I guess you can't get a high bill from a 3000 watt heater locked on
24/7 then?

After all a 3000 watt heater doesn't glow so it can't produce the

3kW x 24hr. x 30days x $0.10/kWh = $216 extra on your bill.

I guess he meant a $5000 electric bill before you can have a fire.


"Neon John" wrote in message
...
On Thu, 24 Jan 2008 18:54:22 -0900, (Floyd L.
Davidson) wrote:

Neon John wrote:

Really? Then according to your expert theory, my restaurant ought
to have burned
down long ago.

http://www.neon-john.com/images/Wiring_overload.jpg

Sure sonny. Now tell us just how much electricity that
mess actually used. Nothing there used up enough power
to cost more than 20 cents a month!

My, such charm and wit.

OK, well "Pop", let's go back to that Stefan-Boltzmann calculator
and do a little
math.

The conduit between the meter base and that box is about 40 ft of 2"
rigid conduit.
It runs exposed so we don't need to worry about conduction losses,
only radiative and
convective.

Forty feet of 2" conduit is 21 sq ft. Let's use 80 deg C for the
conduit because
that is just about "too hot to touch" and 20 deg ambient. We'll use
0.95 emissivity
since the conduit is old and dirty and pretty close to a black body.
That comes out
to 858 watts. In that temperature range, convective losses will be
about twice those
of radiative losses so we'll figure 1716 watts there for a total of
2,574 watts.

My restaurant was open about 70 hours a week and the load remained
fairly constant
throughout the day so 2,574watts * 70hours * 4weeks = 721kWh. At
$0.09 per kWh,
that's $64.89 per month. A bit more than 20 cents a month, wouldn't
you say? Chop
the calculated amount in half or even by 10 if you like. Doesn't
matter, you're still
wrong by an order of magnitude.

And I didn't even try to account for the cost of air conditioning
that heat to the
outside, a necessary task since all but a couple of feet of the
conduit runs in air
conditioned spaces.

Sanity check: Using the 0.000292 ohms per foot from
http://www.epanorama.net/documents/w...esistance.html for
#4 wire and 120
feet of wire (three phase) and 300 amps, that works out to 3,154
watts. At 250 amps,
2,190 watts. That brackets my calculated values nicely. Sanity
check passes.

Feel free to plug your own numbers and see what you get. It'll be
20 cents.

You remind me of that old saying: "Those who ignore the math are
doomed to look like
idiots."

John

--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com -- best little blog on the net!
Tellico Plains, Occupied TN
Unable to locate Coffee -- Operator Halted!