I originally wanted to duplicate the oven build in the link below which is 6x5x4 (interior dimensions) but have decided to knock that down to 5x4x3 in an attempt to keep the required BTUs down.
So my primary concern is building an oven that I *think* will run on a 30A circuit and then finding out that it won’t. The BTU calculators I’ve seen vary wildly which is not helping my cause. I’ve also noticed that some of them account for “normal” and “good” insulation and the delta between the BTUs required for those is significant. According to one calculator, for a 5x4x3 oven that will need to raise the temp 350 degrees (worst case in the PNW), I’m looking at 11,500 BTUs (3400 W) with “normal” insulation or 6900 BTUs (2000 W) with “good” insulation. This swing seems huge to me. What would be the difference between “normal” and “good” insulation?
Also, what is the max wattage I can get away with on a 30A 220v circuit? Is it really as simple as V x A = W? If so, it looks like 3400W only requires 16A and I'm well within what I have available...does that sound right?