wrote:
In misc.consumers.frugal-living Jeff wrote:

Now, I would say that most stoves use more energy on than off(there's
wide range here, I'm sure my old Jennaire uses no power when off).

Well, sure, like my toaster. It doesn't use any current when it's
not being used.

I don't know how much power a typical stove with electronic controls
uses but I found this.

http://michaelbluejay.com/electricity/transformers.html

After all, I knew that the
oven uses about 1000 watts while the clock uses five.

I think he is seriously over estimating the power usage of a
clock chip and LCD display. 1 Watt would be more like it.
5 Watts would be about right for an old mechanical stove clock.

You are, of course, neglecting the power supply losses. Non switching
regulators typically throw away half or more of the power. The trend is
away from them.


How much energy the clock uses in a day: 5 (watts) x 24 (hours) =
120 (watt-hours)

Now divide that by 5 to get a more realistic value . . .

How long it takes the microwave to the same amount of energy:
120 watt-hours / 1000 watts = 0.12 hours, or 7.2 minutes

This means that if you use a typical microwave oven for less than 7.2
minutes/day, the clock uses more electricity than the oven. Wow.

I probably use my microwave in the 5 to 10 minutes per day range.

That sounds perhaps even low to me and it is possible it uses twice
the power while off. I suppose I could dig out my amprobe and check my
late model name brand microwave since I don't have a kill a watt meter.

In other words, he didn't want to test to find out his "estimate" was
bogus. He probably knew it was high.

Oh blah blah blah.

For my late model GE smallish microwave, it uses 3 watts on idle. That
required winding 30 turns on an amprobe, measuring the current and
dividing by 30 and then multiplying by the line voltage. If you had the
same MW and used it 5 minutes the phantom energy is equal to the in use
energy.

What does yours use?

I have never recommended removing clocks from anything, quite the
contrary. But just because they are necessary does not mean they aren't
trivial. Considering that a microwave is a high drain device while in
operation just shows the depth of the problem for all the low drain
devices that probably have higher idle drain. The old cable boxes
certainly spring to mind. So does anything run by a wall wart.

I have no problem in believing that at least 5% of the energy used in
this country is phantom losses. Probably half of that is recoverable by
better design. With the cost of copper what it is, I'd think wall warts
have a limited future.

Jeff


Bill Ranck
Blacksburg, Va.