On Tue, 29 May 2007, Mark Hull-Richter wrote: > On 5/29/07, Jim Perrin <jperrin at gmail.com> wrote: >> >> Watts = Volts x Amps. I usually use a sliding scale based on # of >> machines. > > That has to be the stupidest marketing strategy ever devised. Most > people (yeah, me too) know that, but why can't they SAY so instead of > using "VA"?... > This formula is correct for a resistive load; however, it completely ignores the reactive load. The correct formula is: watts = power_factor X volts X amps You consume volt-amps, but can only use for amps. There are various regulations in place regarding the minimum power factor -- decent power supplies have a power factor of better than 90%. Steve Friedman