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The Book of Terms

The Book of TermsThe WJI Book of Wire & Cable Terms: an interactive experience of learning and sharing
This book, written by industry volunteers and containing more than 5,000 entries, is an asset for newcomers to wire and cable.

At the same time, it also represents an opportunity for industry veterans to give back by either updating or adding to the more than 5,000 entries. This is an honor system process. Entries/updates must be non-commercial, and any deemed not to be so will be removed. Share your expertise as part of this legacy project to help those who will follow. Purchase a printed copy here.


All   0-9   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Designation for varnished cambric insulation with fibrous covering.


Designation for voltage to frequency.


Designation for voltamperes, the apparent power in an AC circuit.

Vacuum Annealing

Vacuum is best characterized as a lack of atmosphere (e.g., air, oxygen or other gases). Hence when metals or alloys are heated to high temperatures in a vacuum furnace, there is essentially no oxygen present to oxidize and discolor the surface of the material. Note: vacuum annealing is not conducive to strand annealing (e.g., uncoiling, heating and recoiling).

Vacuum Casting

Technique of casting where there is a vacuum suction at the exit end of the mold.

Vacuum Fusion

Testing procedure to determine oxygen content in a copper sample.

Vacuum Melting

Melting in a vacuum to prevent contamination from air, as well as to remove gases already dissolved in the metal; the solidification may also be carried out in a vacuum or at low pressure. Also known as vacuum refining.

Vacuum Pyrolysis

A method of cleaning hardware that is used in extruding jacketing material.

Vacuum Refining

See Vacuum Melting.

Vacuum Switch

1) A switch with contacts in an evacuated enclosure. 2) A switch that senses a vacuum level to actuate contacts.


Any void between the insulated conductors of a cable or between a cable core and its covering. See also Interstice.

Valve Spring Wire

Chrome-silicon or chrome-silicon-vanadium alloyed steel wire that has 0.50 to 0.70 percent carbon. Valve springs are typically made by cold coiling of wire that has been subjected to shaving, cold drawing, hardening and tempering. Fatigue strength and sag resistance are two major factors. Tensile strength has increased over the years from 1700 MPa (247 ksi) to as much as 2150 MPa (312 ksi). Nitriding and special designed shot peening can further enhance the fatigue properties. Valve springs in applications working at elevated temperature or corrosive atmosphere are made of a precipitation hardened stainless steel grade 177 PH (AISI 631).


Element, chemical symbol V. A gray metal primarily used as an alloying agent for iron and steel and as a strengthener for titanium-based alloys. It imparts an even distribution of carbon, but requires the inclusion of other elements to develop this property to its fullest extent. Vanadium increases the toughness of medium and low carbon steels by its solid solution with the ferrite, and prevents brittleness in high carbon qualities. Frequently used in conjunction with chromium and manganese as an alloying agent, chrome-vanadium steels being used for springs, tools, etc. It is also a catalyst in sulfuric acid production.

Vapor Blasting

A process by which the surface of a component is modified by the action of a stream of liquid carrying solid particles of abrasive energized by com­pressed air.


So enclosed that vapor will not enter.


Designation for volt-amperes reactive, the mathematical imaginary power component in an AC circuit.

Variable Speed Drive

A motor or drive train that has the ability to vary its output speed through a continuous range.

Varnished Cloth

Tape wraps of varnished cambric for insulation of wire and cable offer properties that lie between those of rubber and impregnated paper. This applies to dielectric strength, flexibility, resistance to moisture and heat and handling cable connections and terminations. It provides a greater measure of moisture resistance than paper. In dry locations, it may be used without a lead sheath. It can be used for low and moderate voltage cables.


Designation for: 1) varnished cambric-insulated (cables) 2) vertical cast (wire bars).


Designation for varnished cambric insulation, cotton braid, flame retarding, moisture resisting finish.

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