Or alternatively, the electrician could comply with Section 722 BS7671, which last time I read and tried to understand, I was left with a minor migraine.
I expect the IET's code of practise, has lots of pretty pictures, for us lessor mortals. They are on the second edition now (2015), mind
I expect the IET's code of practise, has lots of pretty pictures, for us lessor mortals. They are on the second edition now (2015), mind