When an access control application uses a sensor detecting an approaching occupant to release a lock for egress, the model codes require an auxiliary push button which will also release the lock. This type of system is often used with electromagnetic locks, and the codes also require the locks to release upon actuation of the fire alarm/sprinkler system, and upon power failure. This application is the only one where the model codes require an auxiliary switch beside the door – the switch is not required for doors with controlled access/free egress, delayed egress, controlled egress, or mag-locks released by a switch in the door-mounted hardware (local codes may vary).
With regard to the auxiliary switch, the International Building Code (IBC) says this:
The doors shall be arranged to unlock from a manual unlocking device located 40 inches to 48 inches (1016 mm to 1219 mm) vertically above the floor and within 5 feet (1524 mm) of the secured doors. Ready access shall be provided to the manual unlocking device and the device shall be clearly identified by a sign that reads “PUSH TO EXIT.” When operated, the manual unlocking device shall result in direct interruption of power to the electric lock—independent of other electronics—and the electric lock shall remain unlocked for not less than 30 seconds.
NFPA 101 – Life Safety Code says this:
Door locks shall be arranged to electrically unlock in the direction of egress from a manual release device complying with all of the following criteria:
(a) The manual release device shall be located on the egress side, 40 in. to 48 in. (1015 mm to 1220 mm) vertically above the floor, and within 60 in. (1525 mm) of the secured door openings, except as otherwise permitted by 220.127.116.11.2(3)(c).
(b) The requirement of 18.104.22.168.2(3)(a) to locate the manual release device within 60 in. (1525 mm) of the secured door opening shall not apply to previously approved existing installations.
(c) The manual release device shall be readily accessible and clearly identified by a sign that reads as follows: PUSH TO EXIT.
(d) When operated, the manual release device shall result in direct interruption of power to the electrical lock — independent of the locking system electronics — and the lock shall remain unlocked for not less than 30 seconds.
These requirements are clear regarding the location of the switch, that the switch must be marked “PUSH TO EXIT,” and that the switch must be readily accessible (not behind a break-glass panel). These sections also state that the switch must directly interrupt power to the lock – independent of the other electronics – and must remain unlocked for at least 30 seconds.
So here’s the question. One of the ways to accomplish the 30-second unlocking – independent of the access control system electronics – is to use a pneumatic switch. But the model codes don’t specifically prescribe the type of switch that must be used.