We have had quite a few complaints from householders reporting damaged or burned sockets in new installations.
On investigation the problems are generally traced back to the fact that specialist contractors, fitting wooden floors, had been using heavy compressors in the course of their work. These were generally plugged in, using a plug top where the fuse had been bridged out, and constant load on the socket, near to, or above, its maximum capacity caused damage to the socket.
We have also had numerous complaints of twin sockets where one side would work but the connections to the other side appear to be faulty.
This has been particularly prevalent in some of the cheaper sockets which are now coming on the market.
Contractors, when testing socket circuits, should never assume that the value on both sides of a twin socket will be the same and should measure both.