I have posted the following in relation to previous comments regarding metal tables in a kitchen, but Regulation 8 still applies.
Can I bring the 'Electricity at Work Regulations 1989' to your attention. As you are aware these regulations are statutory and it is a criminal offence if you have not taken reasonalbe steps to comply.
Regulation 8 states as follows; "Precautions shall be taken, either by earthing or by other suitable means, to prevent danger arising when any conductor (other than a circuit conductor) which may reasonably foreseeably become charged as a result of either the use of a system, or a fault in a system, becomes so charged; and, for the purposes of ensuring compliance with this regulation, a conductor shall be regarded as earthed when it is connected to the general mass of earth by conductors of sufficient strength and current-carrying capability to discharge electrical energy to earth."
So the metal table which is a conductor must be earthed if a piece of electrical equipment is intended to 'sit' on the table.
Sorry this reply is drawn out but it is important that these regulations are followed in addition to the IEE Regs.