Magnetic lock systems have only been in existence for a relatively short time. It is generally acknowledged that the modern electromagnetic lock was invented in the late 1960s. Basically a magnetic lock, or maglock, consists of an electromagnet and an armature. When electricity is applied to the electromagnet, it attracts the armature. Usually the maglock is attached to the door frame and the armature is attached to the door. A small amount of movement is designed into the armature so it can shift slightly as needed to form a complete bond with the maglock as the door is closed. 12-24 volt DC current is required and electrical consumption for most maglocks is about equal to a conventional 60 watt light bulb.
Maglocks have several advantages versus mechanical locks. They are quiet, durable and have no moving parts to wear out. Maglocks are not affected by back pressure such as if persons push or pull the door before it is released.
Maglocks are easy to install. Lock installations on gates, sliding doors or other unusual opening can often be solved more easily with a maglock.
Maglocks are electrically operated, allowing for special functions such as unlocking by use of a keypad or card system, door ajar status, motion detector, delayed egress or delayed relocking, alarm notification of an attempted opening plus a timer can be used to set lengthy locked or unlocked time periods.
Maglocks can also be wired into a fire alarm system to release the door during an emergency. Maglocks are fail-safe and release quickly as soon as the power is removed. At least one manufacturer, Securitron, has a new M680BDC maglock which incorporates a video surveillance camera.
One disadvantage is that maglocks require continuous power in order to remain locked. Therefore the door will become unlocked in case of electrical system failure. A battery backup system can be used to prolong the locking cycle during an electrical failure.
Most installations by locksmiths will be aftermarket installations on existing doors. Most maglocks are installed at the top of the door jamb with the armature mounted on the door adjacent to the maglock. Existing doors should be checked to be sure that they are rigidly constructed so the door will not flex as people pull or push at door handle level. Maglocks should always be mounted on the secure side of the door to prevent vandalism.
Some magnetic lock manufacturers offer maglock systems which are mounted on the vertical part of the door jamb. This type of maglock solves the flexing question but the hardware extends out slightly into the door opening. Check to see that your installation does not violate Americans With Disabilities Act (ADA) requirements for door opening dimensions before installing. Before installing any magnetic lock system, check with the local authority have jurisdiction (LAHJ). As example, for many years the City of Chicago had restrictions against magnetic locks because there was no way to mechanically disconnect the lock in an emergency.
Maglocks are available in several different sizes and types. Holding strength can vary from 275 lb holding force to a 2900 lb holding force. An approximate holding force of 1200 lbs is adequate for most single door installations. Pairs of maglocks mounted in a common enclosure also available for double door installations. Shear locks are designed magnetically hold against a sideways (shearing) action such as in a sliding door installation. An interesting Adams-Rite MS1500 maglock incorporates a combination magnetic and mechanical design. Two spring-loaded mandibles clamp on the armature to provide a 4000 lb holding force.
For More Information
Maglocks can provide a simple-to-install, flexible locking system which offers many options. A beginning list of manufacturers (with telephone numbers and web sites) includes:
Adams Rite: 800-872-3267, www.adamsrite.com
BEA: 800-523-2462, www.beasensors.com
Important: Before installing electronic locks, it is important to check with the “Local Authority Having Jurisdiction” (LAHJ). An electromagnetic lock is designed to provide security for a...
Electromagnetic locks are sometimes regarded as an “idiot-proof locking solution” for unskilled installers or for use on problem doors.
Take a glimpse inside the manufacturing process for a magnalock.