An interesting problem this.
In NZ and Australia the wiring regs exempt cookers and ranges from requiring RCD protection, and I have always assumed that the reasoning for this is that cooker elements have a naturally high earth leakage current. This makes some sense, as elements constructed with a conductive core and sheath separated by mineral insulation which seems like a good recipe for high leakage.
Can agaricus bisporus advise us is the RCD required by code? If not, then the best bet may well be to remove it.
