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AM2 / AM2S practice questions

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Question 1Safe Isolation and Risk Assessment

Before carrying out maintenance on a final circuit in an occupied building, what should be established first?

  1. The circuit identity and permission to isolate Correct answer.
  2. The age of the consumer unit enclosure and its labels
  3. The number of socket outlets that the circuit supplies
  4. The colour of the circuit protective conductor in the board

Explanation

Safe isolation begins with identifying the circuit to be worked on and agreeing the isolation with the person responsible for the installation. Without this, the wrong circuit could be isolated or the supply restored unexpectedly.

Question 2Safe Isolation and Risk Assessment

Which instrument is suitable for confirming that a conductor is dead before work begins?

  1. A non-contact voltage pen used on its own
  2. A two-pole voltage indicator complying with GS38 Correct answer.
  3. A domestic neon screwdriver
  4. A clamp meter set to amps

Explanation

A two-pole voltage indicator to GS38, proved on a known source before and after use, is the accepted means of proving dead. It applies a load across the conductors and gives a reliable indication between two points.

Question 3Safe Isolation and Risk Assessment

Why should a padlock and warning tag be fitted to an isolation device during safe isolation?

  1. To reduce the current rating of the device
  2. To show that the device has been inspected that year
  3. To improve the IP rating of the enclosure
  4. To prevent another person re-energising the device Correct answer.

Explanation

Locking off with a personal padlock and tag prevents others from restoring the supply while work is in progress. The key should remain under the control of the person carrying out the work.

Question 4Safe Isolation and Risk Assessment

Immediately before and after testing a circuit for dead, a voltage indicator should be proved on...

  1. a nearby earthed metalwork
  2. a known voltage source or proving unit Correct answer.
  3. the circuit protective conductor
  4. the incoming live terminal

Explanation

Proving the indicator on a known source before and after the test confirms that it was working at the time of the test. This guards against a faulty indicator giving a false dead reading.

Question 5Safe Isolation and Risk Assessment

Why is a neon screwdriver unsuitable as the sole means of proving a circuit dead?

  1. It is not insulated against water ingress
  2. It is too expensive for general use
  3. It may give a false indication Correct answer.
  4. It cannot be used on 230 V circuits

Explanation

A neon screwdriver depends on a path through the user to earth and cannot prove all conductors dead. It can indicate live when dead or dead when live, so it is not an approved proving device.

Question 6Safe Isolation and Risk Assessment

In risk assessment, a hazard is best described as...

  1. The likelihood that an accident will happen
  2. A control measure that removes danger
  3. Anything with the potential to cause harm Correct answer.
  4. The severity of an injury that has already occurred

Explanation

A hazard is a source or situation with the potential to cause harm, such as live parts or a worn cable. Risk is the likelihood and severity of harm arising from that hazard.

Question 7Safe Isolation and Risk Assessment

In risk assessment, risk is best described as...

  1. The cost of implementing control measures
  2. Likelihood and severity of harm from a hazard Correct answer.
  3. The legal requirement to report an accident
  4. Any source of potential harm in the workplace

Explanation

Risk combines how likely it is that a hazard will cause harm with how serious that harm could be. Control measures are chosen to reduce this risk to an acceptable level.

Question 8Safe Isolation and Risk Assessment

In the hierarchy of control, personal protective equipment is regarded as...

  1. The first control to be applied
  2. A substitute for a safe system of work
  3. The last line of defence Correct answer.
  4. A method of eliminating the hazard

Explanation

PPE protects only the person wearing it and relies on correct selection, fit and use. It is therefore the last line of defence after elimination, substitution and engineering controls.

Question 9Safe Isolation and Risk Assessment

What is the maximum permitted exposed metal length at the tip of a test probe to GS38?

  1. 20 mm
  2. 40 mm
  3. 4 mm Correct answer.
  4. 10 mm

Explanation

GS38 requires exposed probe tips of no more than 4 mm, with finger guards and fused leads. This reduces the chance of short circuits and accidental contact with live parts.

Question 10Safe Isolation and Risk Assessment

Which sequence correctly applies safe isolation of a single final circuit?

  1. Identify, isolate, lock off, prove dead Correct answer.
  2. Isolate, prove dead, identify the circuit, lock off
  3. Lock off, prove dead, identify the circuit, isolate
  4. Prove dead, isolate, lock off, identify the circuit

Explanation

The circuit must first be identified, then isolated and secured before it is proved dead at the point of work. Warning notices and re-proving follow before work starts.

