Term

Definition

UD

Underground distribution.

UF

Thermoplastic underground feeder and branch circuit cable.

UL

Underwriters Laboratory. Standards and test that wire must meet in order to receive UL approval.

UL/CSA Class Fuses

General purpose fuses meeting one of the industry standards called "classes." Fuse classifications H, J, K, L, R, CC, G and T. Qualifying fuses are typically tested and certified by UL or CSA to tri-national Fuse Standard 248.

Ultra-Violet Degradation

The degradation caused by long time exposure of a material to sunlight or other ultraviolet rays containing radiation.

Undervoltage relay

A relay that operates when the voltage applied to the relay is equal to or less than its setting.

Unidirectional Concentric Stranding

A unidirectional stranding where each successive layer has a different lay length thereby retaining a circular form without migration strands from one layer to another.

Unidirectional Stranding

A term denoting, that in a stranded conductor all layers have the same directional lay.

Unilay Stranding

A bunched construction having 19, 27, 37, or any number of strands which might be found in a concentric stranding.

Unipolor or Acyclic Machine

A direct current machine in which the voltage generated in the active conductors maintains the same direction with respect to those conductors.

URC

Weatherproof wire.

URD

Underground residential distribution.

USE

Underground service entrance cable, rubber-insulated, neoprene or XLP jacketed.

USOC (Uniform Service Order Code)

Bell system term to denote varying pin configurations on registered jacks (RJs).

UTP (Unshielded Twisted Pair)

Twisted-pair copper cable without metallic braid shielding - capable of high-speed voice and data transmission. The most common cabling used in the U.S. structured wiring.

V

Varhished-cambric insulation, with fibrous covering.

Variable Speed Motor

A motor with a positively damped speed-torque characteristic which lends itself to controlled speed applications.

Varistor

variable resistor

Varying-Speed Motor

A Motor whose speed varies with the load, ordinarily decreasing when the load increases.

VCB

Varnished-cambric insulation, cotton braid, flame-retarding, moisture-resisting finish.

VCL

Varnished-cambric insulation, lead-covered cable. Ends must be hermetically sealed.

VD

Indicates a twin wire having two type V conductors laid parallel under an outer fibrous covering.

Velocity of Propagation

In cable measurements, a function of dielectric constant. The transmission speed of an electrical signal down a length of cable compared to speed in free space - expressed as a percentage of speed in free space.

Ventilated

Provided with a means to permit circulation of air sufficient to remove an excess of heat, fumes or vapors.

Vertical-break switch

A switch in which the travel of the blade is in a plane perpendicular to the plane of the mounting base.

VG

Varnished-glass tape over a flexible copper conductor. Varnished-glass or nylon braid. 600V or 3000V, 130°C

VIP

Vulcanized interlinked polyethylene.

Viscous

Thick - Resistant to flow. Applied to a liquid.

VM

Indicates a cable having two or more type V conductors twisted together under an outer fibrous covering.

Volt

A unit of electromotive force.

Volt Amperes or Apparent Power

The product of the voltage across circuit and the current in the circuit.

Voltage

A difference of potential measured in volts. The electric pressure available to cause a flow of electrons.

Voltage Drop

A term expressing the amount of voltage loss from original input in a conductor of given size and length.

Voltage Rating

The maximum open circuit voltage in which a fuse can be used, yet safely interrupt an over current. Exceeding the voltage rating of a fuse impairs its ability to clear and overload or short circuit safely.

Voltage Ratio

The voltage ratio of a transformer is the ratio of the r.m.s. primary terminal voltage to the r.m.s. secondary current, under specified conditions of load.

Voltage relay

One which functions at a predetermined value of voltage. A voltage relay may be either an over-voltage relay or an under-voltage relay.

Voltage Standing Wave Ratio

>The ratio of the maximum effective voltage to the minimum effective voltage measured along the length of a mismatched radio frequency transmission line.

