Today I purchased a new hob and oven, both electric, the oven comes with its own cable with a fitted 13amp plug, the hob comes with the normal electric cooker cable, after installation it says in the instructions to run the oven for an hour before use, I did this without any problems, my wife went to make lunch and after a while when we touch the hop or oven metal parts we get a tingling like shock, can anyone help please..thanks.