The simplest way to do it is to use a changeover switch with one side on the mains and the other side on a 32A surface mounted plug. Get a portable generator and a lead with one trailing socket outlet and one plug to connect to the generator when needed.
You need to provide an earth rod to comply with BS7671.
[This message has been edited by TeesdaleSparkUK (edited 09-05-2005).]
