I often get asked about the strongest locking system for a condominium front door. This is the door shared by all residents of the building that usually takes you into the main lobby area.
Magnetic locks always come to mind as the super strength lock that does the job. These locks can be activated in a multitude of ways including key fobs, swipe cards and, of course, biometric readers. Other variations and improvements on mag locks have been developed over the years. The most remarkable is the shear lock. This lock has an armature that does not directly pull off the face, but the load is instead in shear, like a mechanical stop.
The shear magnetic lock allows a door to swing in both directions, as opposed to the original direct pull type that normally works either in an in-swing or out-swing configuration.
The basic magnetic lock or mag lock usually consists of a rectangular shaped magnet that is installed along the top of the door frame. This coincides with a metal plate that is fastened to the door. When power is supplied to the magnet it creates a magnetic charge that keeps the two metal plates anchored together. The average mag lock will not break the hold unless more than 1,200 pounds of force is brought between the two plates.
In other words, Superman himself couldn’t pry these two plates apart. The only thing that will allow this locking mechanism to release and open the door is an interruption in the power that is being supplied to it.
Electronic locks are described as either fail safe or fail secure. So what’s the difference?
- Quite simply, fail-safe locks are locked when energized and fail-secure ones are unlocked when energized.
- Fail-safe locks require power to lock. When there is an interruption of power by an access control user or power failure, the door will unlock. These locks are used on fire-rated exit doors and high-rise building stairwell doors.
- Once somebody activates the fire alarm, the locks are automatically released.
- Typically used for high-security applications, fail-secure locks are not permitted on fire-rated doors because they do not unlock during an emergency or power loss.
- If a mag lock is used on an interior door that’s not a designated fire door, a battery back-up power supply could be used to provide continuous power to the lock to ensure it is secure at all times.
- Mag locks range in strength from a couple of hundred pounds of force for applications where brute force is not a threat, to magnets which hold under thousands of pounds of force for high-security areas.
With a mag lock, the door is always locked from both sides which makes it an excellent choice for those high-security areas. This lock must be activated with either a key fob or swipe card when leaving and entering the building. Once swiped the reader will interrupt the power to the lock for a few seconds and allow the door to be opened.
A question I often get asked is, how much power do mag locks use? Today’s mag locks don’t use much power. As a matter of fact, several mag locks can be kept in operation using less electricity than a 60-watt light bulb. But keep in mind that the amount of electricity used is mainly related to the holding strength of the mag lock.
Contrary to popular belief, the mag lock does not require much maintenance. One thing you have to remember is to keep the mating faces of the armature and magnet clean, making sure no abrasive materials are used to clean the faces. Do not spray the magnet or armature with any chemicals, such as lacquers, as the release of the mag lock may be compromised.
By Frank Fourchalk
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