Re: DATACENTER: Cooling and Cost Data for Web Hosting Data Centers

[<grisha@verio.net>]

On Wed, 8 Dec 1999, Dave Siegel wrote:

> > > Wouldn't 100A per rack be a good number? That's what I am using, then
> > > aggregating actual as we grow i.e. I'm not installing full load of
> > > 10 tonners everywhere, just half and adjusting as we fill an average
> > > of 50-80Ksq.f
> > 
> > What?
> > You've _got_ to be kidding.
> > 100A per rack?
> > Short of a small load bank, I don't know how you could do that.
> 
> A Cisco 12012 requires 2 -48VDC 60A circuits.  3 6509's require 6 20A 110VAC, 
> and would fit in a single rack.  Larger routers require even more current.
> 

When you have redundant power supplies, the load is usually shared between
them, but every _single_ supply should be able to handle the whole load,
should it happen to be the only one left when the others fail. So if a
device requires 2 30A circuits, that really means that 30A (not 60A) is
the absolute maximum this device will ever consume. The 30A figure is
there for you to provide the right gauge wire to avoid fires, and from the
fire regulation point of view, you should expect the device to consume all
60 amps.

A 6509's will never ever exceed 20A (or it would be rated higher, lest the
wiring is a fire hazard), and realisitcally speaking, it probably consumes
between 3 and 15 Amps depending on what it has in it.

Grisha