electric shower

hi,i'm a worrier so here goes,electric shower in 1980 house new fuse box correct rcd right rating for shower outside bathroom neon light on off switch but found commons where a wee bit loose only got 1cm slack on cables in back box see correct 10 mm cables but as 10 mm cable goes thru wall to triton shower is in sheaving bit too long unit on cable side sits 1 cm proud pushing unit away from shower wall all works fine rcd has safety trip button beneath off/on switch.is this set up safe as its slightly off tiles behind unit all screwed to wall and tight.
regards to you all,cheers

 

thanks Mr Handyandy,thats as clear as a pint of dark stuff !lol !

 

thank you very much some good ideas i will defo cut back the sheathing and resilicone,thanks CGN.

 

many thanks