AM2 / AM2S common mistakes
AM2 / AM2S · Understand the traps and how to avoid them.
Presents a risk assessment copied from a generic template that does not name the actual hazards of the task in front of them (e.g. no mention of the loft access, the adjacent live distribution board, the asbestos-containing board, or the borrowed neutral on the lighting circuit), and cannot say who checked it or what changed after the site walk-round.
Risk assessment is treated as paperwork to be produced for the assessor rather than a working document, and candidates rehearse it as a form-filling exercise instead of applying it to the job.
What to do instead
Write the assessment from the job itself: for every hazard named, state the control actually used and who verifies it, then re-read it before each stage of the task (before isolation, before installation, before testing) and record any change in conditions.
Leaves over-stripped conductors with bare copper visible outside the terminal, nicked or cut strands, no ferrules on fine-stranded conductors, and does not check terminal torque with a torque screwdriver, moving straight to the next accessory once the conductor is 'in'.
Working against the clock on the composite installation, using borrowed or unfamiliar tools, and judging a termination by feel rather than by measurement or inspection.
What to do instead
Adopt a fixed termination routine per conductor (strip to the gauge mark, insert fully, torque to the manufacturer's figure with a torque driver, tug-test and visually inspect), and repeat it at every terminal including the consumer unit, before moving on.
Deviates from the supplied drawing or specification - changes accessory positions or mounting heights, substitutes a different accessory type, or routes cable outside the permitted safe zones or without the required mechanical protection - and does not tell the assessor.
The candidate works from memory of how they usually do it on site, or improvises when a dimension does not suit the structure, and assumes a small change will not matter.
What to do instead
Read the drawing and mark out all positions and heights before fixing anything; if a genuine obstruction forces a change, stop and confirm it with the assessor first, and follow the safe zone and protection requirements of BS 7671 for the revised route.
Carries out the insulation resistance test with the main switch closed, or with equipment, indicator neons or an SPD still connected, gets a low reading, and either records it as a failure or repeats the test until a pass appears.
The dead-test sequence has been learned as a list of tests rather than as a method, and the candidate does not consider what is still connected across the conductors being tested.
What to do instead
Prove dead and isolate, open the main switch, remove links, disconnect or isolate sensitive equipment and the SPD, then test L-E, N-E and L-N separately at 500 V DC; record the actual value and note on the schedule anything that was disconnected for the test.
Leaves the schedule of test results until the end of the assessment and then fills it in from memory or from scrap notes, producing missing, rounded or invented values, blank boxes, or a schedule that does not match the installation as it stands.
Certification is seen as an admin task to be done after the practical work, and the candidate believes the figures will be remembered or can be reconstructed from the instrument's last reading.
What to do instead
Complete the schedule of test results circuit by circuit on site as each test is finished, in ink, with the actual measured value and the instrument used, so the certificate is built up alongside the testing rather than after it.
Uses the voltage indicator on the circuit and accepts a reading of zero as proof of isolation, without first proving the indicator on a known source and without re-proving it on that source immediately after the test.
The proving unit is seen as an optional extra and self-test on the indicator is mistaken for proof that the instrument and leads are functioning; domestic habits carry over into the assessment.
What to do instead
Perform prove-test-prove as one continuous routine - prove on the proving unit, test at the point of work on every conductor, re-prove on the proving unit - and keep the proving unit in hand until the re-prove is done so the sequence cannot be broken.
Fits a lock-off device but keeps the key in a pocket while others are still working, uses a shared or duplicate key, or applies the padlock and walks away without a caution notice and without re-testing for dead at the point of work.
Isolation is treated as switching off and locking the device rather than as a controlled procedure, and the candidate does not expect anyone else to be on the job.
What to do instead
Apply the lock with a unique key that stays in the candidate's possession, fit a caution notice at the device, and prove the circuit dead at the point of work after locking off - stating each step aloud so the sequence is verifiable.
Isolates the obvious supply and proves dead only between line and neutral, missing other sources - a second consumer unit, a two-way or borrowed neutral on the lighting circuit, a three-phase board, an immersion heater supply, PV or battery storage - and does not test every conductor to earth.
The candidate reads the circuit from the front of the board without checking the installation schematic, and equates 'the lights went out' with 'the circuit is dead'.
What to do instead
Identify all sources of supply from the schematic and a physical trace before isolating, then prove dead on every conductor - line, neutral and protective - to earth and between each other at the point of work.
On finding a fault, starts swapping components - replacing the MCB, the RCD or the accessory - or energises to 'see what happens' instead of proving where the fault lies, and once the fault is cleared does not repeat the insulation resistance, continuity and RCD tests or update the certificate.
Component swapping is faster and more familiar than systematic testing, and the candidate treats the repair as the end of the job rather than the start of the re-verification.
What to do instead
Work a fixed sequence: confirm and record the symptoms, safely isolate, divide the circuit and use continuity, resistance and insulation resistance tests to prove which section is faulty, repair, then repeat the full set of relevant tests and amend the schedule before re-energising.
Gives answers based on habit rather than regulation - cannot state why a 30 mA RCD is needed for socket outlets, cannot size a main protective bonding conductor or say when a circuit is notifiable - and responds to 'why did you do that?' with 'that's how I was taught'.
Knowledge has been learned by rote as procedures without the underlying requirements, so it falls apart as soon as the question is phrased differently or a figure is needed.
What to do instead
For each common decision, rehearse the answer as regulation number plus requirement plus the value or condition (e.g. bonding size from the supply neutral conductor, RCD requirements, notification under Building Regulations), and practise answering 'why' for every step of the practical task.