Electric Locks Should Be Tied Into the Fire System

Recently, an unhappy fire technician wrote me about how a local building inspector failed to pass his fire alarm system because of a problem with another company’s access control system. Even more frustrating, the security dealer that installed the access system was not in a hurry to fix his problem, which unfortunately prolonged the time it took the fire tech to gain final approval.

To the building owner, it was just as frustrating because it delayed the opening of his building. According to the fire tech, the building inspector said the deficiency involved the use of fail-secure locks whereas code calls for fail-safe models. Also cited was a lack of integration between the structural fire alarm system and the electronic access system.

In a nutshell, fail-safe locks work in such a fashion that when operating power to the locks fail, they automatically release the door. Also, when integration takes place, the fire alarm system will cause the electric locks to release when a fire is detected.

In this case, there was no connection between the fire alarm system and the electric locks throughout the building. Thus, if a fire were to take place, it would be impossible for the occupants to egress the building in accordance with Life Safety Code, NFPA 101, 2000 Edition.

The use of electric locks is allowed where noted in other areas of the code. However, when such is the case, there are a multitude of dos and don’ts that the fire technician must adhere to. “Where permitted in Chapters 11 through 42, doors in the means of egress shall be permitted to be equipped with an approved entrance and egress access control system” (Section, NFPA 101.

That same section and others within the code provide the criteria that must be met in order for the end user to employ the services of electric locking devices. Learning what they are will help you become a better-equipped fire alarm technician.

Discerning Fail-Safe vs. Fail-Secure
As pointed out previously, the first consideration is whether the lock meets the criteria of NFPA 101, which details the parameters of using fail-safe locks. The central issue behind this type of lock is the ability of the occupants to readily egress a burning building when electrically controlled locks are employed.

Section 7- addresses what the electric lock must do when operating power to the lock mechanism is lost, as in a power failure situation (transformer power) or the failure of the batteries in a back-up power supply. The code states: “Loss of power to the part of the access control system that locks the doors shall automatically unlock the doors in the direction of egress.”

In the case of a fail-secure electric lock, the door will remain in a secure condition when said power disappears. This is because the lock mechanism requires power to disengage the latch so the door can be opened. A fail-safe lock, on the other hand, allows the occupant(s) to readily open the door because its locking mechanism requires power only to maintain a secure posture. In other words, when power is lost, the mechanism will release, allowing the door to freely open.

For clarification, the issue of operating power, as outlined in Section 7- of NFPA 101, relates to the voltage that powers the electric lock, rather than the access control system as a whole. This might involve raw 24VAC from a plug-in, step-down transformer or a series of batteries contained in an ADA (Americans With Disabilities Act)-compliant power supply.

One way to identity the type of lock is to look at the specifications. It should tell you whether it is fail-safe or fail-secure. If it does not, look for the phrase, “intermittent-duty” or “continuous-duty.” If the lock is an intermittent-duty model, you might suspect it is a fail-secure model. On the other hand, if the specification mentions continuous-duty, then you might suspect fail-safe.

Code Mandates Need for Integration
The second reason why this fire alarm company’s fire system did not pass muster involved the lack of integration between the electric door locking mechanism(s) and the fire alarm system, which was installed by a second company. Although it would seem unfair that the authority having jurisdiction (AHJ) would fail to pass one company’s fire alarm installation because of a second company’s incompetence, the AHJ is well within his or her rights to do so.

NFPA 101 calls for the interconnection of the electric locking devices with the automatic fire alarm system and sprinkler system, if one is employed. This provision can be found within Section, Access Controlled Egress Doors, subsection (c) and (d).

Subsection (c) says: “Activation of the building fire-protective signaling system, if provided, shall automatically unlock the doors in the direction of egress, and the doors shall remain unlocked until the fire-protective signaling system has been manually reset.” Subsection (d) covers automatic sprinkler and fire detection systems and essentially states the same thing.

Interconnection is most often accomplished by supervised relays in the field. The normally closed portion of a Form C relay is used to allow power to pass, thus powering the electric locks – until a fire is detected by the fire alarm system. When a heat sensor, smoke detector or some other means detects such a fire, the fire alarm must have the capability to disconnect operating power from the lock mechanism, thus allowing the occupant to freely egress the building.

There is an easy way to accomplish this task in a locking system that employs a centralized, ADA-compliant power supply. Many of these power supplies come with a set of contacts for the fire alarm system.

Simply connect a supervised relay from or in the fire alarm panel to the contacts and the ADA supply will disconnect power to the locks. The second way, if the power supply does not have a set of fire alarm contacts, is to use a supervised relay at the central point of generation.

Additional Considerations to Be Met
There are other life-safety issues to consider when installing a fire alarm system besides the type of electric lock employed and the integration of both electric locking system and fire alarm.

For example, in Section 7-, NFPA 101, 2000 Edition, it specifies that installers be required to use egress-type motion detectors to automatically release an electric lock when someone approaches the door. In addition, there must be a manual means of egress available, other than the egress motion detector and interconnection with the fire alarm and/or sprinkler system.

“A sensor shall be provided on the egress side and arranged to detect an occupant approaching the doors, and the doors shall be arranged to unlock in the direction of egress upon detection of an approaching occupant or loss of power to the sensor” (Section 7-[a], NFPA 101, 2000).

In most cases, the common way that the egress motion detector interacts to release the door is through the request-to-exit (REX) input in an access controller unit or the head-end system. A relay within the controller or head-end then disconnects power to the continuous-duty lock, thus releasing the door so the occupant can immediately egress the structure.

Within subsection (c), it also states that a mechanical means of disengaging operational power is a must. The way a manual egress device accomplishes this task is by mechanically interrupting power to the lock. This mechanical action is performed within the manual egress device itself, not via the REX circuit in the access controller or head-end.

In practice, the manual, mechanical means used to disconnect the electric lock from its source of operating power are usually achieved using a double-pole, double-throw momentary push-button switch (see illustration on page 42). Keep in mind that Section states: “The doors shall be
arranged to unlock in the d

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