I'm of the opinion that all electrical equipment should be protected by RCD.
New heating elements can have a high leakage due to the insulating powder being too damp after the manufacturing process. This is rectified after a couple of hours use as the powder dries out.
Heating elements inherently pose a high risk of high resistance earth faults. Yet our regs here exclude them from RCD protection because of nuisance tripping.
I agree with DJK, these appliances CAN be supplied by RCD. If an element trips an RCD then it should be investigated.
No leakage is good leakage. If its tripping an RCD then it should be disconnected !
