Hi KISS
Thanks for the URL. I've seen several versions of that calculator in my search and they all seem to produce a similar result. As you say, may raise more questions than it answers - from my point of view particularly related to temperature. As a novice I have learnt to watch out for excessive heat in components caused by overloading but trying to access the temp of a circuit or part of a circuit, especially before it's built, is beyond me and probably in the 'too many other things to consider' box. The other thing is that it is often the case that the thickness of the tracks is not stated in the sales pitch - should I trust the statement when it is stated in chinese or taiwanese - and I would have thought the quality of the copper would have bearing too.
This question has come up because I'm planning a modification to a PSU kit and I've been looking at the kit PCB to see what components can be directly replaced and which will have to be mounted elsewhere and hard wire connected. I realised that although the kit PCB is 2 layers it is much thicker than stripboard and you can see than some of the tracks are much bigger than others.
I think I'm answering my own question really - anything less than a couple of amps can go on a board with strips connections, but greater than that to use appropriate rated wires .. .. will probably get untidy but safe !
Thanks for your help
S