Tips?
Practical - If you want to cheat there are plenty of centres which will milk you through the practical. This fact is well known to C & G, but as yet no action appears to have been taken. If you go to a centre where the practical element is actually assessed properly, then you'd best be well up to speed.
Exact terminology - this is not so much pedantry as the fact that these exams are externally marked. Using terms such as 'main earth', earth bonding', cross bonding', 'ring main', 'Electricity at Work
Act' and so on, will result in loss of marks - how does the marker know you actually understand, as opposed to you simply having enough words to bluff your way through?
As Sparkybird has intimated (but been too kind to be blunt) this is not an exam electricians are very well prepared for. Many fail through simple illiteracy and innumeracy.
I sit every single 2391 exam [one day I'll pass!] and I can tell you that there
is a formula; it's called the syllabus.
I could give you the answers now to gain a pass mark in Section A for the exam in two week's time without even knowing the questions, because, whilst I don't yet know the questions, I do know what the answers will be. That's how predictable it is.
(No. That would be cheating!)
The problems largely lie in the preparedness of candidates and their ability to understand what is being asked.
Get a copy of 'Exam Success Inspection and Testing 2391-10' and study it thoroughly alongside GN3 and pages 73-93 of the OSG.
http://www.electricaltraining.co.uk/products/books.htm
You should practice describing every test procedure, step by step (use bullet points rather than sentences and simple diagrams wherever possible).
Calculations - these are bankers:
1. You should be able to calculate the overall insulation resistance of circuits measured in parallel.
2. You should be able to work out the resistances of any circuits given size and length of conductors.
3. Given a length of a ring final circuit you should be able to work out the expected values at each stage of the test.
4. You should be able to describe how and demonstrate by calculation how to verify that a circuit meets the earth fault loop impedance requirements.
All of these are [should be] things that a competent electrician does every day, yet a majority fail the exam because they cannot do it. Don't be one of them.