I need to move a socket around a metre lower and therefore need to extend the cable, which is a spur from a socket in the room above. The access from above is very difficult so running a completely new cable would be quite disruptive.
What is the correct way to extend a cable behind plasterboard? I think part P says that all connections have to be 'accesible', but what does that mean exactly. Is it acceptable to use a junction box, if the wall is then plastered over?