Question 11Safe Isolation and Risk Assessment

Before isolating a distribution board that is supplied by both the mains and a standby generator with automatic changeover, what must be done?

  1. Rely on the changeover contactor to prevent backfeed
  2. Switch off the generator and leave the mains connected
  3. Isolate all sources, including the generator Correct answer.
  4. Isolate only the mains supply at the main switch

Explanation

Every source of supply must be identified and isolated because a changeover contactor can fail or be bypassed. The generator and mains must both be locked off and proved dead.

Question 12Safe Isolation and Risk Assessment

A voltage indicator fails to indicate when tested on a proving unit. What is the correct action?

  1. Stop work and obtain a proven replacement Correct answer.
  2. Proceed because the proving unit may be flat
  3. Use the indicator only on earthed metalwork
  4. Tap the indicator to restore the display

Explanation

If the indicator cannot be proved on a known source, its indication cannot be trusted. Work must stop until a replacement indicator has been proved and the dead test can be carried out properly.

Question 13Safe Isolation and Risk Assessment

What is the purpose of a 'Do not switch on - men working' notice attached to an isolation point?

  1. To identify the person who owns the building
  2. To warn others not to re-energise the equipment Correct answer.
  3. To show that the circuit is protected by an RCD
  4. To record the date of the last inspection

Explanation

The warning notice reinforces the lock-off by telling others that the equipment must not be re-energised. It should name the person responsible and be removed only by that person.

Question 14Safe Isolation and Risk Assessment

Live working on a low-voltage installation should be carried out only when...

  1. The circuit is protected by a 30 mA RCD and an MCB
  2. The client asks for the work to be done without interrupting the supply
  3. The electrician is experienced and working alone at the time
  4. Working dead is unreasonable and a permit is in place Correct answer.

Explanation

Live work is justified only where it is unreasonable to work dead, and then only under a suitable risk assessment and permit. Additional precautions such as insulated tools and PPE are also required.

Question 15Safe Isolation and Risk Assessment

When proving a three-phase distribution board dead, which tests are required?

  1. Line to earth on one phase, because the phases are linked
  2. Each line to neutral and earth, and between all lines Correct answer.
  3. Line to neutral on each phase, with the main switch confirmed open
  4. Neutral to earth at the furthest point of the circuit

Explanation

All combinations must be tested: each line to neutral, each line to earth, and line to line. This proves that no phase or neutral remains live and that all poles are isolated.

Question 16Safe Isolation and Risk Assessment

Before working on equipment that contains large capacitors, what should be done after isolation?

  1. Apply a low voltage to discharge them quickly
  2. Discharge the capacitors and prove dead Correct answer.
  3. Assume the capacitors have discharged through the bleeder resistors
  4. Short the capacitor terminals together with a screwdriver

Explanation

Capacitors can retain a dangerous charge after the supply is isolated. They must be discharged using an approved method and then proved dead before work begins.

Question 17Safe Isolation and Risk Assessment

An isolation device has no facility for a padlock. What is an acceptable action?

  1. Switch off the circuit breaker upstream and leave it
  2. Tape over the switch and rely on the warning notice
  3. Ask a colleague to stand by the switch
  4. Fit a lock-off device and secure the key Correct answer.

Explanation

A proprietary lock-off device can be fitted to many switches and breakers that lack a built-in locking point. The key must then be kept under the control of the person working.

Question 18Safe Isolation and Risk Assessment

In the hierarchy of control, which measure should be considered first?

  1. Writing a method statement
  2. Eliminating the hazard Correct answer.
  3. Displaying warning signs
  4. Providing personal protective equipment

Explanation

Elimination removes the hazard completely and is the most effective control. Only when elimination is not possible should substitution, engineering controls, administrative controls and PPE be considered.

Question 19Safe Isolation and Risk Assessment

When should a risk assessment be reviewed?

  1. Only when a new employee joins the company
  2. Before work and when conditions change Correct answer.
  3. Only after an accident has occurred
  4. Only at the annual company audit

Explanation

A risk assessment must be suitable and sufficient for the work and kept up to date. It should be reviewed before work starts and whenever the conditions, method or personnel change.

Question 20Safe Isolation and Risk Assessment

Under safe isolation arrangements, electrical work should be carried out only by...

