| 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 |
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