H

Shielded power cable. Multi-conductor cables have paper or varnished cambric insulation applied directly over individual conductors. Spiralled metallic shielding tape over insulation with overall protective covering.

Hard Drawn Copper Wire

Copper wire that has been drawn to size and not annealed.

Harness

A term used to describe a group of conductors laid parallel or twisted by hand, usually with many breakouts, laced together or pulled into a rubber or plastic sheath, used to interconnect electrical circuits.

Hash Mark Stripe

A non-continuous, helical stripe applied to a conductor for circuit indentification.

HC

Two or more conductor heater cord, asbestos and rubber insulation with cotton braid over each conductor. Twisted, no overall covering.

HDP

High density polyethylene

Headroom

The overhead of margin, expressed in decibels, by which a communications system exceeds minimum requirements.

Heat Distortion

Distortion or flow or a material or configuration due to the application of heat.

Heat Seal

In cabling, a method of sealing a tape wrap jacket by means of thermal fusion.

Heat Shock

A test to determine stability of a material by sudden exposure to a high temperature for a short period of time.

Heat Sink

A metal plate used for absorbing or removing heat for the switching device in a dimmer or fan speed control

Heat Sink Dimmer/Fan Speed Control

Any dimmer or fan speed control that mounts onto a NEMA standard switch box and onto the surface of the wall itself. Heat sink dimmers and fan controls will not accept a traditional wall plate and usually are supplied with their own unique cover.

Helical Stripe

A continuous, colored, spiral stripe applied over the outer perimeter of an insulated conductor for circuit indentification purposes.

Helix

A spiral winding.

Henry

An electrical unit denoting the inductance of a circuit in which a current varying at the rate of one ampere per second produces an electromotive force of one volt.

High Inertia Load

These are loads that have a relatively high flywheel effect. Large fans, blowers, punch presses, centrifuges, commercial washing machines and other types of similar loads can be classified as high inertia loads.

High Speed Fuses

Fuses with no intentional time-delay in the overload range and designed to open as quickly as possible in the short-circuit range. These fuses are often used to protect solid-state devices.

High Voltage Fuses

Fuses rated 34,500 volts and above.

HMP

High molecular weight polyethylene.

Home Run

Also known as star topology, a cabling system where indiviual calbes are run directly from the telecomunnications closet to each information outlet.

Hook-up Wire

A wire used for low current, low voltage (under 1000V) applications internally within enclosed electronic equipment.

Horizontal Cabling

The portion of the wiring system extending from the workstation to the horizontal cross-connect in the telecommunications closet.

Horizontal Cross-Connect

The cross-connection between horizontal and other cabling, such as backbone cabling.

Horizontal Length

The cable distance from the workstation to the telecommunications closet cross-connect, a maximum of 295 ft. (100 meters).

Horizontal Stripe

A colored stripe running horizontally with the axis of a conductor, sometime called a longitudinal stripe, used as a means of circuit identification.

Horsepower Rated

A device having a marked horsepower rating intended for control of motor loads.

Hospital Grade

A device constructed to meet performance requirements of high abuse areas found in hospital locations, tested to "Hospital Grade" requirements of Underwriters Laboratories Standard UL498

Hospital Only

A connector which is listed by Underwriters Laboratories INC for use in health care facilities.

Hot Dip

A term denoting the covering of a surface to be coated into a molten bath of the coating material.

HPD

Rubber and asbestos-insulated heater cord. No braid on individual conductors but with braid overall. Also made with neoprene insulation and no asbestos or PVC/NBR.

HPN

Two-conductor, neoprene-insulated heater cord. Parallel construction. For use in damp locations.

HS

Rubber and asbestos-insulated heater cord. Cotton serve and rubber-jacketed overall. For use in damp locations #14 or #12 conductors. Also made with neoprene insulated inners and asbestos.

HSJ

Same as type HS but with #18 or #16 conductors and differing thickness of jacket.

HSJO

Same as type HSJ but with neoprene jacket.

HSO

Neoprene jacketed heater cord.

Hub

Equipment which serves as a centralized connection point for a network or a portion of network. Hubs contain multiplexing, switching, and bridging functions and are not considered part of the cabling infrastructure.

HV

High voltage

HW

Radio hookup wire with polyvinyl insulation. With or without nylon jacket, braid or shield, 2500V.

Hybrid Cable

A multi-conductor cable containing two or more types of component.

Hygroscopic

Readily absorbing and retaining moisture.

Hypalon®

Dupont trandmark for chlorosulfonated polyethylene (CSPE) synthetic rubber.

Hysteresis

The error defined by the maximum deviation of measured output from a best fit straight line during any one calibration cycle.