I happen to have experience with one of these types of doors at a company I worked at. It was only the main door. You couldn't put them on all the doors because if you did and the power went out you'd be locked in the building. I was most impressed with how impossible it was to open the door when it was locked down. I'm 6 feet tall and at the time like 250 lbs. It didn't budge one inch.
Being curious I asked how it worked etc. I guess some people do make them the other way but it doesn't seem very useful if cutting the power takes it out. Not to mention wouldn't holding the door closed with constant electricity waste a crap-ton of money?
That was a joke.
I don't know how the military and govt. systems work.
But... in our country it works the opposite way. There's a iron panel on the door, the electromagnet disengages when the credentials are right.
Or the power foes out.
Don't ask me why. I chalk it up to cheap Chinese shit. I can open the door to our office by just removing the fingerprint unit and shorting two pins.
It's bullshit. :D
We used to kick the bottom of the door and the ripple would cause the magnet at the top to disengage. Worked to get into office buildings.
I happen to have experience with one of these types of doors at a company I worked at. It was only the main door. You couldn't put them on all the doors because if you did and the power went out you'd be locked in the building. I was most impressed with how impossible it was to open the door when it was locked down. I'm 6 feet tall and at the time like 250 lbs. It didn't budge one inch.
Being curious I asked how it worked etc. I guess some people do make them the other way but it doesn't seem very useful if cutting the power takes it out. Not to mention wouldn't holding the door closed with constant electricity waste a crap-ton of money?