Have just extended an existing ring main in my kitchen to add some new sockets. Have checked an double checked all cabling at sockets, and have checked continuity of the ring between all sockets and also end to en at the CU, but when I power up there is no power to any sockets. Have tried another MCB - same story. have even tried wiring only one socket directly (radially) back to the CU at both ends of the ring but no joy - bit of a mystery to me - can anyone suggest a solution?