Flush Mounting
Flush mounting involves cutting into the wall, but offers the advantage of not being as exposed to people working outside the wall.
The other advantages to flush mounting are that it is more convenient and looks better than surface mounting.
Also, horizontal cable is more secure and protected when installed inside a wall.
When cutting the wall the hole should be 12 to 18 inches from the floor and should be the same size as your connector box.
Next, twist a wire around in the hole to ensure there are no obstructions.