I'm sure I saw it in the regs today. Ill have a look tomorrow and give you the reg no. I'm in bed at the mo so I can't be bothered going downstairs!
I don't know if there is a actual reg saying that 300mm from the sink, i know it does say that in the electricians guide to the building regs. but there is a reg that is applicable here and that is reg,
512.2 External influences,
more specifically 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.
But there is a exception i think which is this reg,
512.2.2 If the equipment does not, by its construction, have the characteristics relevant to the external influences of its location, it may nevertheless be used on condition that it is provided with appropriate additional protection in the erection of the installation. Such protection shall not adversely affect the operation of the equipment thus protected.
which says it is ok as long as it has additional protection which i interperate as rcd's so as long as it has a rcd then it would be fine, me personally though i would not put it within 300mm of the sink.