The only way to figure this out accurately is to have a kilowatt meter installed in the power supply line.
E-22 is the same as E-6. It means one of the thermocouple wires is connected backwards.
Here is how to fix it:
The Dura-Fire kilns are designed to have all power turned off by the Kiln Sitter/Time. These have a two-pole contactor that can only shut off single phase power.