power sizing for some liebert units

[essenz]

I am retro-fitting a small 1600sqft datacenter with one or two Liebert units (480V 3-PH).

Can anyone tell me the realistic power draw of these units when in full operation mode?

I will either be using a 10-ton or 20-ton unit.

Alot of people have been telling my that rule of thumb is 1KW per 1 ton, so a 10-ton Liebert should draw 10KW of power.

If my math is right, a 10-ton Liebert pulling 10KW while in operation, would be pulling approx 12amp per phase.

480V x A x 1.732 = 10KVA, so A = 12

The reason why I bring this up is because I was talking to the buildings electrical contractor about the power feeds to the space, which is 200amp 480V 3-PH. I mentioned a single 10-ton Liebert, and he said he usually wires those as a 60amp 480V circuit - which seemed overly high? 60amp breaker, when your only pulling 12-15amps per phase?! I know there can be startup surges, but 60amp seems really high.

Any thoughts?

[<kjpro]

Yeah, get the manufactures specifications, follow them and quit guessing.

[Bennett Price]

[Tony]

I don&#39;t see why would you ask some thing like that just look up manufacture tag and in most cases you will find they recommendation isn&#39;t that simple or literature that comes with unit. This units almost always have two compressors and they also have heaters depend on model so little extra power doesn&#39;t hurt but less will. Tony

[New Directions In Building Ser]

One of the good things about Liebert is that their tech support people are willing to help you out - Call them. Yes you do need to think along the lines of a COP of between 2.5 & 3.5 so the refrigeration side will be 30%~40% of the equipment load in kWh (not kW so if you want the unit to cycle off or have some redundancy then make it a bit bigger but not too much) then multiply this by 40% for the fan load and add it (this can be kW because they&#39;ll always be running), plus 8kW/unit for the humidifier and whatever the rating of the reheat element.

I can provide a presentation for close control equipment selection for data centre&#39;s - remove the nopam from my address and send a request if you think that would be helpful.