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Comment by userbinator | Hacker News Reader

I'll amend that to say "can't be opened without the application of unreasonable force". The possibility of a power outage causing the same scenario also worries me.

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That's called pushing on the crash bar or twisting the handle/knob so it opens. It's fire code for a reason.

A previous employer's office had electronically locked doors (magnetic, I think?). The studio head said that they were designed to 'fail open' (i.e. unlocked) in the case of a power outage. Then the power went out a couple weeks later, and the doors were locked.

Oops.

Our emergency exits were old-fashioned analog doors and still worked, at least.

I once worked somewhere with magnetic locks and a decent shove easily opened the door. We did this for smoke breaks as our magstripe cards noted every time we left the control room.

How did you get back in? Sounds like a security hole.

"a decent shove opened the door"

Easy. Just prop it open.

I've installed these doors. It's easy to mess up as the switch to determine the failure mode is part of the equipment. This was an untested install.

How does a mag lock fail closed with no power? Or are you talking about one of those strikes near the latch?

Batteries, I would guess. It's pretty bad if your security system allows entry to people when there is a black out.

Electromagnet locks --- which have an electromagnet in them to keep the door closed and are surprisingly strong for their size --- are truly fail-open since loss of power means loss of force keeping the door locked, but those doors might've also had an additional fail-closed type of electric lock that requires a brief pulse of power to open.

https://en.wikipedia.org/wiki/Electromagnetic_lock

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