I think some of you gents are looking at this too deep I don't want a full design.
I think it's you that's not looking deep enough. There are certain times where we can apply a rule of thumb, like a final lighting circuit. We all know that a circuit serving 10 points and using less than 100m of cable will be fully compliant with current carrying capacity and volts drop requirements using a certain sized cable without having to sit down and do a cable calc.
It doesn't work with the same with submains as every installation is different, as you've already proved.
Would you want to pay for some big numb cable if you are only running a socket and a light, or would you prefer someone to calculate what size cable is really required for the proposed load?
Just suggestion like its normally done like this
It really is done by talking to the client about the proposed useage of the new supply and then calculating cable size from there. Electricians do a lot of cable calcs, so it doesn't take long, but it does make sure everything will actually work, the cable won't overheat and burn your house down, but on the other hand you haven't shelled out for a cable which could power a small country as you couldn't be bothered to work out if a smaller cable would be ok.
....or as a rule of thumb you put a switched fuse on your incomer and an RCD at the end consumer etc etc.
There is no rule of thumb that covers all installations. How could there be?
Every job is different in what is required, as has to be designed accordingly.
For example when they put in the cable to my house as the main supply they didn’t ask any questions about what I was plugging in or how I was doing this or that. They just plopped the cable in and stuck a fuse / meter on the end of it. How I use that supply is then up to me (again keeping within the regs). So a standard answer like the gent gave above like I would expect a 60 amp supply to the accommodation is quite helpful. If you are telling me there isn’t a standard approach to this and I will need to do a complete load analysis before thinking of a supply (even though they use standard installs for new builds).
Yes that's exactly what we're telling you.
When you apply for a new service from the DNO, they ask you how big a supply you require. Just because you didn't do a load calculation, doesn't mean someone else hasn't done it for you.