Off topic slightly but do people treat these things like the bible or just pay lip service to them, I can understand them in a commercial environment where things are critical but every time I've used an on-line cable calculator its way over specced things.
I remember a couple of years ago we were subbying for another spark converting a building into apartments, it was a long and thin building and reminded me of my school. The main contractor was supplying all the materials and me and the spark were just doing the work. they tried to get the spark to spec the cable etc but he said he was just the installer and not the designer and put it all back onto them, he pointed them in the direction of a cable calculator website.
A couple of days later the spec came back and they said the cable size for the furthest away apartments would have to be 120mm, he handed them the paper back and said "try again". As it was the ones furthest away ended up wired in 50mm which I still thought was ludicrous given they were mainly 1 bed apartments with 3 or 4 electric panel radiators in. Even the cleaners socket down the end of the hallway was wired in 6mm T&E, EM lights 2.5 3core&E.