Why choose 120 volts?

Paul Vixie vixie at isc.org
Tue May 26 19:32:54 CDT 2009

Leo Bicknell <bicknell at ufp.org> writes:

> http://www.apcmedia.com/salestools/NRAN-6CN8PK_R0_EN.pdf
> But what you'll find in the paper is that the change allows you to
> re-architect the power plant in a way that saves you money on PDU's,
> transformers, and other stuff.  Thus this makes the most sense to
> consider in a green field deployment.

noting also that "architect" is a noun, i find that on large plants the
cost of copper wire and circuit breakers add up, where sizes (and prices)
are based on ampherage not wattage.  in the old days when a rack needed
6kW, that was 208V 30A (10 gauge wire) or it was two of 120V 30A (also 10
gauge wire).  somewhere near the first hundred or so racks, the price of
the wire and breakers starts to seem high, and very much worth halving.

once in a while some crashcart CRT monitor won't run on anything but 120V
but for $50 NRC it can be replaced with an LCD.  everything else that's
still worth plugging in (that is, having a power/heat cost per performance
better than that of a blow dryer) doesn't care what voltage it lives on.
Paul Vixie

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