House currently has a 7KW shower on a 30A MEM rewirable fuse in the full rate CU. If this is upgraded to a 8.5KW unit the old consumer unit could be renewed to provide a suitable MCB. There is also a modern Total Control split load consumer unit which includes a section for 24 hour equipment such as a focal point fire. Is it acceptable to run the shower off this Total Control supply? This would make the job easier as it would merely need an additional MCB.