In reviewing an engineer's plan he is taking the computer room load at 65%. This is load being added to a stand-by generator. Is the 65% a code mandated factor or he is own factor? The only demand I am aware of is the first 10KVA at 100% and then the remaining at 50%.(I apologize I do not have a code book with me at this time and cannot remember the specific code section).
Computer Room load
- Thread starter bwyllie
- Start date
- Status
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
Re: Computer Room load
I'm not aware of any code section that would allow derating for computer room IT equipment. This normally runs 24/7 and I would think that the actual load should be used. That is unless the engineer knows something we don't- like some equipment will be shut down in emergencies.
I'm not aware of any code section that would allow derating for computer room IT equipment. This normally runs 24/7 and I would think that the actual load should be used. That is unless the engineer knows something we don't- like some equipment will be shut down in emergencies.
Re: Computer Room load
I can't speak for your engineer, but in my designs the generator loads are based on full load capacity of the UPS, battery plants, lighting, and HVAC loads. The data processing and telecom equipment have nothing to do with it. The secret I use is to base the service load on the square footage of the facility.
I can't speak for your engineer, but in my designs the generator loads are based on full load capacity of the UPS, battery plants, lighting, and HVAC loads. The data processing and telecom equipment have nothing to do with it. The secret I use is to base the service load on the square footage of the facility.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Computer Room load
dereckbc,
Your telling everyone of the secret
The problem is getting everyone to agree on the wattage/Ft^2.
I think 30, I think 60, I think 100, we should plan for the future 130, and so on, and so on, and so on, and so on .......
dereckbc,
Your telling everyone of the secret
The problem is getting everyone to agree on the wattage/Ft^2.
I think 30, I think 60, I think 100, we should plan for the future 130, and so on, and so on, and so on, and so on .......
- Location
- Massachusetts
Re: Computer Room load
So what is a "normal" watt per sq ft number?
So what is a "normal" watt per sq ft number?
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Computer Room load
That's my point, there is none.
As the HVAC guys can cool the stuff faster (or think they can), and cool in tighter areas (chilled water coils in the equipment racks someday), the loads will keep going up. We have been averaging designs in the 100-125 watts/FT^2. We get calls to begin work at 200W/ft^2 and higher too!
Just as a reference, some of these jobs are approx 1/2 infrastructure and 1/2 equipment, so as to support the redundancy and reliability required.
That's my point, there is none.
As the HVAC guys can cool the stuff faster (or think they can), and cool in tighter areas (chilled water coils in the equipment racks someday), the loads will keep going up. We have been averaging designs in the 100-125 watts/FT^2. We get calls to begin work at 200W/ft^2 and higher too!
Just as a reference, some of these jobs are approx 1/2 infrastructure and 1/2 equipment, so as to support the redundancy and reliability required.
- Location
- Massachusetts
Re: Computer Room load
I was getting your point Ron
But I figured there must be a number you personally feel works.
200W/ft^2 That just makes me smile.
Someone has to bring all that power into the room.
I was getting your point Ron
But I figured there must be a number you personally feel works.
200W/ft^2 That just makes me smile.
Someone has to bring all that power into the room.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Computer Room load
It's funny depending on the client, they have quite a wish list.
In Telco CO's, they ask us to be @ 35W/ft^2, but I also have found for this particular type of installation for some of the equipment to be in actuallity 15-20W/ft^2 as it is spread across aisles and ramps etc.
It's funny depending on the client, they have quite a wish list.
In Telco CO's, they ask us to be @ 35W/ft^2, but I also have found for this particular type of installation for some of the equipment to be in actuallity 15-20W/ft^2 as it is spread across aisles and ramps etc.
tonyi
Senior Member
Re: Computer Room load
I'd ask ask about the gear going in before picking a W/ft figure out of the hat..
EMC made some expensive mainframe drive arrays using the Seagate Elite series 5.25" drives. These particular drives burn 35W each and there could be a several hundred of them in a unit or group of units.
I'd ask ask about the gear going in before picking a W/ft figure out of the hat..
EMC made some expensive mainframe drive arrays using the Seagate Elite series 5.25" drives. These particular drives burn 35W each and there could be a several hundred of them in a unit or group of units.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Computer Room load
Although a couple years old, and a bit overdone, see the attached article
http://itmanagement.earthweb.com/datbus/article.php/858901
They talk about loads >200W/ft^2, but I have not seen that yet. Although we have some customers loads at 100W+/ft^2.
[ November 09, 2003, 10:30 PM: Message edited by: ron ]
Although a couple years old, and a bit overdone, see the attached article
http://itmanagement.earthweb.com/datbus/article.php/858901
They talk about loads >200W/ft^2, but I have not seen that yet. Although we have some customers loads at 100W+/ft^2.
[ November 09, 2003, 10:30 PM: Message edited by: ron ]
Re: Computer Room load
Ron & Bwyllie, interesting comments. Here is some food for thought.
A typical cell radio site is a 12 x 24 shelter. The load is a 400-amp @ 48 VDC power plant with 125-amps of actual equipment load and 4000 AH batteries, 2-2 ton HVAC units, and 1 KW lighting.
With the lights and HVAC on, DC plant at 125-amps of equipment load, the load current as measured is 85-amps.
What size single-phase service and generator do you think would be a appropiate?
[ November 09, 2003, 11:01 PM: Message edited by: dereckbc ]
Ron & Bwyllie, interesting comments. Here is some food for thought.
A typical cell radio site is a 12 x 24 shelter. The load is a 400-amp @ 48 VDC power plant with 125-amps of actual equipment load and 4000 AH batteries, 2-2 ton HVAC units, and 1 KW lighting.
With the lights and HVAC on, DC plant at 125-amps of equipment load, the load current as measured is 85-amps.
What size single-phase service and generator do you think would be a appropiate?
[ November 09, 2003, 11:01 PM: Message edited by: dereckbc ]
Re: Computer Room load
The measured load does not represent potential operating conditions. If a service loss occurs and the genset does not fire, the site will run on batteries for about two days. When power is restored or the genset repaired, your 400 amp supply will be running 125 amp of equipment and trying to replenish a potential 4000 AH of energy to the batteries. That large of bank could easily absorb several hundred amps of charging current for well over 3 hours. I think the design should include the full rated input to the power supply as well as the other loads (both A/C running continuous)
The measured load does not represent potential operating conditions. If a service loss occurs and the genset does not fire, the site will run on batteries for about two days. When power is restored or the genset repaired, your 400 amp supply will be running 125 amp of equipment and trying to replenish a potential 4000 AH of energy to the batteries. That large of bank could easily absorb several hundred amps of charging current for well over 3 hours. I think the design should include the full rated input to the power supply as well as the other loads (both A/C running continuous)
- Status