Last week someone called me with a “quick question” about a double egress pair in a hospital. The hospital wanted to install shear locks on a pair of double egress doors, to use during emergency lock-downs. Unfortunately, as some of you have figured out by now, I don’t usually have a quick answer. There are actually two issues here:
1) If there’s a pair of cross-corridor double egress doors, that’s usually a clue that egress is required in both directions. Not 100% of the time, but almost. If you install an electromagnetic lock on an egress door, you also need a motion sensor and push button to unlock the door from the egress side, and the door has to unlock upon power failure and fire alarm. Since both sides of a double egress pair are usually required for egress, that means that both sides of the opening would have motion sensors and therefore, no security. In some cases, a variance may be granted by the code official, but the facility would have to go through the process of applying for one and the chances of receiving the variance aren’t great.
2) The second problem with this application is the use of shear locks. Shear locks are one of my least favorite locking devices (which implies that I have a list of favorites, which means that I’m a total dork), and my opinion is shared by just about every security consultant I’ve ever met. A shear lock has an electromagnet concealed in the frame head, and a steel armature in the top of the door. When the door closes, if the door, frame, magnet, armature, and all the stars in the sky are aligned, the magnet energizes and pulls the steel armature up to meet it, creating the magnetic bond which locks the door. The chances of alignment a year or two after installation are about as good as the chances of receiving the variance. This jeopardizes security and requires extra maintenance, not to mention the noise of the steel armature meeting the magnet. Architects like them because they’re concealed, but they’re not reliable over time.
My recommendation for this application was that they may be able to use delayed egress mag-locks or exit devices, and that direct-hold mag-locks would be preferable to concealed shear locks. Maybe not as pretty, but beauty is in the eye of the beholder, right?