Right, the situation is I'm changing some faulty 12volt transformers for some downlights in a kitchen. The lighting circuit is not RCD protected. Now, I know that the switch wires are buried in plaster less than 50mm from the surface. Because I've worked on this circuit and have to issue a minor works certificate. Do I HAVE to provide the RCD protection or is it something I note down in the details of departures from BS7671.