I plan to add a socket to the existing ring main for a TV to be positioned on the centre of a wall about 1.6 m above the floor. To connect to an existing outlet it would require a horizontal chase and a vertical chase as shown in the diagram. I propose a box to be sunk at the right angle for the bend in the cable and to indicate the existance of buried cables. Is this within the regs? The wall is solid and a party wall. I propose to cover the cable with a plastic cover before filling. Is this OK too?