Quite a few questions about battery back-up were asked during my webinars last week, so I think this is a good time to clarify this issue and also to get some feedback from you. Here are the Quick Questions for today’s post:
Is it acceptable by code to provide battery back-up for an electromagnetic lock? What about other types of electrified hardware?
This is an issue that is not specifically addressed in the model codes, so the answers depend somewhat on the interpretation of each Authority Having Jurisdiction (AHJ). I am not an AHJ, so this is the way I’m interpreting the code requirements but someone else may have a different view. I’d love to know what you are hearing in the field, and if you’re an AHJ, please weigh in by leaving a comment!
This topic was addressed in my very first Decoded column for Doors & Hardware magazine (more than 100 columns ago!). The article talks about NFPA 72 – Fire Alarm Code, and how it addresses electrically-locked doors. The code has been updated since then, but I think the intent remains the same. From the 2019 edition of NFPA 72:
21.10.3* Secondary power supplies of fire alarm control units shall not be utilized to maintain means of egress doors in the locked condition unless the fire alarm control unit is arranged with circuitry and sufficient secondary power to ensure that the means of egress doors will unlock within 10 minutes of loss of primary power.
A.21.10.3 A problem could exist when batteries are used as a secondary power source if a fire alarm 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 would be available to operate the fire alarm control unit to release the locks.
According to the model codes, electromagnetic locks are required to unlock upon loss of power; mag-locks released by a sensor are also required to unlock upon fire alarm activation. My interpretation, based on what I’ve heard from AHJs and others, is that if an electromagnetic lock has back-up power, it must be the same back-up power that powers the fire alarm system.
In my opinion, this would not apply to access-control doors that allow free egress at all times. For example, if a door has a reader on the outside and a lever handle or panic hardware that allows egress, independent battery back-up for the electrified hardware (separate from the fire alarm system) would have no impact on egress. But for mag-locks, delayed egress locks, or controlled egress locks that have back-up power, the same system should provide back-up power to the fire alarm. This ensures that the doors will release upon fire alarm activation, as required by the model codes.
Remember, some AHJs or local codes may have different requirements. Some AHJs do not allow battery back-up for electrified hardware AT ALL, and some don’t even have it on their radar or check to see how the system functions. It’s always best to get approval from the local code officials before the system is installed.
What do you think? Please share your insight!
You need to login or register to bookmark/favorite this content.
Lori,
I have forwarded your question/explanation to a friend of mine, Warren Olsen who Chairs one of the sections of NFPA 72. I’m hoping he gets back to me or to you quickly. He seems to be very busy traveling across the country but who knows with COVID???
One of my favorite topics.
Technically, the IBC would indicate that backup power from batteries (or generators for that matter) would be permitted: In 1008.1.9.7 (delayed egress) it says, “The doors unlock upon loss of power controlling the lock or lock mechanism”. In 1008.1.9.8 Access-Controlled Egress Doors, you see this mentioned in two places: 1)”The doors shall be arranged to unlock by a signal from or loss of power to the sensor.” and 2) Loss of power to that part of the access control system which locks the doors shall automatically unlock the doors. 1008.1.9.9 Electromagnetically Locked Egress Doors para 4 says, “Loss of power to the listed hardware automatically unlocks the door.” Nowhere does it mention the source of the supply; so, it would seem that any power supply could be used. I am a security guy so I may be biased here.
Generally unlocking is required by “loss of power” and I believe it was intentionally written in this way to permit back up power to be used. That being said, I have had one fire marshal who would not approve back up power of ANY kind for these doors; even though seemingly permitted by the governing code at the time. Eventually, I made a complaint to his boss and the matter was resolved in my favor.
I would also be interested in what other “Greene Heads” would say how long should the back up power last and why. Lori, maybe this could be a good topic. Particularly, since there is a vast difference between the security and IT world’s definition “how long”.
My comment has a slightly different twist due to an experience. We needed to hook up some fire system devices to an existing fire alarm system years ago. We were informed by the fire division that we needed to create a.separate box for the additions since they were not part of the original UL approved design. We had not considered that our additions, which were done by a licensed fire system contractor, needed a deeper consideration of power requirements to avoid a malfunction of the original equipment
Ultimately we needed additional source of power. We always involved our AHJ and we found them to be very careful and experts.
This controversy has been a subject of debate for years . That’s why electric strikes are always a safe bet . No pun intended
I am a Building Official in the State of Missouri. We will allow the installation of battery backup power of the control unit for the electromagnetic locking hardware if the hardware also complies with section 1010.1.9.8 of the 2015 International Building Code which reads as follows:
1010.1.9.8 Sensor release of electrically locked egress doors. The electric locks on sensor released doors located in a means of egress in buildings with an occupancy in Group A, B, E, I-1, I-2, I-4, M, R-1 or R- 2 and entrance doors to tenant spaces in occupancies in Group A, B, E, I-1, I-2, I-4, M, R-1 or R-2 are permitted where installed and operated in accordance with all of the following criteria:
1. The sensor shall be installed on the egress side, arranged to detect an occupant approaching the doors. The doors shall be arranged to unlock by a signal from or loss of power to the sensor.
2. Loss of power to the lock or locking system shall automatically unlock the doors.
3. 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 lock—independent of other electronics—and the doors shall remain unlocked for not less than 30 seconds.
4. Activation of the building fire alarm system, where provided, shall automatically unlock the doors, and the doors shall remain unlocked until the fire alarm system has been reset.
5. Activation of the building automatic sprinkler system or fire detection system, where provided, shall automatically unlock the doors. The doors shall remain unlocked until the fire alarm system has been reset.
6. The door locking system units shall be listed in accordance with UL 294.
Our experience has been that the access control units are designed to shed power as the battery power diminishes. The units are programmed to shed the power going to locking equipment last, which could result in an individual being locked into the facility until total loss of battery power. By incorporating the sensor control on the egress side of the door and requiring the lock to release by loss of power to the motion sensor, this hazard is prevented.
Excelent comment!!!
I think “UL294, Standard For Access Control System Units” and “ULC S533 Egress Door Securing and Releasing Devices” actuall do. Both are considering the lock´s power supply shall have a switch wich interrups the power thugh the Fire and Alarm Switching System.
Then there are many redundance for switch off the lock system in egress – Mov Egress Sensor, Opening Device, Fire Relay System and Alarm Relay System -.
Then I think the “Back Up Batteries Bank” could be setted up to secure the ingress and the correct sensor and opening device function. Independent of Fires Power Supply System and Alarm Power Supply System -.