An electromagnetic lock is a locking device that consists of an electromagnet and armature plate. By attaching the electromagnet to the door frame and the armature plate to the door, a current passing through the electromagnet attracts the armature plate holding the door shut.
Unlike an electric strike, a magnetic lock is a non-latching type of device, and it also has no integral mechanical means of unlocking it. This limits the possible applications for electromagnetic locks to those situations not requiring a positive latching device and where a direct non-electronic but mechanical means of unlocking is required (such as in a Fire-Rated opening)
It is almost a universal requirement that the opening always provide free egress, although certain notable exceptions (generally referred to as special locking arrangements) have made their way into the building codes and are seen far more frequently these days.
Typically the same requirement for mechanical means of unlocking also includes that the means to unlock is on the door, requires a single hand/arm motion; and is universally recognized as how a person would open a door (such as a lever or an exit bar). Also typically required are that the lock be fail secure (will remain locked if power is removed)
Electromagnetic locks are always intrinsically failsafe. When the power to them is removed, the magnetic field vanishes, and they no longer are securing the door. This feature creates two secondary consequences. For certain security applications, removal of power to the lock creates a security breach, and in the interests of life safety, the possibility that the means to remove the power might be compromised creates an unacceptable hazard to building occupants.
Building Codes and Fire Marshals favor positive latching locking devices because over time they have proven to save lives. By remaining latched, positive latching doors mitigate the spread of smoke and fire, therefore allowing occupants more time to escape. Positive latching doors also protect first responders from premise fire induced explosions creating flying projectiles out of perimeter structure doors.
Despite these constraints, maglocks represent an important product group to electronic security and access controls.
Of the terms used in electronic security and electromagnetic locks, “APPROVED, LISTED, RECOGNIZED and CERTIFIED” are among the most important, and most mis-used and misunderstood.
UL (Underwriter’s Laboratories) is an independent, not for profit, testing laboratory. They perform tests on devices. Once a device has been tested and passes UL testing it will either be UL Listed, UL Recognized or UL Certified.
UL Listed means that the product has passed testing. The UL label will show the category that UL has employed for testing. A panic bar might be labeled “Listed Exit Device.” A magnetic lock might be labeled “Listed Auxiliary Lock.”
The label will also include a four letter code, for example “GWXT,” which is assigned based on the product category and type of tests. It is important that a device is listed for the application in which it is used.
Securitron’s Model 62 Magnalock® became the first electromagnetic lock to pass a battery of UL tests and achieve the status of UL Listing in 1984. UL created a new code (FWAX2) for this device.
This fact that Securitron was first to achieve UL Listing is interesting when you realize that Irv Saperstein, the founder of Locknetics, had built the first magnetic lock in 1969 and in 1983, there were three major players in the electromagnetic lock market; Securitron, Locknetics and Security Engineering.
UL Recognized is the status UL grants to a component which needs to be combined with other components to create a finished product. UL Certified means a product that has been successfully tested by UL to a non-UL standard, most often an ANSI standard.
The locksmith must determine the hierarchy of LAHJs for a particular situation, and to take the necessary steps to assure compliance.