nome wrote:

I did twig that just under 3KW was going to be the limit on a socket
but found some products that still require hardwiring even though less
than 3kw so that confused me

Some suppliers seem to be far too cautious (or careless) when it comes to
supplying this type of information. For example Ikea GAS hobs are described
as "Wired-in installation. Installation to be made by a qualified
electrician." (e.g. http://www.ikea.com/gb/en/catalog/products/70123470) -
just for the fraction of an amp needed for the piezo spark generator, well
within the capacity of a plug and socket. It's probably just standard
boilerplate labelling which they apply to all hobs and ovens without
thinking.

--
Mike Clarke