I currently have a very dated electric shower that has just died. I am looking to replace it. The current setup is wired with 6mm Cable back to a 30amp fuse at the consumer unit. There is also a power swich on the wall. I would like to replace it with a 7.5kw Shower, from my own research this should just be a simple swap with the only adjustment being replacing the 30amp fuse with a 40amp. Something that does confuse me is reference to also having a 30ma RCD fitted? any advice would be appreciated.