hard wire basically means no plug and socket. This is required for items with high earth leakage. It is normally done also with items requiring more than 13 amp but not required 32 and 63 amp plugs and sockets are available but unusually in domestic homes. With an oven I would expect it has more than a 13 amp supply and would need new cables from the oven to the consumer unit. Most ovens have Watts rather than amps so to help you convert amps times amps = Watts so 13 amp = 2990Watts in rough terms 3Kw. The trips have preferred sizes so 16 amp = 3680Watts and 20 amp = 4600Watt with 25 amp being 5750 Watts and 32 amp = 7360Watts.
Up to 20 amp we normally used 2.5mm cable then we use 4mm for 25 amp and 6mm for 32 for a cooker we would normally run 6mm so it could be used for most cookers that are used in Domestic premises.
But you really don't need to know as Part P regulations have stopped the English and Welsh from installing new circuits unless they are qualified so all I have said is really for information only.
The big thing is if it says must then likely to be high earth leakage which means it would have to be tested to ensure everything was A1 or you could get dangerous voltages and even if you live in Scotland I would advise it is fitted by an electrician and you ensure you get all the test certificates from him which in turn means he can't cut corners and really has to test.
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Last edited by TheDoctor5 on Wed Jan 21, 2009 12:08 pm, edited 1 time in total.