ping Andrew Gabriel

Thanks Sue. I looked in that thread, but as someone without any particular credibility in uk.legal as I haven't been a regular there for 15 years now, there seemed little point in correcting the majority of posts which claim that just because a light dims when a vacuum cleaner is turned on, there must be something wrong with the wiring. That's what happens when a thread is started in an inappropriate newsgroup. The wiring sounds fine based on what has been posted, and the problem looks to be with the under floor heating, controller probably. When they get their first electric bill after using it, they'll find they can't afford to run it anyway ;-) It's a stupid heating choice for a giant conservatory.

Oh, I think that you underestimate the size of the pool of people that hold your opinions in very high regard!

As to stupid heating choices, I have a big, walk-in, fireplace and a big, walk-in, barn full of wood. It's a stupid heating choice, given the cost of a load of wood and the amount of effort involved, the uneven temperature distribution through the house, global warming, whatever... but still, visitors' eyes light up when they see it. Now't as strange as folk.