Currently the connection to my electric oven is by 6mm2 twin and earth connected to the oven wire via a 3 way chocolate block ! There is no cooker switch or CCU. Previous house owner did this. I want to upgrade the circuit so that I have a cooker switch and CCU. I can do the upgrade using the existing 6mm squared cable. If I do this will the work be notifiable to building control? All advice appreciated. Steve.