# MACPRO electrical draw down question

Discussion in 'Mac Pro' started by emeldahay, Mar 25, 2010.

1. ### emeldahay macrumors member

Joined:
Jul 7, 2007
#1
I`m looking at leasing a office unit with what ive been told has "60 amp 600 volt" electrical capacity.

The unit can be upgraded to 100amp with an additional 45KVA transformer.

at its current 60amp limit how many 8 core MACPROS with 30' apple monitors can I have running at once?

at 100amp limit how many?

Im not sure if air con is powered separately to the main supply. For this calculation Im assuming NOTHING else is using this circuit.

many thanks for opinions!

2. ### djjclark macrumors regular

Joined:
Feb 17, 2008
#2
....edited out assumptions ....

But really if you are going to drop \$60k - \$100k on computers go hire a electrical contractor that knows this stuff.

3. ### emeldahay thread starter macrumors member

Joined:
Jul 7, 2007
#3
I will

but im trying to figure out things today to get a ballpark.

im going to get a meter and get a rating for a system working at full tilt.

4. ### Phantom Gremlin macrumors regular

Joined:
Feb 10, 2010
Location:
Tualatin, Oregon
#4
Don't be confused by the "60 amp 600 volt" stuff. The electric monopoly won't just deliver 600 volts to you and leave you to fend for yourself. Their supplied transformers will step down the voltage for you, thereby increasing the available current by the corresponding ratio.

60 A at 600 V means 300 A at 120 V. I'm far too lazy to look up the specs, but I'd bet that a Mac Pro with monitor will take less than 7 A. So that means you can run 42 systems.

As someone already said, consult an electrical contractor. Your bigger problem will be the branch circuits. You probably won't be able to plug in more than two Mac Pros (three if they're not maxxed out) into a single 15 A branch circuit. And normal buildings aren't wired with a huge number of 120 V branch circuits. They assume that much of the load will be at 240 V or greater. Each room in an office building might only have two different 15 A branch circuits going to it for wall outlets.

And don't forget A/C. Pack a dozen Mac Pros into a room and the standard A/C airflow might be inadequate. In fact the entire building's A/C might be inadequate because it probably isn't designed for supplying massive cooling to one or two rooms.

5. ### nanofrog macrumors G4

Joined:
May 6, 2008
#5
Worst case (max draw of both units added together), 21.

P = voltage * current, so P = 60 * 600 = 36kW

125VAC * 12A = 1500W off the wall for the MP max
150W = rated max draw of 30" ACD

So Max System draw = 1650W

36kW/1650W = 21.8 = 21

However, they're not going to draw that much. Realistically, you might be pulling 450 - 500W (base to modest upgraded equipment internally).

So it should be closer to ~70 systems.

At 600V, 100A, you'd get a realistic system count of ~120 (using max draw per system, then ~36).

But make sure about whether or not the Air Conditioning, lights,... are on that panel.