shower wiring

[danyal]

i have recently brought a new house and the previous owner liked a bit of d.i.y,the shower switch a 45amp pull cord burnt out.not sure if this was due to moisture in the switch shorting it out or cable size to small? i have replaced the switch evrything is working fine now,however i believe the wiring is wrong as it is just spured off the rign main in 2.5mm twin & earth,im sure this is to small?.the fuse board is an old cardridge fuseboard and there are no spare ways,how do i upgrade this wiring?..

many thanks

 

[Spark123]

It sounds like a nightmare!
What sort of shower - is it just a pump or an electrically heated shower?
If it is the latter then is should be on its own circuit - it is probably easier for you to employ an electrician to sort it out if this is the case.