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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: 1) Fahrenheit, one of the two commonly used temperature scales, Celsius being the other (see listing for each). 2) Flat band metallic armor.

Factor of Assurance

The ratio of the voltage at which wire or cable insulation is tested to that at which it is used.

Factorial Experiment

Having more than one factor as a controlled variable in one experiment. This produces much data, but the results are complex to analyze.

Factory Representative

An individual or a company using its own sales force to act as a manufacturer’s agent.


A scale for measuring temperature. Water freezes at 0°C (32°F) and boils at 100°C (212°F). It often is cross-referenced with the scale for Celsius (see entry).


An item’s inability to perform or to continue to perform its required function.

Falex Test

A loosely used term to indicate a test procedure for either: 1) determining the resistance of a material to scratching and abrasion; or 2) determining the lubrication characteristics of a fluid. The title evolved from the fact that Falex Corporation was one of the first manufacturers of this type of equipment.

Fancy Chain

A variation of both twisted wire and stamped links, in the form of chain.

Far-End Crosstalk



A unit of capacitance. It is usually ex­pressed in microfarads (mF = one millionth of a farad) or picofarads (pF = one millionth of a microfarad). A one-farad capacitor is one in which a one coulomb charge produces a one volt potential difference between the plates.

Faraday Shield

A network of parallel wires connected to a common conductor at one end to provide electrostatic shielding without affecting electromagnetic waves. The common conductor is usually grounded.


A generic term used to describe bolts, screws, nuts, rivets, clips, etc.

Fat Emulsions

A general term in blending metal working coolants, where “fat” can be derived from vegetables, animals and even fish as an ingredient along with soap and other chemicals in water to provide lubrication and cleaning of the products and equipment during various wet metalworking operations. Synthetics esters have replaced or augmented the usage of fat.


The phenomenon leading to fracture of a material that is under repeated or fluctuating stresses having a maximum value less than the ultimate tensile strength of the material. Fatigue failure generally occurs at loads which applied statically would produce little perceptible effect. Fatigue fractures are progressive, beginning as minute cracks that grow under the action of the fluctuating stress. There is no obvious warning. A crack can form without appreciable surface deformation, making it difficult to detect. Fractures often start from small nicks or scratches or fillets that cause a localized concentration of stress. Failure can be influenced by a number of factors including size, shape and design of the component, condition of the surface or operating environment.

Fatigue Ductility

The ability of a material to deform plastically before fracturing, determined from a constant-strain amplitude, low-cycle fatigue test. Usually expressed in percent in direct analogy with elongation and reduction in area ductility measures.

Fatigue Failure

Failure that occurs when an item completely fractures into two parts or has softened or been otherwise significantly reduced in stiffness by thermal heating or cracking due to fatigue.

Fatigue Life

1) The number of cycles of a specified character that a given item sustains before failure of a specified nature occurs. 2) The number of cycles of deformation required to bring about failure of a test specimen under a given set of oscillating conditions (stresses or strains).

Fatigue Limit

The maximum stress that presumably leads to fatigue fracture in a specified number of stress cycles. The value of the maximum stress and the stress ratio also should be stated.

Fatigue Striation

Parallel lines frequently observed in electron microscope fractographs or fatigue fracture surfaces. The lines are transverse to the direction of local crack propagation; the distance between successive lines represents the advance of the crack front during the one cycle of stress variation.

Fatigue Wear

Wear of a solid surface caused by fracture arising from material fatigue.

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