Hi Mickus, I have moved this to the DIY section and thus not approved your duplicate thread, repeating threads in different forums only leads to confusion for members and staff.
On the note of advice, the regulations are very different from those of the eighties, I know, I did my apprenticeship during them, having said that the basis of calculating cable size remains pretty much the same.
The advice you have been given is more than we would normally give you since you are too far removed from the industry now, I think your honesty and the fact you have a little history in the trade won you a few brownie points.
That aside and noting what has been expressed already, you will need to catch up on requirements to this circuit which should now be looking to meet the 18th edition although I do not think there is much difference to what your are doing from the 17th edition requirements in all honesty but it must be tested out so I suggest a 3rd party to sign it off for you and keep you within regulatory requirements.
May I ask why you packed the trade in?.. the eighties was a good wage and plenty of work out there.