from another forum:
The simple answer is that BS 7671 does not specify a minimum distance. However, Regulation 512.2.1 requires due account to be taken of external influences. An extract from the regulation is reproduced below for ease of reference:
Extract from Regulation 512.2.1:
'Equipment shall be of a design appropriate to the situation in which it is to be used or its mode of installation shall take account of the conditions likely to be encountered.'
Domestic kitchens, bedrooms and cloakrooms (unlike bathrooms and shower rooms) are not included amongst the special installations or locations in Part 7 of BS 7671 and are not rooms where the resistance of the body is likely to be significantly reduced. Therefore, normal precautions against electric shock should be adequate and the general rules of BS 7671 are applicable.
However, whilst BS 7671 does not forbid the installation of a socket-outlet or other accessory close to a sink in a domestic kitchen, bedroom or cloakroom, the requirements of Regulation 512.2.1 have to be taken into account.
The requirements of Regulation 512.2.1 mean that ordinary BS 1363 socket-outlets and similar accessories are not suitable to be installed so close to sinks or draining boards that they are likely to be splashed with water or operated with wet hands.
The penetration of water into an accessory could have serious effects. Water entering the terminals and mechanism may lead to corrosion, internal arcing, general degradation and eventually malfunction. Additionally, and more seriously, water may provide a track for the line voltage to be transmitted to the front cover of the accessory, giving rise to the risk of electric shock.
The same would apply for the socket over the cooker, there is no reg (or specific guidance) saying you can't put a socket above a cooker, however there is lots of guidance about the cooker control switch.
Also from the Electrical Safety Council Technical Manual
The means of interrupting the supply on load should be readily accessible but the device should not be positioned where, in order to access it, a person would have to reach over the cooking appliances. Consideration should also be given as to whether the position of the device enables it to remain readily accessible in the event of a cooking fire.