electrical condition and may be expressed in amper-hours, watt-hours, or similar units. The capacity in watt-hours is equal to the capacity in amp-hours multiplied by the battery voltage.

Boot - A protective covering over a portion of a cable or conductor that is in addition to its insulation or jacket.

Braid - A fibrous or metallic group of filaments interwoven in cylindrical form to form a covering over one or more wires.

Bunch Stranding - a method of stranding where a single conductor is formed from wires twisted together in the same direction, such that all strands have the same lay length, but no specific geometric arrangement.

Butt Joint - A splice or connection formed by placing the ends of two conductors together and joining them by welding, brazing or soldering.


Back to Top

Cable Core - A cable core is the portion of an insulated cable lying under the protective covering.

Cable Filler - The material used in multiple conductor cables to occupy the space formed by the assembly of components, thus forming a core of the desired shape.

Capacity - The measure of the amount of energy a battery can deliver in a single discharge. Battery capacity is normally listed as amp-hours (or milli amp-hours) or as watt-hours.

Cell - An electrochemical device, composed of positive and negative plates and electrolyte, which is capable of storing electrical energy. It is the basic "building block" of a battery.

Charge - The conversion of electric energy, provided in the form of a current, into chemical energy within the cell or battery.

Circular Mil - A unit of measure used in specifying cross-sectional areas of round conductors. One mil is a circle with area equal to 0.001 inch.

Coaxial Cable - A cable consisting of two conductors with a common axis separated by a dielectric.

Concentricity - In a wire or cable, the measurement of the location of the center of the conductor with respect to the geometric center of the circular insulation.

Conductivity - The capability of a material to carry an electrical charge

Conductor - A wire (or combination of wires not insulated from one another) suitable for carrying an electric current.

Conductor Stranding - Conductor Stranding is represented by two numbers separated by a slash. The first number indicates the number of strands of conducting material (typically copper) and the second number tells the diameter of each strand. For example, the conductor stranding of 12 gauge primary wire is 65/.0100, which means the conductor is composed of 65 individual strands of copper that are each .0100 inches in diameter.

Conduit - A tube or trough through which insulated wires and cables are run.

Copper (Cu) - With Atomic Number 29 and Atomic Weight 63.546, copper has a reddish color and takes a bright metallic luster. It is ductile, and and excellent conductor of electricity and heat (second only to sliver as an electrical conductor). Copper is commonly used through out the electrical industry.

Core - The center portion of a cable over which some other cable component, such as a jacket or shield is applied.

Crimp Termination - A wire termination that is applied by physical pressure of terminal to wire.

Cross Sectional Area - The area of the cut surface of an object cut at right angles to the length of the object.

Cross Sectional Area of a Conductor - The total of all the cross sectional areas of each of the individual wires composing the conductor. It is typically expressed in circular mils.

Crush Resistance Test - A test to determine the ability of a cable to resist damage from radial compression, such as might be encountered in service.


Back to Top

Decibel - Unit to express differences of power level. It is used to express signal power loss in cables.

Density - The weight per unit volume of a substance.

Dielectric Constant (K) - The ratio of the parallel capacitance (C) of a given configuration of electrodes with material as the dielectric, to the capacitance of the same electrode configuration with a vacuum as the dielectric.

Dielectric Strength - The voltage which an insulating material can withstand before breaking down, expressed as a voltage gradient (volts per mil).

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

Direct Current - Electrical current (constant or pulsating) whose electrons flow in one direction only. This is the type of electrical current supplied by a battery. One terminal is always positive and another is always negative.

Discharge - The conversion of the chemical energy of a battery into electric energy.

Drawing - In the manufacture of wire, pulling the metal through a die or series of dies for reduction of diameter to specified size.

Duct - an underground or overhead tube providing mechanical protection to electrical conductor which have been pulled through it.


Back to Top

Elastomer - A material that at room temperature returns rapidly to approximately its initial dimensions and shape after substantial deformation by a weak stress and release of the stress.

Elongation - The fractional increase in length of a material stressed in tension.

Embossing - Marker identification by means of thermal indentation leaving raised lettering on the sheath material of cable.

Energy - Output Capability - expressed as capacity times voltage, or watt-hours.

Energy Density - Ratio of cell energy to weight or volume (watt-hours per pound, or watt-hours per cubic inch).

Extrusion - The process of continuously forcing either a plastic or elastomer and a conductor or core through a die, thereby applying an insulation or jacket to the conductor or core.


Back to Top

Filler - Any material used in multiconductor cables to occupy interstices between insulated conductors or form a core into a desired shape (usually circular). Also, any substance, often inert, added to a plastic or elastomer to improve its properties.

Flexing Test - Any test to determine the ability of a cable to withstand repeated bending and twisting.

Flex Life - The number of twists or bends that a cable will withstand before failure.


Back to Top

Ground - A conducting connection, intentional or accidental, between an electric circuit or equipment and the earth or some conducting body serving in place of the earth.

Grounding conductor - A conductor, often colored green, used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.


Back to Top

Heat Endurance - The time of heat aging that a material can withstand before failing a specific electrical or physical test.

Heat Resistance - The ability of a substance to maintain it's physical and chemical identity and electrical integrity under specified temperature conditions.

Hertz (Hz) - SI unit of measuring cycles-per-second as an indication of frequency.


Back to Top

Insulation - Non-conducting materials separating the current-carrying parts of an electric machine from each other or from adjacent conducting material at a different potential.


Back to Top

Jacket - A material covering over a wire core or an assembly of components, usually an extruded plastic or elastomer.

Jumper - A short length of conductor used to make a connection between terminals, around a break in a circuit, or around an instrument.


