Cable Diversity for Induction Hob

In Germany the usual setup is a 2-phase supply at 16A/phase - which seem to rather neatly match the nameplate 7.35kW.  The Germans don't bother with diversity much as for their system it makes little difference (if we used the UK formula on each phase it would only reduce from 16A to 11.8A). With the UK system 32A single phase reduces to a much more economic 16.6A.


The first 10A plus 30% of the remainder (plus 5A for a socket) rule for stationary cooking appliances goes back to at least the 14th Ed (circa 1966) so has certainly stood the test of time. Even if you consider a separate hob is a little different to a conventional cooker - the difference is only the oven which is typically only around 2kW or less - so I suggest would make little difference to the outcome. (As a thought experiment, add a 2kW oven to the hob - so giving an overall nameplate rating of 9.35kW - after diversity you're still under 20A.)


If you do go for a 32A circuit - be aware that 4mm² is only suitable when clipped direct (or embedded in plaster etc) - when in a building void (e.g. between ceiling and floor above - method B) it's only rated for 30A. 32A/6mm² is a pretty standard arrangement that'll cope with the majority of cooking appliances.


   - Andy.

In Germany the usual setup is a 2-phase supply at 16A/phase - which seem to rather neatly match the nameplate 7.35kW.  The Germans don't bother with diversity much as for their system it makes little difference (if we used the UK formula on each phase it would only reduce from 16A to 11.8A). With the UK system 32A single phase reduces to a much more economic 16.6A.


The first 10A plus 30% of the remainder (plus 5A for a socket) rule for stationary cooking appliances goes back to at least the 14th Ed (circa 1966) so has certainly stood the test of time. Even if you consider a separate hob is a little different to a conventional cooker - the difference is only the oven which is typically only around 2kW or less - so I suggest would make little difference to the outcome. (As a thought experiment, add a 2kW oven to the hob - so giving an overall nameplate rating of 9.35kW - after diversity you're still under 20A.)


If you do go for a 32A circuit - be aware that 4mm² is only suitable when clipped direct (or embedded in plaster etc) - when in a building void (e.g. between ceiling and floor above - method B) it's only rated for 30A. 32A/6mm² is a pretty standard arrangement that'll cope with the majority of cooking appliances.


   - Andy.