I had a wylex consumer unit fitted a month a go and since then every time you turn the cooker on (sometimes) or off (all the time) it trips the RCD. The Electrician put the cooker on the non RCD side it worked for a little while then it started tripping again even though its not on that side. I tried turning off appliances one by one to narrow down the fault but its definately the cooker. To get round using the cooker I turn it off from the wall switch. Whilst checking I watched the RCD trip and saw a spark where the live goes in to it (It is done up tight). Any ideas anyone its driving me crazy.