Why do we use facilities with EPO's?

Thu Jul 26 10:24:11 UTC 2007

On Wed, Jul 25, 2007 at 07:47:48PM -0400, David Lesher wrote:
> I've never designed or looked into a EPO installation; but I'm
> astonished such does not use a Normally-Closed pushbutton in a
> fail-to-off circuit.
> 
> Similarly...
> 
> If you have electric locks on your exit doors; every installation
> I have seen has a couple of such aspects:
> 
> a) You must have an exit override. If an electric strike, an
> interior knob is good. If a [Locknetics-style] mag-lock, you
> need an exit button.  That button SHALL be a NC pushbutton in
> series with the magnet. [In other words... No, you can't have
> the pushbutton connected back to some controller box on the 3rd
> floor where it generates an interupt that will drop the lock
> power...  or it's supposed to...]

Sorry I've seen a few that dont have an exit override.

> b) When the building fire drop is pulled, you SHALL drop the lock
> power to the mag locks.

I've seen at least one that does not do this.

> And while local fire codes vary widely; given those were in the
> rules for a USG SCIF I worked in; I somehow doubt you'll be able
> to get more lenient treatment based on the import of the data
> center's operation.

That depends on a bunch of criteria.. override buttons and failure when power goes out create significant security risks. If you are a bank or have very secure data then you might consider these to be ways in which an intruder might compromise your security.

>From what I've seen tho, when you remove the ability to exit in this way then you also find you have a lot of control procedures imposed to avoid unnecessary risk to employees or visitors.

Steve