OP
dan-in-kingston
As an aide memoire (I can't be cluttering up my mind with calculations, I'm an artist you know!) I bought a copy of this Electrical Installation Calculations: Advanced: For technical certificate and NVQ Level 3: For Technical Certificate and NVQ Level 3 Advanced: Amazon.co.uk: A.J. Watkins, Christopher Kitcher: Books
It has everything you need in it, with usage examples and explanations. I can highly recommend it.
Awesome thanks, just ordered one