Hi Folks and belated new year greetings to all. Must be some time since I looked in as there were 18871 headers to download. ;-(
I was under the impression that if wiring is covered by insulation, specifically a ring main under 2" of Celotex or Kingspan plus plasterboard as dry lining on an outside wall, the cable has to be derated but I was chatting to a building acquaintance recently and he said his electrician was using normal 2.5mm wire. Is that according to the regulations? I know there are derating tables but typically have been unable to track anything down on the Internet.