Defy oven element problem persists

My previous problem with a Defy oven element tripping earth leakage was never resolved. The original element that came with the oven had the fault, a replacement element I bought from Defy had the fault, and a third element Defy delivered. No further reaction from Defy.

If I isolate the element from the oven chassis it doesn't trip the leakage. I have taken the element out, connected 230V to heat it up, disconnected and measured a resistance to the sheath sufficient for the 30mA earth leakage to trip. It can only be the Defy elements that are defective.