Voltage Stress

The stress found within a material when subjected to an electrical charge.

Voltmeter

An instrument of high resistance for measuring differences of pressures in volts.

Volume Resistivity

The volume resistance between two electrodes of unit area and unit distance apart that are in contact with, or imbedded in, a specimen, is the ratio of the direct voltage applied to the electrodes to that portion of the current between them that is distributed through the volume of the specimen. Usually expressed in ohms/centimeter.

VW-1

Vertical wire flame test, formerly designated as FR1.

W

Heavy duty portable power cable, one to six conductors. 600V, without grounds.

W/G

With ground

W/O/G

Without ground

Wall Plate

A plate designed to enclose a device box with or without a divice installed in the box.

Wall socket

Any socket placed in a wall for the purpose of admitting a plug for making electrical connection with supply wires.

Wall Thickness

A term expressing the thickness of a layer of applied insulation or jacket.

Water Absorption Test

A method to determine the water absorbed through an insulating material after a given water immersion period.

Waterblocked Cable

A cable specially constructed with no internal voids in order to allow no longitudinal water passage under a given pressure.

Watt

A unit of electrical power; the power of one ampere of current pushed by one volt of electromotive force.

Wave Length

The distance, measured in the direction of propogation, of a repetitive electrical pulse or waveform between two successive points that are characterized by the same phase vibration.

Wave-Form or Wave-Shape

The shape of the curve obtained when the instantaneous values of an alternating current are plotted against time in rectangular coordinates. The distance along the time axis corresponding to one complete cycle of values is usually taken as 2(pi) radian, or 360 electrical degrees.

Weatherproof

A device constructed or protected such that exposure to weather will not interfere with successful operation. (N.E.C.)

Welder Protector

A fuse with special characteristics to meet heavy inrush current demands of an electric welder and protect the welder on short circuits.

Wet Location; Cover Open

A cover, UL listed in accordance with specific test standards for use in wet and damp locations with the cover opened (plug cap inserted) or closed.

Wet Location; Only with Cover Closed

A cover UL listed in accordance with specific test standards for use in damp locations with the cover closed, or wet locations only when cover is closed.

Wetting

The ability of a material to absorb moisture.

Wicking

The longitudinal flow of a liquid in a wire or cable construction due to capillary action.

Wire

(1) A single piece of slender, flexible metal ranging in approximate size from a piece that is difficult to bend by hand to a fine thread. (2) Several wires as in (1) twisted together. (3) Wires as in (1) or (2) insulated.

Wire Mesh Grip

(Flexcor) Woven wire mesh holding devices used to support, pull, or relieve strain exerted upon cables, conduit, tubing and various other items.

Wiring Closet

Termination point for Customer premises wiring offering access to service personnel.

Withstand Rating

The maximum current that an unprotected electrical component can sustain for a specified period of time without the occurence of extensive damage.

Work Area Outlet

A connecting device in the work area where horizontal cable terminates and work area equipment can be connected. Also called information outlet and telecommunications outlet.

Workstation

The location where telecommunications cabling is connected to work area equipment (PCs and peripherals) by means of a telecommunications outlet. Also called work area outlet and information outlet.

WP

Weatherproof construction, two or three impregnated cotton braids. 80°C

W-Type

Same as Y type except having three cord connectors arranged in the form of the letter W.

X

Two FX wires twisted together, color coded. 125V, 60°C.

XHHW

High temperature (90°C) chemically cross-linked polyethylene jacketed small diamter building wire.

XLP

Cross-linked polyethylene.

XT

Two FXT wires twisted together, color coded. 125V, 60°C

Yield Strength

The minimum stress at which a material will start to physically deform without further increase in load.

Y-Type

An adapter in the form of a letter Y having two cord connectors on one end and a male plug on the other end.

Z

Symbol for impedance

Zero (Balance)

The output of the transducer when zero pressure is applied.