Why do we use facilities with EPO's?

Wed Jul 25 21:49:35 UTC 2007

>Seems like the EPO should be a logical AND with the fire alarm system - 
>it only works AFTER you have an existing fire alarm in the building.

No, no.  If the fire alarm system fails, the fire responders need
to be able to hit the EPO and be sure that it works anyways.
It has to be an absolute - firefighters have to know that the
thing they hit was the only, and right, thing, and that they
aren't going to die because they sprayed water on an energized
but on fire electrical system backed by a 120 KVA UPS or some
such.

Also, one should not wait for fire alarms to go off to de-energize
a room in the clear presence of an electrical fire or major short.
Preventing the fire is better than putting it out.

Telco central offices are somewhat of an exception in many ways,
but just about anyone else should have a real live EPO.

-george william herbert
gherbert at retro.com