Data center - EPO

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bnewport

bnewport

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NEC 645.10 spells out the requirements for an EPO button. The NEC handbook states that the circuits in the IT room must be disconnected from their supply. 645.11 states that if the UPS installed within the IT room, it must also comply. If the UPS is not installed in the IT space, but in an electric room, does it need to be shut down? I believe that in an emergency, such as a fire, the UPS and battery would need to be shut down, since the fire dept will shut down the mains and think that the building is all electrically dead. The IT rooms in question are 2 separate rooms, each fed by shared UPS units. ie: Room 1 is fed from UPS 1 & 2, Room 2 is fed from UPS 2 & 3. If room 2 EPO is pressed, the customer does not want room 1 affected. Since the UPS(s) are installed in the electric room, could individual feed breakers be shunt tripped to disconnect the circuits??? The UPS is not "installed within the IT room" as stated in 645.11. Thanks-
 
Considering the intent of 645:
645 is an optional article that allows more lenient wiring rules in the IT equipment space as compared to the other Chapters of the NEC, and as a result, if you want those rules applied in the IT equipment space, you need to disconnect power to the electronic equipment in that space.

Most of the time, the EPO function is accomplished with shunt trip breakers on the UPS output (considering the UPS is off the IT floor).

My first suggestion, if reliability is important, is ....
Don't use the leniencies found in 645, then an EPO is not required, problem solved!
 
Ron-

Thanks for the quick and knowledgeable reply. I completed a union apprenticeship, took many code classes, passed the Michigan code exam, etc... and no one ever gave the answer you just did. I have built / worked in many data centers, and worked with many IT managers. I dont remember too many data centers that did not have epo buttons. A lot of what I have learned concerning IT spaces was self taught. I always assumed a dedicated IT space had to have an epo, since 99% of them did. IT managers cringe at the thought of one simple button that can cause their whole world to come crashing down. Anyways- let me see if I understand- article 645 is all or nothing. If you want the exceptions that 645 provides (such as having a pdu) you have to comply with the requirements as well, but 645 is not mandatory? I need to read that article a few more times to take it all in. Great article!
Thanks again!
 
bnewport said:
If you want the exceptions that 645 provides (such as having a pdu) you have to comply with the requirements as well, but 645 is not mandatory?
Click to expand...

A PDU can be used anywhere.

The thing thing that using 645 gets you is the ability to use more cables and cords in place of permanent wiring methods.
 
iwire said:
The thing thing that using 645 gets you is the ability to use more cables and cords in place of permanent wiring methods.
Click to expand...


And depending on how often equipment is moved or changed in an IT environment, this can be a huge cost savings down the road. The initial cost could be higher but having salaried Joe Scrub computer geek relocating equipment with cords as opposed to paying for an electrician to come in a 4am on a Sunday morning for double time can save a lot of dough.
 
Bob,
Funny enough, there was just a ruling by the local AHJ's in NYC, that a PDU is a leniency provided by 645, and can be used only in a 645 compliant environment.
No problem for me, be cause I wont call it a PDU, just a static transfer switch, transformers, panelboards, TVSS and some metering put together .... not a PDU. :)
 
Ron I guess I use PDU differently, apparently in a wrong way.

'PDUs' I have installed where typically just a transformer and group of panel boards in one enclosure.

These where supplied by equipment such as transfer switches, UPS etc.
 
Bob,
You're correct too, PDU is not defined.
It could include any or all of the items I listed before, in many different configurations.
That's why I think its goofy that NYC ruled in the way that they did regarding this mysteriously defined item.
 
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