645.10 Disconnecting Means for IT Room

[hforney]

645.10 Disconnecting Means.
A means shall be provided to disconnect power to all electronic equipment in the information technology equipment room.

Am I correct? Simply installing a non fusible disconnect just before the UPS feeder conductors enter the UPS does not satisfy this article. In an emergency this disconnect will kill power to the UPS but the UPS will now provide power instead of the feed.

Shouldn't there be a "mushroom" switch located near the exit door that will disconnect the feed to the UPS and also disconnect the load conductors leaving the UPS?

Thanks for any help,
Herb in New Jersey

 

[iwire]

Re: 645.10 Disconnecting Means for IT Room

Yes at least that's how we handle it the EPO (emergency power off) button kills the UPS and the HVAC. Most times the HVAC equipment is set up for this connection as well as the UPS system.

Also the feeder breakers are shunted and this all must be set up so the generator (if there is one) does not try to come on to pick up the load.

Add a inergen fire suppression system and that needs to trigger the EPO system also.

 

[ron]

Re: 645.10 Disconnecting Means for IT Room

Avoid Article 645 if you can.
If you can't, and need the leniencies permitted by 645 that you can't do in the first four chapters of the code, then.....

Article 645.10 explains how to handle the disconnect, but 645.11 explains specifically how the UPS must be shut down. Your mushroom switch will need to shunt trip the battery breaker too. Don't forget about HVAC.

Bob,
Why trip the EPO for "clean agent" release? It MIGHT be a good idea if there was truly a fire present, but many releases are false. It is questionable whether power shutdown during a fire will inhibit the functionality of "clean agent" fire suppression. It would be a shame to shutdown a 24/7 data center for a false trip. Sometimes the thought process for sequence of operation design for a data center does not always consider personnel safety first, if not required by code (sad but true). Same comment applies for pre-action sprinkler release and fire alarm activation.

 

[iwire]

Re: 645.10 Disconnecting Means for IT Room

Originally posted by ron:
Bob,
Why trip the EPO for "clean agent" release? It MIGHT be a good idea if there was truly a fire present, but many releases are false.

A darn good question, but the dozen or so FM 200 system I have installed and the other Data centers I have been involved with do just that.

I do not design any of this I am just the guy that follows the prints that I am given.

One positive note is that most times the EPO trigger from the inergin system is a pressure switch on the outlet of the tanks.

The tanks will not be discharged on one smoke detector trip, two zones have to be tripped before the solenoid to release the tanks is energized.

The other benefit of this is when you want to work or test the panel you can remove the solenoid from the tank and have no fear of discharge or tripping the EPO.

All this aside I hate working near any of this EPO wiring as it can get costly fast.

Bob

 

[hforney]

Re: 645.10 Disconnecting Means for IT Room

Thanks for the responses. I say it time and time again. The more you think you know about the code the less you realize you know. Spending a little bit of time on this forum has always helped me, and proven my comment true.

Thanks again!

 

[ron]

Re: 645.10 Disconnecting Means for IT Room

Bob,
In working almost exclusively with Data Center type projects, I will suggest that EPO's are one of the biggest liabilities to the redundancies of a Data Center.
It doesn't only take an electrician to take out an EPO accidentally during some preventative maintenance activities, a good minded janitor or clerk doesn't think much when trying to save some KWH's for the company when they turn the lights out when they leave the room. Sometimes more than the lights go out, even if you have plastic covers with integral sirens to warn the person prior to them pushing a mushroom shaped (not light switch shaped) button.

 

[iwire]

Re: 645.10 Disconnecting Means for IT Room

Yes our own guys have hit a button before.

Most times we modify a Stopper II cover, normally used for fire alarm pull stations we take the references to Pull for fire off but leave the audible alarm in place.

You must see the same thing I do at the exit doors.

Pull Station to activate the Clean agent release, an "Abort button" for the clean agent, a key switch to deactivate the the system, the EPO button and jammed in there somewhere the light switches.

It surprises me that more accidental shut downs do not occur.

[ October 04, 2003, 09:31 PM: Message edited by: iwire ]

 

[hforney]

Re: 645.10 Disconnecting Means for IT Room

A dumb question, but than again a dumb question is one that is never asked. Why is it so important to kill power to IT equipment in an emergency situation?

