Innovations in Communications™ Since 1955

LEE DAN® COMMUNICATIONS, INC.
155 Adams Avenue, Hauppauge, New York, 11788-3699 USA
Phone: 800-231-1414 or 631-231-1414 Fax: 631-231-1498 E-Mail: info@leedan.com
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Glossary of Terms
All Call
Allows simultaneous ‘talk’ to all intercom speakers. Most commonly used with Lee Dan’s TEK-COM common talk intercom system.
Alternating Current (AC)
Differs from direct current (DC) in only one very important point. It typically starts at zero, gradually increases to a maximum, then gradually decreases to zero. This change is then repeated in the opposite direction. Alternating current changes direction 60 times per second.
American Wire Gauge (“AWG”)
A standard system for designating wire diameter. Most intercoms use 22 AWG (read “22 gauge”) wire, although the transformer and door strike wiring is usually 18 AWG. The larger the number, the smaller the wire diameter. Hence 22 AWG wire is thinner than 18 AWG.
Ampere
The unit of current. One ampere is the current flowing through one ohm of resistance at one volt potential. Analogous to gallons of water flow past a given point.
Audio Frequency
The range of frequencies audible to the human ear. Usually 20-20,000 Hz.
Buried Cable
A cable installed directly in the earth without use of underground conduit. Also called “direct burial cable.”
Cabling
The twisting together of two or more insulated conductors to form a cable.
Call Tone
Electronic tone signal which sounds when a remote/sub station calls a master station.
Capacitance
Ratio of the electrostatic charge on a conductor to the potential difference between the conductors required to maintain that charge.
Circuit
Path through which electrical energy flows to and from the source to the devices being operated.
Coaxial Cable
A cable consisting of two cylindrical conductors with a common axis, separated by a dielectric. Generally used to carry video signals. See Lee Dan model RG-59U.
Color Code
A system for circuit identification through use of solid colors and contrasting tracers or striped conductors.
Common Wire(s)
Common wires may be looped/connected from station to station (occasionally distance limitations may prevail).
Conductance
The ability of a conductor to carry an electric charge. The ratio of the current flow to the potential difference causing the flow. The reciprocal of resistance.
Conductivity
The capacity of a material to carry electrical current—usually expressed as a percentage of copper conductivity (copper being 100%).
Conductor
An uninsulated wire suitable for carrying electrical current.
Conduit
A tube, pipe or trough in which insulated wire and cables are run.
Continuity Check
A test to determine whether electrical current flows continuously throughout the length of a single wire or individual wires in a cable.
Coverage
The percent of completeness with which a metal braid covers the underlying surface.
Crosstalk
Signal interference between nearby conductors caused by pickup of stray energy.
C.S.A.
Abbreviation of Canadian Standards Association, a nonprofit, independent organization which operates a listing service for electrical and electronic materials and equipment. The Canadian counterpart of the Underwriter’s Laboratories.
Current Carrying Capacity
The maximum current an insulated conductor can safely carry without exceeding its insulation and jacket temperature limitations.
Desk Mount
A method to mount a station on a desktop, usually with a sloping face, and generally using Lee Dan model IH-400A.
Direct Current (“DC”)
Term used to describe the flow of electrical current in one direction only, uniform and continuous.
Door Station
A remote (sub) station located at a door or gate. Usually weather resistant, available with or without a call button for tone signalling. Communication is hands-free at the door, and controlled by the indoor master.
Door Strike
(also Door Opener)
An electro mechanical device used to unlock a door from a remote location. Most popular is Lee Dan model DO-001.
Drain Wire
In a cable, the uninsulated wire laid over the component or components and used as a ground connection.
Fail Safe 
In a power down state, the device is unlocked or unlatched.
Fail Secure
In a power down state, the device is locked or latched.
Flush Mount
A mounting method requiring a cutout be made into the finished wall or other surface. Flush mounted equipment will be recessed into the wall so the mounted object protrudes little from the face of the wall (see ‘recessed’).
Gauge
Term used to denote the physical size of wire or metal.
Ground
A conducting connection between an electrical circuit and the earth or other large conducting body to serve as an earth thus making a complete electrical circuit. The purpose is to minimize danger from electrical shock and prevent lightning 
Hands-Free Reply
Ability to reply to an incoming call from a master station, without touching your intercom.
High Voltage
Generally, a wire or cable with an operating voltage of over 600 volts.
Hook-Up Wire
A wire used for low current, low voltage (under 1000 volts) applications within enclosed electronic equipment.
Horizontal Mailbox
A multi compartment mailbox with deep ‘horizontal’ doors/compartments. Horizontal mailboxes generally require very deep walls of 15" or more. Horizontals are more expensive than ‘vertical’ mailboxes, but generally allow more boxes to be installed in limited wall (width) space.
