JD18-JH Electrical Consumption
In February 2008, I was able to get the technician from the energy company to install another inline meter, this time on the JD18-JH electric kiln (for referencing the last meter, see the post: Electric Kiln Actual Energy Consumption).
The meter was set up to record ONLY the electrical consumption of the kiln.
After my 30th firing to ^11-12 and many lower temperature firings, the elements on the kiln look great, and ohm readings from the elements are pretty much the same as when the kiln arrived.
Meter Start Point:
When the meter was installed, it read: 400Kw/h. This will be our “zero point”.
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1st Firing: This image was taken during a crystalline firing, immediately after seeing ^11 achieve a 45° bend.
Reading 1a: 434 - 400 = 34 kw/h used.
Cost (at 9¢ a kw/h): $3.06
… following the ^10.5 peak, there was the crystal soak phase of the firing. This involved ramping up/down and holding between 1900-2000°F (total hold times ≈ 4 hrs).
Reading 1b : 456 - 434 = 22kw/h used for heat-soak.
Cost: $1.98
Reading 1c: 456 - 400 = 56kw/h used for the entire firing.
Cost: $5.04
Summary: The total cost of a ^10.5 crystalline firing, including the 4hr. heat-soak costs about $5.00, and the $2.00 it cost to grow the crystals pretty much does away with the notion that crystalline firings are much more expensive than corresponding firings to the same peak.
This firing was done in the JD18-JH. One of it’s design characteristics is to cool out of the top heatwork zone before the perfect cone bend (and the glaze!) can be altered by residual heatwork. One of the arguments against this design was that it would either have trouble hitting the temp’s I wanted, or it would require so much power that firing would be expensive… obviously, neither is the case.
Following the crystal growing holds (heat-soak), the drop through quartz inversion and below was slow and smooth. When I unloaded the kiln, my witness cones looked nearly identical to what they did when I stopped the kiln’s peak temperature hold and began the descent.
Of course, if I’m going to fire the kiln, I may as well put something in it, yeah? … 
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Second Firing: achieved ^020 @90° bend:
Reading 2: 463 - 456 = 7 kw/h used.
Cost: 63¢
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3rd Firing: Achieved ^05 @90° bend:
Reading 3: 482 - 463 = 19kw/h used.
Cost: $1.71
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4th Firing: Achieved (another) ^020 @90° bend:
Reading 4: 489 - 482 = 7 kw/h used (Compare to 2nd firing: Man, I like seeing repeated accuracy).
Cost: 63¢
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