i am going to be critical here , one the guy must be italian , as the board looks like spagheti , the cert is half hartedly filled in , missing noughts incorrect Max Zs values and dashes instead of filling in properly ,as has been mentioned no R1R2 readings in my eyes the insulation readings have just been filled in as you have to do an R1R2 test before an insulation test then the Zs to me its the signe of a rushed job ,i wouldnt accept a cert like that sorry moan over
Lenny has correctly pointed out the cooker is on the non RCD side of the board ,also protected by a 40 amp MCB even worse regarding the oven if its been wired into the 30 amp JB over load risk as i pointed out in original thread chances are the oven wire is 1.5mm flex,, the cable looks old as well , the only way realistically the problem can be sorted out on this would be to get the installation tested again inc a pat test of the oven , untill the installation is proved to be clear then every one could guess what the problem may be , this could be a cross connection some where ,there is a good chance the fault lies some where on the ring circuits and its back feeding but as i have said untill all the circuits are tested properly its difficult to asses