Access Control: Delivering Security, Life Safety, and Convenience

Specifying appropriate door and hardware components for building projects
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Advertorial course provided by ASSA ABLOY Door Security Solutions
T.J. Gottwalt AHC/CDC, CSI, CCPR

Strikes and Maglocks

Electric strikes or magnetic locks can be used to further regulate who passes through access points, providing an even greater level of protection.

Electric strikes are door locking devices, usually solenoid-operated, that will unlock the door when electrical power is applied to them. An opening that requires a person to be "buzzed in" is equipped with an electric strike. The buzzing sound is created when a button is pushed, sending an AC current through the device. This action disengages the device and allows the door to open. The operation just mentioned is a fail-secure mode of operation, the most common function of an electric strike. A fail-safe configuration will operate in the reverse condition; normally locked when power is applied and unlocked when power is interrupted. If desired, the buzzing sound can be eliminated by using a DC power source.

Magnetic locks are electromagnets that mount on the fixed frame, and a strike plate that mounts on the moving door or gate. When the door closes, the strike plate automatically aligns with the magnet. The magnetic force then takes over, strongly securing the door. Release is achieved by switching off the power to the magnet. Magnetic locks are available in a range of holding forces. Facilities that demand greater security, such as a detention facility, will need magnetic locks with holding forces that approach 2,000 pounds.

Since electricity is required to power the magnet, all magnetic locks are fail-safe unless they are equipped with a back-up power supply. Magnetic locks operate on DC power and, unlike electric strikes, are silent when locked or unlocked.

Both electric strikes and magnetic locks are commonly operated with a push-button switch, making them ideal for personnel-monitored openings such as office suites and hospital ward entrances. Local code authorities should be consulted before applying magnetic locks to openings, as there are specific regulations governing their application.

While technically not locks, automatic operators are an important component in an access control system. With the simple push of a button, a door can be opened, held open to allow passage, and then closed. Most buildings have at least one entrance that is required to be accessible in such a manner to meet ADA and other accessibility codes. These entrances are not only for physically disabled persons, but for many situations when a person may not have his or her hands available to push or pull a door open.

Switches

The types of switches that can be used in conjunction with electromechanical hardware add to the diversity of access control options. Switches send a signal that activates or deactivates the lock. Several types of switches can be used in an access control system. Available options include push buttons, keypads, key switches, signal switches, card readers, electronic key readers, motion sensors, and biometric readers.

Push button switches are located at the opening or are remotely operated by a person. A simple push of the button unlocks the door and allows access.

Keypads require a numeric code to activate the lock. A keypad can be programmed to uniquely identify each user or to function similar to a combination lock, where each door, rather than the user, has a unique code. Keypads can serve as the exclusive identification device, or they can be used in conjunction with other credential switches, such as a card or proximity reader.

Key switches are mounted at the opening and are operated by a conventional key. The device allows authorized personnel to control or signal from various locations within a facility.

Signal switches are mounted within the lock, exit device, door frame, hinges or magnetic lock and are used to initiate operation of the system, monitor the state of the doorway (open or closed) or request to exit. Every door in an access control system needs to include a door position switch in order to monitor the status of the door (open or closed). Whenever a door has a door position switch, the system needs to know when it is allowable for someone to exit; therefore, a switch is required as a "request to exit", also known as REX. This can be a switch on the inside lever of a mortise lock, a switch in the push rail of an exit device, a touch sense bar or a motion sensor.

Card readers are probably the most commonly used access control switch. A variety of technologies are available with card readers, including magnetic stripe, proximity, and smart cards.

Electronic keys offer the same convenience as conventional keys. Older versions of this technology relied upon direct contact with a mated surface. Newer systems use passive technology and are gaining popularity.

Motion sensors operate by way of input from an infrared sensor that detects heat, a motion sensor that detects movement, or a combination of both.

Biometric readers authenticate the identity of system users by scanning unique physical characteristics, such as fingerprints, hand prints, retinas, or facial geometry. The readers can be mounted by the opening or incorporated into a handheld proximity device. Biometric readers usually require a large database of user information in order to authenticate each user.

 

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Originally published in Architectural Record.
Originally published in December 2005

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