You can place sockets and switches at any height. The main requirement is the convenience of using these devices. Many experts talk about the European standard. It says that switches should be placed at a distance of 90 cm from the floor, and sockets — 30 cm. In fact, these are fictional standards for ordering consumer requirements. Recommendations for placing sockets in the kitchen and near the desktop are that they should be above the working surface for the first, and above the surface of the table — for the desktop.