Housing
A mounting device used to install a station or panel. There are three popular kinds; flush (recessed), surface, or desk mount.
Impedance
The total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency. It is a combination of resistance R and reactance X, measured in ohms.
Insulation
A material having high resistance to the flow of electric current. Often called a dielectric in radio frequency cable.
Jacket
An outer nonmetallic protective covering applied over an insulated wire or cable.
Key Keeper
Used in buildings with mailboxes located behind a locked entry door. This lock box is designed to hold the key to an apartment or office building, for use by the local postal carrier. Always sold without a lock. The (postal) lock is provided and installed by the local post office.
L.E.D. Annunciation
L.E.D.’s (light emitting diodes) used on a master, under each selector button used to indicate which remote is calling a master. Master operator then presses indicated selector button to control conversation.
Master Station
An intercom station which can both initiate and control both elements (Talk, Listen) of a conversation.
Mortise
A notch or hole cut in a piece of wood or metal to receive a projecting part shaped to fit.
Multiconductor
More than one conductor within a single cable complex.
Ohm
A unit of electrical resistance. Often written or indicated by the Greek letter Omega.
Pedestal Mailbox
A multi compartment mailbox mounted on a steel or other secure pedestal for outdoor use. Typically in condominium communities. Deep doors/compartments are similar to ‘horizontal’ style mailboxes. 
Postal Approved
Any mailbox approved by the Postmaster General of The US Postal Service. Manufacturers must make detailed submittals to Washington and conform to specific Size, Material, and Safety specifications.
Privacy
An intercom with privacy activated can receive calls (listen), but the response is blocked for privacy. 
Recessed
A mounting method requiring a cutout be made into the finished wall or other surface. Recessed equipment will be recessed into the wall so the mounted object protrudes little from the face of the wall (see ‘flush’).
Rectifier
An electrical unit designed to convert alternating current to direct current. 
Remote Station
An intercom station which can respond to a call from a master station. Remote stations may be equipped with a call button for tone signalling only to a master station. Also commonly referred to as ‘sub station’. 
Resistance
A measure of the difficulty in moving electrical current through a medium when voltage is applied. It is measured in ohms.
Riser
A cable run used to connect a group of intercom stations. Most commonly referred to in apartment intercom systems where ‘vertical’ risers are most common.
Selective Calling
Ability to call a specific intercom station by pressing that station’s selector button. Communication at the calling master is push to talk, release to listen. The called station may communicate hands-free.
Selective Wire(s)
Selective wires are used to uniquely identify a specific intercom station. 
Shield
In cables, a metallic layer placed around a conductor or group of conductors to prevent electrostatic or electromagnetic interference between the enclosed wires and external fields.
Sub Master
Hybrid intercom station which, like any remote (sub) station can receive a call from a master, but may additionally be able to make an All Call, and/or answer a call from a door station. Most common in Lee Dan’s TEK-COM common talk intercom system. 
Sub Station
An intercom station which can respond to a call from a master station. Sub stations may be equipped with a call button for tone signalling only to a master station. Also commonly referred to as ‘remote station’. 
Surface Mount
A mounting method utilizing the finished surface of a wall as the anchor point. Surface mounted stations or panels will protrude their full depth from the face of the wall.
Switch
A device placed in an electrical circuit in order to make or break the flow of electrical current.
Transformer
A device for transferring energy in an alternating current system from one circuit to another. Thus energy at high voltage may be transformed to energy at low voltage and vice-versa. Most intercom applications operate at low voltage, and thus require a “step down” transformer to reduce voltage to system specifications (most typically 16 or 24 volts).
Twisted Pair Cable
Cable with individually twisted pairs of wires within a single jacket.
UHF
Abbreviation for ultra high frequency, 300 to 3,000 Mhz.
U.L. 
Abbreviation of Underwriter’s Laboratories, a nonprofit, independent organization which operates a listing service for electrical and electronic materials and equipment.
USPS
U.S. Postal Service
Vertical Mailbox
A multi compartment mailbox with tall ‘vertical’ doors/compartments. “Verticals” are less expensive than ‘horizontal’ mailboxes, but generally require more wall (width) space, and are not usually suited for larger installations (100+ compartments).
VHF
Abbreviation for very high frequency, 30 to 300 Mhz.
Voltage
The term most often used in place of electromotive force, potential difference, or voltage drop to designate the electric pressure that exists between two points and is capable of producing a current when a closed circuit is connected between two points. Analogous to the pressure in the water pipes of your home.
Voltage Rating The highest voltage that may be continuously applied to a wire in conformance with standards or specifications
This page was last updated May 17, 2016

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