Keeping Electric Locks Powered Up

In April’s “Fire Side Chat” we talked about assuring ready, rapid egress in the presence of electric locking mechanisms when there’s a fire.

The need for integration between fire alarm system and electrically-controlled door locks is not an option — it’s mandatory under Section 1008.1.3.4A(4) of the International Residential Code, 2000 Edition; as well as Section of Life Safety Code, NFPA 101, 2003 Edition, published by the National Fire Protection Association. That is, providing the local authority having jurisdiction (AHJ) enforces it.

In April’s story, we talked about loss of house power and the automatic unlocking of all doors equipped with electric locks, per Sections 1008.1.3.4(2) and 1008.1.3.4(3), ICC, 2003. What we didn’t talk about. however, was the issue of secondary power for the electric locking devices on these doors. Code Clashes With Security Mission
In the past, many fire alarm code practitioners assumed that Section of NFPA 72, 2002 Edition, meant the use of secondary power was simply forbidden. Many continue to interpret the code as such.

“NFPA 72 prohibits electronic door locking devices from being kept in the ‘locked’ position by a secondary power source, when primary power fails,” says Charles Aulner, president of the National Training Center of Las Vegas ( “This requirement includes any secondary source that would keep the doors locked and inhibit exit from the building.”

The way this section is written, Aulner is correct. Section says, “All exits connected in accordance with shall unlock upon loss of the primary power to the fire alarm system serving the protected premises. The secondary power supply shall not be utilized to maintain these doors in the lock- ed condition.”

But what about the general security of such a facility? NFPA 72 and other codes do not appear to be concerned with security at all.

“NFPA 72 is simply reiterating the requirements of other codes and standards as it does with smoke control [mechanical code], elevator recall and shutdown [elevator code], power [NFPA 70 and 110], and the list goes on and on,” says Michael Baker, a fire code expert and consultant in Gladstone, Ore. ( “The building code requirement, in this case, is to allow free egress from within a structure. The exception is to lock the door so long as it is unlocked in the event of a fire.”

According to A-, the reason for NFPA’s stance relates to the potential for fire alarm failure.

Addendum A- says, “A problem could exist when batteries are used as a secondary power source if a control unit having 24 hours of standby operating power were to lose primary power and be operated for more than 24 hours from the secondary power source (batteries). It is possible that sufficient voltage would be available to keep the doors locked, but not enough voltage available to operate the fire alarm system to release the locks.”

What prompted me to investigate this further with NFPA were two things. First, in practice I have never witnessed electric locking devices in the field connected to the secondary power supply of a fire alarm control panel (typically rechargeable batteries). In fact, I’ve powered electric locking devices using a dedicated access control secondary power supply and received the nod of approval from the local AHJ every time. Evidently I’m not alone.

“I have never seen the fire alarm panel’s batteries used for backup power with electric locks. But usually the company that installs the fire alarm system is not the same one that installs the access control system,” says Dug Miller, vice president of sales with Coactive Systems Inc. (CSI) of Canton, Ohio.

The Fire Alarm-Lock Connection
Knowing the code references that pertain to electrically locking devices and fire alarm interconnection is not always enough to get the job done. Fire alarm technicians must know how to interface the two. Understanding how to combine code requirements with available technology is important.

According to the National Training Center (NTC) Brown Book on “Fire Alarm Systems Design & Installation,” authored by Aulner and Bryan McLane, “The release may be accomplished by fire alarm connections to the power supply, or by directly interrupting the power to the lock. The doors must unlock prior to or concurrent with the activation of local notification in the area. All exits must unlock in the event of loss of primary power to the fire alarm system.”

To perform this interconnection, look for a built-in relay inside the fire alarm control panel. If one is not available, check with the manufacturer whether it has an approved, listed relay for use with the fire alarm control panel you are using.

The easiest way to disconnect power to electric locking mechanisms involves the use of a relay inside the fire alarm panel itself (see diagram above). Externally-mounted relays can be used to achieve the same end result. In some cases, addressable relay modules will work well.

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