Back to Top

Lay - The distance along a cable occupied by one complete helix of a strand or conductor. The direction of lay is the direction of the helix looking away from an observer. Also to arrange the wires or members of a conductor either by twisting them or by forming them into one or more layers helically applied.

Length of Lay - The axial length of one turn of the helix of wire or member.


Back to Top

Mil - Unit of measure equal to 1/1000 of an inch.

N Back to Top

Negative Terminal - The terminal of a battery from which electrons flow in the external circuit when the cell discharges. (See also Positive Terminal)


Back to Top

Ohm - The SI unit of measure of electrical resistance. A resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere.

Ohm's Law - Formula for calculating the amount of current flowing through a circuit. Ohm's Law states: In a given electrical circuit, the amount of current in ams (I) is equal to the pressure in volts (V) divided by the resistance, in ohms (R). Ohm's law can be shown by three different formulas:

Current Voltage Resistance
I = V/R V = I x R R = V / I

Open Circuit - Condition of a battery which is neither on charge nor on discharge (e.e. disconnected from a circuit).

Oxidation - A chemical reaction that results the release of electrons by an electrode's active material.

P Back to Top

Parallel Connection - The arrangement of cells in a battery made by connecting all positive terminals together and all negative terminals together. The voltage of the group remains the same as the voltage of the individual cell. The capacity is increased in proportion to the number of cells. (See Series Connection)

Plasticizer - A substance incorporated into a material to increase its workability or flexibility.

Plating - Any thin metallic coating applied over a metallic substratum.

Polychloroprene - A rubber-like compound used for jacketing where wire and cable will be subject to rough usage, moisture, oil, greases, solvents and chemicals.

Polymer - A material formed by the chemical combination of monomers having either the same or different chemical composition.

Polyvinyl Chloride (PVC) - A thermoplastic material composed of polymers of vinyl chloride, which may be rigid or elastomeric, depending on specific formulation.

Positive Terminal - The terminal of a battery toward which electrons flow through the external circuit when the cell discharges. (See Negative Terminal)


Back to Top


Quad - A structural unit employed in cables, consisting of four separately insulated conductors twisted together.

R Back to Top

Relay - A switch that is operated by an other electrical circuit.

Resistance - Property of a conductor that opposes the current flow produced by a given difference of potential. The ohm is the practical unit of resistance.


Back to Top


Secondary Insulation - Any extremely high resistance material which is placed over primary insulation to protect it from abrasion.

Semi-Conductor - A solid material characterized by comparatively high resistivity.

Series Connection - The arrangement of cells in a battery configured by connecting the positive terminals of each successive cell to the negative terminal of the next adjacent cell so that their voltages are cumulative. (See parallel Connection)

Sheath - The material, usually an extruded plastic or elastomer, applied outermost to a wire or cable, and usually referred to as the jacket.

Shield - Any barrier to the passage of interference - causing electrostatic or electromagnetic fields, formed by a conductive layer surrounding a cable core. It is usually fabricated from a metallic braid, foil or wire serving.

Shielding - The practice of confining the electrical field around a conductor to the primary insulation of the cable by putting a conducting layer over and/or under the insulation. (External shielding is a conducting layer on the outside of the insulation. Strand or internal shielding is a conducting layer over the conductor itself).

Short-Circuit - A condition that occurs when a short electrical path is unintentionally created. Batteries can supply hundreds of amps if short-circuited, potentially melting the terminals and creating fire.

Spark Test - A test designed to locate compromised insulation by application of an electrical potential across the material for a very short period of time while the wire is drawn through an electrode field.

Spiral Wrap - The helical wrap of a tape or thread over a core.

Splice - A joint used for connecting two lengths of conductor or cable with good mechanical strength as well as good conductivity.

Stabilizer - Any ingredient added to plastics to preserve their physical and chemical properties.

Strand - One of the wires of any stranded conductor.

Strand Lay - The distance of advance of one strand of a spirally stranded conductor in one turn, measured axially.

Stranded Conductor - A conductor composed of a group of wires, usually twisted, or of any combination of such groups of wire.

Switch - An electrical component that can break a circuit and interrupt or divert the current from one conductor to another.


Back to Top


Tear Strength - The force required to initiate or continue a rip in a jacket or other insulation under specified conditions.

Temperature Rating - The maximum temperature at which a given insulation or jacket may be safely maintained during continuous use, without incurring any thermally-induced deterioration.

Tensile Strength - The longitudinal stress required to break a specimen of prescribed dimension divided by the original cross-section area at the point of rupture (usually expressed in pounds per square inch).

Terminals - The parts of a battery to which the external electric circuit is connected.

Thermal Conductivity - Ability of material to conduct heat.

Thermal Rating - The maximum and/or minimum temperature at which a material will perform its function without undue degradation.

Tinned Wire - Copper wire that has been coated during manufacturing with a layer of tin to prevent corrosion or facilitate soldering.

Tolerance - A specified allowance for error from a standard or given dimension, weight or property.

Triplex - Three single conductors twisted together, usually three single conductor cables twisted without over-all covering. Do not use for three conductors laid parallel on a reel.


Back to Top


Volt - The unit of measurement of electomotive force, or difference of potential, required to make a current of one ampere flow through a resistance of one ohm.

Voltage Drop - The voltage developed between the terminals of a circuit component by the flow of current through the resistance or impedance of that part.

Voltage Rating - The maximum voltage at which a given cable or insulated conductor may be safely maintained during continuous use in a normal manner. It is also called working voltage.


Back to Top


Watt - A measurement of total power. It is amperes multiplied by volts.

Wire Gauge - A standard system for designating wire sizes. AWG is one example of a standards system for wire.