Date   : Sat, 11 Mar 2006 01:54:13 -0000
From   : "David Hunt" <dm.hunt@...>
Subject: Re: Them pesky case stickers (was 1MHZ SCSI/ATA board.)

> It's unusual for electrical loads to be purely resistive, so the
> current is rarely exactly in phase with the voltage.  This means that
> just multiplying voltage and current readings doesn't give you true
> wattage; the current is slightly less when the voltage is at its peak,
> and vice-versa. Power factor is a measure of that difference.  Most
> computer equipment is somewhat reactive and has a power factor of about
> 80% - 90%.  However an elctricity meter does measure true wattage -- or
> rather it measures the energy consumption, which is wattage times time.
>  So to work out the current correctly when dividing by voltage, you
> apply the power factor as a correction.

But...

> > As I took the reading from the meter, that's what I paid for, I'm
> > not quite sure about the correlation between what I actually use and
> what I
> > end up paying for.

Does the meter take account of the power factor ?

Like I said, I didn't measure the current and multiply by the voltage, I
just compared two electricity bills over the same period.

Dave ;)