City & Guilds 2391-51 study plan
City & Guilds 2391-51 · Give each week a clear focus.
8 weeks · About 7 hours per week
Visual inspection of electrical installations and identification of non-compliance and deterioration & Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing
List the statutory and non-statutory documents that govern inspection and testing and state the legal status of each
Identify, from written descriptions of installed equipment, at least 30 examples of non-compliance or deterioration
Match each identified defect to the relevant requirement in BS 7671 or the associated guidance
Distinguish between departures that require improvement and those that are immediately dangerous
Rank identified defects in order of severity without yet assigning classification codes
Your checkpoint
A 30-item visual inspection defect log with a regulation or guidance reference and a severity ranking for every entry
Safe isolation, safety management and safe working practices on site & Dead testing: continuity, ring final circuit, polarity and insulation resistance
Write out, from memory, a full safe isolation procedure including proving the tester before and after use
Justify the selection and inspection requirements for test instruments and leads under the relevant guidance
Perform and record protective conductor continuity and main bonding continuity results on a practice installation
Carry out ring final circuit end-to-end and cross-connected readings and interpret the resulting r1, rn, r2 values
Confirm polarity at every relevant point of a practice circuit and record the outcome
Your checkpoint
A completed dead-test record sheet for continuity, ring final circuit and polarity on a practice board, with calculated expected values alongside measured values
Dead testing: continuity, ring final circuit, polarity and insulation resistance
Select the correct insulation resistance test voltages and minimum acceptable values for different circuit types
Explain how to prepare an installation for insulation resistance testing and which items must be disconnected
Calculate expected insulation resistance values for a given set of parallel circuits
Describe how to interpret an unexpectedly low insulation resistance reading and state the next action
Sequence the full dead testing regime in the correct order and justify that order
Your checkpoint
A written dead-test sequence for a specified installation, including test voltages, expected values, tolerances and the action to take on each unsatisfactory result
Live testing: earth fault loop impedance, prospective fault current, RCD and functional testing
Describe the methods for measuring earth fault loop impedance at the origin and at the furthest point of a circuit
Calculate expected loop impedance values from protective device characteristics and compare them with measured results
Distinguish between prospective fault current measurement and calculation, and state where each is appropriate
Carry out and record the full set of RCD tests, including the half-rated current, tripping time and operating time checks
Justify the functional testing required for a completed installation and list what must be verified
Your checkpoint
A live test results table for a practice installation showing measured and calculated earth fault loop impedance, prospective fault current and all RCD test results, with each result judged as compliant or non-compliant
Milestones
Week 2: Reproduce the safe isolation procedure and the dead-test sequence unaided, scoring at least 80% on a self-marked written check
Week 4: Complete a full set of dead and live test results for one practice installation within a two-hour time limit, with no missing readings
Week 6: Correctly assign observation codes to 20 written scenarios, with a written justification for each code that references the relevant requirement
Week 8: Achieve at least 80% on two timed mixed-topic mock papers covering all eight domains