On Sun, 22 Feb 2009 11:30:21 -0000, John wrote:

"Andy Burns" wrote in message
et...
John wrote:

not sure you are right to use kWh - kW yes, but not kWh

He's right ... 80 watts x 12 hours = 960 watt-hours = 0.96kWh

I agree with you! Absolutely but the previous person said, "12h a day is
near enough 1kWh". It isn't - it is 0.96kWh

Not trying to be pedantic - but it makes a big difference if you start to
cross reference to other information.

Lesson:

1 Kilowatt running for one hour is 1 kilowatt hour.

500 watts running for one hour = 0.5 kilowatt hour.

1 kilowatt running for 30 mins = 0.5 kilowatt hour

&

80 watts x 12 hours = 960 watt-hours = 0.96kWh

There is no point in precision exceeding accuracy: measuring the input to a
SMPSU will be dubious except with special equipment, so 30 min. running in
24h is irrelevant.
--
Peter.
You don't understand Newton's Third Law of Motion?
It's not rocket science, you know.