 

[roger]

Re: 645.10 Disconnecting Means for IT Room

I'm going to get on this wagon

Originally posted by hforney:
A dumb question, but than again a dumb question is one that is never asked. Why is it so important to kill power to IT equipment in an emergency situation?

and repeat Bob's earlier phrase

"thats a darn good question"


Roger

 

[dereckbc]

Re: 645.10 Disconnecting Means for IT Room

Originally posted by hforney:
A dumb question, but than again a dumb question is one that is never asked. Why is it so important to kill power to IT equipment in an emergency situation?

It is a good question, I like Ron, design data centers and telecommunication facilities. And we do avoid 645 like the plague if at all possible. The reason is simple, false trips cost millions in lost revenue and customer churn. Not to mention that national defense and civil communication information systems flow through these facilities

However there are some markets where the local AHJ demands that 645 be applied for these type of facilities. When we pressed them as to why, their answer was what we expected. These type of facilities have UPS and battery plants that are not de-energized by cutting the service to the building by your local fire department. OK sounds logical.

However most jurisdictions do not demand 645 applications, so are their fire department personnel lives not as valuable as the ones that do demand 645? I do not think so, but rather a lack of full understanding IMO.

 

[hforney]

Re: 645.10 Disconnecting Means for IT Room

One last bit of information I need (I hope <G>). The 60 KVA UPS will be relocated to the 4th floor. The new feeder will come out of a 400 amp main breaker panel with nothing else connected. The panel used to feed Edpacs (A/C units) which were removed. The bus bars can only accomadate a 150 amp breaker. The panel has a 150 spare. The UPS has logged in a maximum load of 48 amps on A phase, 37 on B, and 22 on C. I understand that connecting the new feeder to a 150 CB will not allow the UPS to provide maximun output. Although the specs call for a 225 feeder what harm can be done if I have the design engineer do all wiring for 225amp feeder, but just utilize the existing 150amp CB. If needed at a later date we just upgrade the panel.

 

[ron]

Re: 645.10 Disconnecting Means for IT Room

hforney,
Does the unit have an input transformer? If so, many times the manufacturers recommended breaker size is set to overcome the inrush of the transformer.
If no xfmr, then give the 150A feeder a try. Put giant signs all around the unit explaining the reduction of capacity.

 

[iwire]

Re: 645.10 Disconnecting Means for IT Room

hforney,

I do not see any reason you could not do this, maybe Dereck or Ron would know a reason not to.

As the computers are continuous loads the use of the 150 amp breaker limits you to 120 amps of UPS load (less actually as the UPS draws power too) This is assuming you are feeding the UPS with 208 and not 480.

If you do this I would recommend some signage that indicates that the load on the UPS is not to exceed 120 amps per phase.

I would also look at the UPS instructions and see if the overload alarm threshold can be adjusted down to 120 amps so you would get an alarm if the load is increased beyond 120 amps.

If the alarm starts sounding you will know it is time to change to the 225 amp feeder.

I will ask why if this 400 amp panel has nothing else on it, why not remove the panel and replace it with a 400 amp fusible disconnect switch with 225 amp fuses?

That will prevent someone adding load to this panel, and is a quick and cheap way to provide the full size feeder.

I very rarely see the load decreased, most times the load climbs as more equipment is added but the old stuff remains in place and running even if not used.

JMO, Bob

 

[iwire]

Re: 645.10 Disconnecting Means for IT Room

I have got to compose my posts faster as I now see Ron had responded while I was typing.(and making breakfast for my kids)

[ October 05, 2003, 08:59 AM: Message edited by: iwire ]

 

[dereckbc]

Re: 645.10 Disconnecting Means for IT Room

The problem you will encounter is battery recharge. What kind of voltage are you running to the UPS. I assume 208 3-phase delta.

Assuming your UPS is 90% efficient (rare), 208/delta you are going to trip your 150-amp breaker during battery recharge.

In other words when you do loose power to the UPS for say more than a few minutes, power is restored, the batteries are going to draw every bit of current from the rectifiers that the load is not demanding, and remain in that condition until the batteries are re-charged.

Could use a little more info, like battery reserve time, system voltage and type to give more accurate answer.

 

[hforney]

Re: 645.10 Disconnecting Means for IT Room

My sincere thanks to all who responded to my post, ?645.10 Disconnecting Means?. I have learned something from everyone who posted a response. I honestly think the best thing would be to replace the panel so that a 225 amp CB can be used. The extra dollars spent by my company will possibly keep me out of my boss?s office getting my can reamed out!

Thanks again,
Herb in New Jersey