Frequently Used Terms

Adjustable hold open [AHO]
A door closer option which can be adjusted to hold a door open at different positions

Alternating current [AC]
An electric current that reverses (alternates) it's polarity regularly and continually. Also known as AC current.

Americans with Disabilities Act [ADA]
A US federal law dealing with minimum standards of building accessibility, as well as other issues concerning individuals with disabilities

Ampere [AMP]
The unit of measurement for the rate of current flow.

Annunciator
A signalling device which can be either audible or visual

Audit trail
A running history of events which occur in an access control system

Authority having jurisdiction [AHJ]
The person, usually within a municipality, charged with the application and interpretation of local life safety codes

Backcheck
A hydraulic function built into a door closer which prevents a door from swinging open uncontrolled

Backset
The distance of measurement between the center of a cross-bore and the bolt edge of a door or drawer

Barrier free [BF]
Having to do with the absence of restrictions to access by the handicapped

Battery backup
A backup source of power for an access control system.

Center Hung
A door hung on pivots, with the pivot point within the dimension of the door

Common [C]
A terminal on a form-C relay or a single pole double throw switch which is used to complete a circuit.

Continuous duty
The duty rating of an electrical device. Continuous duty rated devices are designed to be powered continually.

Current
The flow of electrons measured in amperes (amps)

Current draw
The amount of current (amps) consumed by a device in an electrical circuit.

Delayed action
A function of a door closer which delays the closing of a door to allow for passage by a wheelchair

Delayed egress
A means of egress controlled (delayed) to prevent pilferage. Delayed egress must meet the requirements of NFPA101.

Direct current [DC]
An electric current that travels in only one direction and typically has a negative and positive polarity.

Double acting (door)
A door which swings in both directions

Double pole - double throw [DPDT]
A type of switch or relay (form-C) where two circuits are activated simultaneously.

Dry contact
Terminals on a relay which do not supply power but function to open or close a circuit

Exit door
A door typically used as a means of egress in an emergency.

Face
The exposed part of a frame parallel to the surface of the wall

Fail safe [FS]
a feature of a security device designed to release, for safety purposes, during a power loss. (also known as fail-unlocked or reverse action).

Fail secure [FSE, NFS]
A type of electrically operated lock which in an unpowered state is locked. (also known as fail-locked or non fail safe)

Finish
The finished color of a lock or other door hardware.

Fire door
A door constructed to provide a specific degree of fire protection. It is typically rated for a period of time as resistant to penetration by fire.

Form-C
A type of switch mechanism which includes three terminals: common, normally open and normally closed.

Ground
A conducting connection between an electric circuit and the earth

Hand
The orientation of a locking device which matches the bevel or direction of swing of a door. Designations for handing are: RH, LH, RHR, LHR. On pairs of doors, the suffix -A may indicate that a leaf is the active leaf in the pair ie: RHR-A

Hold open
A door closer option which allows a door to be held open

Inrush current
The measurement of amperage that an electrical device needs when power is first applied

Intermittent duty
The duty rating of an electrical device which is not designed to be continuously powered.

Labeled fire door (see fire door)

Load (see current draw)

Maintained contact switch
A switch designed to continually pass current or close a circuit in its normal condition

Momentary contact switch
A switch designed to pass current or close a circuit on demand

Monitoring
A method of indicating the operational status or security condition of a locking device or a door.

NFPA 101
National Fire Protection Association life safety code

Normally open [NO]
The normal condition of a switch or relay contact in which a circuit is open

Normally closed [NC]
The normal condition of a switch or relay contact in which a circuit is closed

No special knowlege
A descriptive term which relates to the NFPA101 life safety code

Non-fail safe (see fail secure)

Operating current
The measurement of amperage that an electrical device needs after the device has been initially powered

Rectifier
An electrical device which allows current to flow in one direction only. It converts AC current to DC

Reveal
The distance between the face of a door frame and the face of a door

Selective hold open
A door closer option which allows a door to be held open and can be enabled or disabled on demand

Silent operation
The quiet operational mode of a locking device which typically buzzes or makes other noise when energized

Single acting (door)
A door which swings in only one direction

Single pole double throw [SPDT]
The description of a form-C contact.

Single pole single throw [SPST]
A switch with only two terminals which close or open a circuit.

Stile
The vertical member of a door to which a locking device is installed

Stop
The part of a door frame against which the door closes

Time delay
A pre-set period of time when a circuit is either open or closed in order to activate a locking device.

UL listed
A listing in the UL directory for a device which has passed specific Underwriters Laboratories tests

Volt [V]
The unit of measurement of current.


[Return to the Mayflower Home Page] - [Return to the Databank Page]


© 2016 Mayflower Sales Co., Inc. All rights reserved