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@retro.com
I worked three years with the boston fire dept, albeit quite a few
years ago, and rode into many fires and don't generally remember them
being much concerned about hitting *anything* with a high-pressure
stream of water if it's on fire.
Remember all those rules you know about not using water on electrical
or chemical fires? Doesn't really count if you have charged fire hoses
and know what you're doing except in some special circumstances (they
did foam things occasionally, very occasionally, foam costs money!)
If they needed the power out, perhaps due to a gas hazard, they
generally go for the power out in the street, calling in the power co
if there's time or, well, one of the firefighters usually knows how to
cut a building's power, between them they usually know just about
everything they need to know about stuff like that.
I have no doubt if they saw an EPO and the room on fire they'd hit it
immediately, why not, as you say it can only make things safer (plus
or minus emergency lighting working but they should have their own.)
But unless there was an explosion hazard I don't remember there being
much concern. Water pressure and getting the equipment positioned and
working was a concern (after life and limb of course.)
Put another way: Between a 120KVA UPS and a gang of experienced
firefighters with charged hoses I'd put my money on the firefighters
every time.
(snip)
Put another way: Between a 120KVA UPS and a gang of experienced
firefighters with charged hoses I'd put my money on the firefighters
every time.
--
-Barry Shein
You realize the UPS systems we're speaking of are much larger? Usually 480
volt, many kVA.
Randy
FWIW, do you imagine that's terribly large for urban firefighters in
the big scheme of things, not just computer rooms?
My memory could be wrong but I remember the John Hancock building, 60
stories, pulls about 1.5MW...I remember Boston Edison mentioning this
in discussing a design I was working on of a supercomputer facility,
that we were asking for more power than the hancock building which was
ok but it presented..."challenges". Factories can pull a lot of power
also (that room was never built.)
Anyhow, once you're beyond a pea-shooter I don't think procedures for
firefighting vary a whole lot, other than some outliers.
-b
FWIW, do you imagine that's terribly large for urban firefighters in
the big scheme of things, not just computer rooms?
My memory could be wrong but I remember the John Hancock building, 60
stories, pulls about 1.5MW...I remember Boston Edison mentioning this
in discussing a design I was working on of a supercomputer facility,
that we were asking for more power than the hancock building which was
ok but it presented..."challenges". Factories can pull a lot of power
also (that room was never built.)
Anyhow, once you're beyond a pea-shooter I don't think procedures for
firefighting vary a whole lot, other than some outliers.
-b
I guess my point was that it's safer to power off a UPS system as best you
can before you shoot water at it. 
Most likely you are doing this at
somewhat close proximity, with step-down transformers nearby, etc.
An EPO not only shuts down the power feed to the UPS, but the UPS as well.
Which is a good thing.
A properly placed EPO and warning signs, as well as proper training of your
customers and vendors should minimize the risks associated with an EPO.
Look, if someone is hell bent to destroy your facility, EPO or not, they
will succeed.
Randy
I guess my point was that it's safer to power off a UPS system as best you
can before you shoot water at it. Most likely you are doing this at
somewhat close proximity, with step-down transformers nearby, etc.
Somewhat true.
An EPO not only shuts down the power feed to the UPS, but the UPS as well.
Which is a good thing.
The batteries still make pretty colors when you hit them and start bridging things that shouldn't be bridged. But if it's not on fire, it is usually avoided by the fire department.
I'm posting on this as a 17 year volunteer fire department member as well as a professional (albeit part-time, with the rest of my time spent in network ops) fire marshal for a town in PA.
EPOs are great, and as a fire marshal I like them (preventative) but they really don't figure in to the picture when I've got my firefighter hat (ok, helmet) on - because we just cut mains to everything, and generally know what we're looking at and how to handle it. Any building in any reasonably juristiction that has any "real" sized UPS most likely has not only a pre-plan so the FD knows what is where, but also at least annual inspections. Chances are good the facility also has to hold a permit for the number/capacity of the batteries in the unit (per IFC 105.7.2) and most likely the fuel storage for the generators (IFC 105.6.16). Even in your jurisdiction doesn't use that code, IFC and/or it's ancestors provide the model code that most of the US operates on, so chances are high there are similar restrictions/procedures/permitting requirements.
Daryl
If you can stroll into the room and look around etc., sure, why not. I
said that in the previous msg. We agree.
The note I was responding to asserted that it was necessary to hit an
EPO before (direct) firefighting could commence, I wasn't saying it
wouldn't be handy in some circumstances, just "not entirely necessary"
(for firefighting.)
But getting to an EPO could be difficult if the room is closed and
it's looking like it might be somewhere in excess of 450F inside in
which case the usual approach is to smash/open a window or door while
the others stand ready with a fully charged hose. Which is why they'll
usually shut down power from outside the building if needed.
By definition a room on fire is a room out of control*.
An important component of firefighting is working fast as fires don't
usually get better by themselves. Well, actually they almost all do
get better eventually on their own, when there's nothing left to burn,
but that's not often an attractive option since the available fuel
could be what you call your neighborhood.
Also, NOT TO BE TOO LITERAL MINDED, but isn't the point of a UPS that
it has a lot of power even when it's not getting any externally?
Doesn't hitting an EPO on a UPS at best only reduce the electrical
hazard of hitting it with water a little bit?
* Interesting aside: In many venues, I know this is true in Boston,
when a fire official declares a building on fire legal title to that
building is automatically transferred to the fire dept until
firefighting operations are declared ended.
Not an engineer, and not a firefighter, but I think I can answer this
one.
Yes, hitting the EPO would leave a lot of power potential stored in the
batteries in the UPS.
The point of the EPO is to isolate those batteries from both the
external (possibly high voltage) feed coming into the UPS and to isolate
them from the inverters, transformers, power points (plugs) and whatever
else is used in the build-out getting the power out of the batteries and
to the equipment.
This achieves a couple things.
* It potentially removes one of the requirements of combustion
(heat/energy input).
* If the fire is not within/around the UPS itself, the firefighters can
avoid the power that is still in the room.
* Removes the power from the wiring below your raised floor so water
will not come in contact with the power present during normal operation.
I'm sure that there are others out there that could give you even more
reasons, but these are the ones that come to mind immediately.