Even the smallest building will benefit from having a garden office electrical menu of eight or ten double sockets, two or three low energy wall lights and an external security light. In a larger office you will may need twelve to sixteen double sockets and four or five low energy wall lights. If this seems a lot, count up the number of electrical items you use in your office. Then add all the phones, cameras, tablets, torches etc that you regularly charge. You will be surprised.

You will also need spare sockets for task lighting. Wall lights provide general lighting but angle poises and table lamps are vital for providing enough light in your work space.