[vox-tech] [OT] Electrical Engineering Question

[Rod Roark]

I got my first electric bill at the new house; looks too
high.  So I decided to do an experiment.

Outside the house is an electric meter.  It reads KWH
accumulated on 5 dials, and has a horizontal platter that
appears to spin about 100 revolutions per KWH (anyone know
if this is exactly true for a standard meter?).

So I figure that means 10 watt-hours per rev, or 36,000
watt-seconds per rev.

I timed one revolution with most things in the house turned
off.  45 seconds.  Then I turned on a 250W light bulb and
timed it again.  32 seconds.  So:

  36,000 watt-secs / 45 secs =  800 watts
  36,000 watt-secs / 32 secs = 1125 watts

  1125 - 800 = 325 watts -- for a 250W bulb.

How come?  Should I complain to PG&E, or is there some
gotcha that I'm missing?

Thanks,

-- Rod