Obviously this was a very exciting two days. Saturday and Sunday my sparky friend and his dog came over and helped me connect the kiln to the electrons. I learned a lot, mostly because as I've said before I don't know much about electricty. There he is connecting the 8awg bx that I strung earlier that day to the box. You can see the element tails sticking out through the insulators.
Basically what it comes down to, is that for each pair of the elements, one tail must be connected to another tail from the other element. This is the series connection of the elements. That I understood. I did this after Sparky and the dog left. We'd spent Saturday dealing with cleaning up the sub-panel, and connecting the bx to its breaker.
Come Sunday I had connected all the series connections, and cut the wires for the switch connections. Sparky did the rest.
Here's a shot of the finished wiring, with a multimeter showing the ohms across the top pair of elements. If you go back to the designing the kiln page you'll see that I had asked for 12.8 ohm elements. So the reading should be 25.6. It shows 26.3, that may not sound like a lot, but it is. I've learned enough (see the electric update page) to know immediately that this difference infers a serious reduction in power.
I was pretty worried In fact we had previously measured the elements, each in turn, and they were 13.3 +- 1 with the exception of one which was 13.9. If you do the math (or run my program) you'll learn that that means about 8400 watts. Not good. Nothing to do about it though except send an email to Euclid inquiring about the discrepancy.
Of course, we had to check the resistance for the whole kiln.
So, if one knows the resistance, and the voltage, one can figure out the current...
volts = ohms * amps 240 / 6.9 = 34.7 Now ... that's a serious problem.
amps * volts = watts 34.7 * 240 = 8328 I was pretty pissed off. I presumed that Euclids had messed up.
But, of course, the multi-meter can be used to check amperage. We couldn't do this on the first day, all we could do was check the individual elements. Now that the kiln was wired up, the first thing we did was verify those readings. The 26.3 ohm reading confirmed yesterdays 13.3 ohm element average.
The amperage check showed something completely different though.
That reads 37.3 amps. That means 8952 watts. Much better. So, we ran the ohm meter across what should definitely be a 0 ohm circuit. It showed 0.6 ohms.
So it all made sense. The 0.2 amp drop is likely due to that one element that read as 13.9 ohms.
My kiln is a little underpowered according to the design but by only half a percent.
Of course, we had to turn all the elements to high. We let it sit for a few minutes feeling the warmth while drank some beer. In no time at all the pyrometer showed 80C without the lid on. I became happy.
