Hi - I am about to replace my old power shower and discovered the following:9.0kW (240V) shower, 6mm² wiring (run length less than 10m), 30A rewirable fuse in consumer unit.
To my mind this should not be possible and should really require 10mm² wiring and a 45A fuse. Just to make sure that nothing was amiss I rewired the fuse and also tried a replacement 30A cartridge fuse - both worked fine.
Just to make things more difficult - my old style consumer unit does not support new style 45A fuse holders. So my simple (ish) shower replacement job has become a much bigger new consumer unit and rewire shower fitting job..... OR am I missing something??? The supposed 9.0kW shower has worked fine for at least 5 years (since I moved in) and probably a few more in use at least twice a day (at a hot setting).
I can possibly accept that a _shortish_ run of 6mm² wiring might survive working at 110% capacity for the infrequent shower use without overheating (much) or too high a voltage drop - but I cannot see how a 37.5A rated device does not appear to trouble the 30A rated fuse.
Can anybody help me understand.