Part 3 of BS7671 is a case of ‘just what it says on the tin’.
Think of it as all of the things you would need to consider with regard to designing an electrical installation…
Chapter 31: Purpose, supplies and structure. What’s the installation for ie commercial, industrial or domestic. What’s its structure, circuits – how many and the layout etc. What’s the incoming supply TN-S, TN-C-S or TT?
Chapter 32: Classification of external influences. Are there any environmental considerations you need to take account of.
Chapter 33: Compatability. Are there any items of equipment or parts of the installation that may have a detrimental effect upon other parts of the installation.
Chapter 34: Maintainability. Considerations concerning the lifetime of the installation with regard to the quality of maintenance it can be expected to receive. Important that the protective methods remain effective as well as the proper functioning of equipment.
Chapter 35: Safety services. Are there any safety services, fire alarms etc.
Chapter 36: Continuity of service. Is there anything that you don’t want to go off, pop or bang within the installation ie life support systems.
Just 6 questions on Part 3 in your City and Guilds 2382-12 exam and it covers only 8 pages. Hopefully not too difficult