I have to agree with Lyle, and this is simply because experience should be the teacher, I have no particular problem in an existing installation with two double sockets in reasonable proximity on one spur. Two spurs from one point is certainly not a problem although some still code it C2, and the only reason for this is inadequate knowledge. There is STILL the belief that a 2.5 mm2 cable will melt and catch fire at 28A, and of course this is nonsense, and to cause a dangerous fire starting temperature needs about 75A. Anyone who doesn't believe me should actually try an experiment, as I say experience is the best teacher. If the cables are buried in thermal insulation which is not inflammable (Glass, rockwool etc) then operation at 50A is very unlikely to be dangerous, but foamed polyurethane is much more dubious as proved at Grenfell.

I will ask the question again, because I have never got any yes answers, has anyone ever seen a melted cable on any domestic installation, or even anywhere else, unless an external heat source was involved. I have seen one where a cable was tied to a superheated steam pipe, but even that didn't cause more than a nasty burning smell! I think the warm cable scenario has been grossly over-taught, and this is why it seems to be an issue.

The change from 2 accessories per spur to one in BS7671 was probably not necessary, and cannot have been in any way evidence based, except the usual "what if" argument which I hate. That kind of thing is not engineering, which is risk based in all cases, it is bureaucracy at its worst.

I claim the prize. I can not remember ever seeing any P.V.C. insulated cable heat damaged along its length by overloading. I have seen P.V.C. heat damaged at badly terminated cable ends at accessories though, mainly due to loose termination screws. But even then there was no fire. Most cables are well oversized for their intended use. Even an 8.5kW electric shower run in mini-trunking on a 2.5 T&E cable did not damage the cable.

P.S. An old thread on this forum mentioned melted lighting cables due to diverted neutral currents some time back.

Z.

I claim the prize. I can not remember ever seeing any P.V.C. insulated cable heat damaged along its length by overloading. I have seen P.V.C. heat damaged at badly terminated cable ends at accessories though, mainly due to loose termination screws. But even then there was no fire. Most cables are well oversized for their intended use. Even an 8.5kW electric shower run in mini-trunking on a 2.5 T&E cable did not damage the cable.

P.S. An old thread on this forum mentioned melted lighting cables due to diverted neutral currents some time back.

Z.