Hello, Just wondered if there's any methods to extend a cable that feeds the electric shower that can be chased into wall. Current shower cable runs up wall outside bathroom - surface mounted into switch on the outside of bathroom and then from switch runs through to shower. Switch is bellow banister rail and is a surface mounted box which is an eyesaw. Would want to move the switch above banister and surface mounted which would probably involve extending cable a little. What methods can be used to extend a cable supplying a shower that are safely to be buried into a wall. Many thanks