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Basically what the title says, you'll find many buildings have these types of door locks Magnetic lock which can usually be opened by using a RFID token. While this example photo is glass, lets assume that the door is steel/unbreakable.

In the even of fire what does/should happen to them?

From a security standpoint, any condition that throws open all the doors is probably a bad one, but if they don't open/fail then there's the possibility for loss of life in the event of a real fire.

Is there any guidance around this?

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  • @Iszi - Hat-tip ;)
    – NULLZ
    May 31, 2013 at 1:40
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    Fire codes will typically dictate that they fail open, and unlock. Life is more precious than anything else you may be protecting.
    – Xander
    May 31, 2013 at 1:48
  • @Xander That doesnt apply to military/law-enforcement secrets where the loss of information may lead to larger loss of life. (just being difficult for the sake of it :P )
    – NULLZ
    May 31, 2013 at 1:57
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    My thought is that that falls into the realm of movie plot threats. In real life, if you're protecting secrets that critical with nothing more than door locks, you're doing it wrong. :-)
    – Xander
    May 31, 2013 at 2:01
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    The specific type pictured is an electromagnetic lock, which is inherently fail safe. Electric strikes can be either fail safe or fail secure. Here's a good description of when each type is used: idighardware.com/wordpress/wp-content/uploads/2012/05/…
    – Thaeli
    May 31, 2013 at 5:14

2 Answers 2

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This is a very interesting question, I've come across this when a client was designing a fire-code-compliant office space. The client's work was related to the defence industry and the office space had two rooms with highly classified contents.

Now, of course, if you're a 3-letter government agency, you can disregard whatever laws you want, but let's assume that we want to follow the legal procedure.

The laws are clear when it comes to building code and fire safety (in all countries it's pretty much the same, but I'll quote the one from the United States). The National Fire Protection Association Life Safety Code 101 says

Locks, if provided, shall not require the use of a key, a tool, or special knowledge or effort for operation from the egress side.

So to comply with the laws, the client built the rooms on the side of the hallway, making them impossible to use in the path of egress, then installed a big red button that would mechanically open the door from the inside. Behind the door there's a turnstile gate (though a very different model) that would only allow egress but not entry.

The idea is simple. If your room provides a step on the egress path, then by law it must be opened in the direction of the egress path. So it all comes down to thinking about security when designing the building.

I've found this image online and I added the red arrows and text to illustrate the point (those aren't really exits and fire exits)

enter image description here

So, Should magnetic locks automatically release in the event of a fire alarm? The answer is, it depends.

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  • Does 'egress path' mean ANY exit, or only exits that are designated fire exits?
    – NULLZ
    May 31, 2013 at 6:24
  • @D3C4FF Any path that could be used to reach any exit.
    – Adi
    May 31, 2013 at 6:26
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    Humans panic in fires or explosions and exit via the same path they enter (typically passing exits on the way). They pile up at locked doors and die. They typically do not push the big red button. Risk assessments should be based on scientific observation.
    – zedman9991
    May 31, 2013 at 12:13
  • @zedman9991 Sure, we all like to live in a world were everything is tested, studied, researched, and double tested, but the reality is different. Authorized personnel with access to classified areas usually receive a certain level of training for such situations. For normal buildings like regular offices, studies on human behavior can be applied, but in highly-controlled areas (Military, Intelligence, etc.) human behavior is modified by training.
    – Adi
    May 31, 2013 at 12:27
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    @zedman9991 I think you're right, I haven't made it clear enough. My answer to the OP's question "Should magnetic locks automatically release in the event of a fire alarm?" is: It depends on the location of the door, the important thing is that the door can open easily to allow a path in the direction of exiting the building.
    – Adi
    May 31, 2013 at 12:43
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Perform a risk assessment. Decide based on the importance or protecting the assets vs human life. This may also be a room by room basis. It would have to be of very high security to require a fail close scenario, and there should be clear acknowledgement from those affected that they understand the risk (either by course of their job -e.g., NSA computer lab - or by agreement/contract).

There may also be legal requirements and fire department regulations as noted in comments above.

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