The main oven on my Smeg DUCO8CSS integrated oven trips the RCD after heating up (about 10~15 minutes). The small oven works fine without issue. All the articles I read on the internet pointed towards the fan element being faulty, so I bought a new one and fitted it and.... the problem still exists. I asked an electrician friend to have a look and they used an insulation tester that confirmed that the new fan element was fine, as was the fan motor and the light fitting. So I'm stuck in a quandary now as I don't know what the problem is, so I can't solve it. Does anyone have any ideas as to what it may be and if there are any associated checks I can do to prove it? Any help would be very appreciated.