  1. Anyone who has watched the task being done before
  2. A competent person or supervised trainee Correct answer.
  3. A person holding a current CSCS card
  4. The person who ordered the materials

Explanation

Work must be done by someone competent for the task, or by a trainee under competent supervision. Competence includes knowledge, training and experience, not just a card or familiarity.

Question 21Safe Isolation and Risk Assessment

While isolating a lighting circuit in a house, you find that the neutral is shared with an adjacent circuit. What is the correct action?

  1. Isolate the lighting circuit only and treat the neutral as dead
  2. Work on the circuit with insulated gloves only
  3. Isolate both circuits and prove them dead Correct answer.
  4. Disconnect the shared neutral and leave the other circuit live

Explanation

A borrowed neutral can remain live even when the lighting circuit is isolated. Both circuits must be isolated, locked off and proved dead before work proceeds.

Question 22Safe Isolation and Risk Assessment

When choosing a voltage indicator for use at the origin of a low-voltage installation, which rating is appropriate?

  1. CAT IV, for high transient overvoltages at the origin Correct answer.
  2. Any category, provided the tester is GS38 compliant
  3. CAT I, because the tester is used indoors only
  4. CAT II, because the supply is only 230 V and the tester is hand-held

Explanation

The origin of an installation is a CAT IV location because transient overvoltages are highest there. The voltage indicator must have a category rating suitable for the point of use.

Question 23Safe Isolation and Risk Assessment

When isolating a grid-connected PV installation for maintenance, which isolation points must be considered?

  1. The main switch only, because the inverter is self-isolating
  2. Both AC and DC sides, as the array stays live in daylight Correct answer.
  3. The DC isolator only, because the AC side is dead at night
  4. The AC isolator only, because the inverter stops exporting

Explanation

A PV array generates whenever it is exposed to light, so the DC side can remain live after the AC side is isolated. Both AC and DC isolators must be operated, locked off and proved dead where required.

Question 24Safe Isolation and Risk Assessment

After isolating a circuit, why should the prove-dead test be made at the point of work rather than only at the distribution board?

  1. It confirms the conductors at the work point are dead Correct answer.
  2. It is quicker than testing at the board
  3. It avoids the need for a proving unit
  4. It confirms the circuit protective conductor is connected

Explanation

Testing at the point of work confirms that the actual conductors to be touched are dead. Testing only at the board can miss wiring errors, shared neutrals or backfeeds.

Question 25Safe Isolation and Risk Assessment

A socket circuit in a workshop is isolated at the board, but a voltage is still present at one outlet. Which is the most likely explanation?

  1. The socket outlet is a switched type
  2. The circuit protective conductor is disconnected
  3. The outlet is being back-fed from another source Correct answer.
  4. The voltage indicator is automatically calibrated

Explanation

A voltage at an outlet after isolation suggests a second supply, such as a generator, another circuit or a backfeed. The source must be identified and isolated before work continues.

Question 26Safe Isolation and Risk Assessment

In the context of electrical work, what does 'isolation' mean?

  1. Separation from all sources of energy, secured against reconnection Correct answer.
  2. Unplugging the appliances so that no current can flow
  3. Switching the circuit off at the nearest local switch
  4. Placing a warning notice on the consumer unit door

Explanation

Isolation means the circuit or equipment is disconnected from every source of electrical energy and the means of disconnection is secured so that it cannot be reconnected by anyone else. Simply switching off, unplugging appliances or putting up a notice does not achieve this.

Question 27Safe Isolation and Risk Assessment

Who is responsible for proving a circuit dead before work begins on it?

  1. The client or occupier of the premises
  2. The person who is going to carry out the work Correct answer.
  3. The distribution network operator
  4. The supervisor who issued the permit

Explanation

The person who will physically work on the circuit must personally prove it dead at the point of work, because they are the one who will be exposed to the risk. Responsibility cannot be delegated to someone who is not going to be at the point of work.

Question 28Safe Isolation and Risk Assessment

What is a permit to work?

  1. A certificate confirming that the finished installation complies with BS 7671
  2. A list of the tools and test equipment needed for the job
  3. A quotation for the cost of the proposed isolation work
  4. A written authority to do defined work under set precautions Correct answer.

Explanation

A permit to work is a formal document that authorises specific work under stated conditions and records that the necessary isolations and precautions are in place. It is used where the risks are such that a simple instruction is not enough, such as high-voltage or multi-source systems.

Question 29Safe Isolation and Risk Assessment

Why should the main switch be opened as well as the circuit MCB before working in a consumer unit?

  1. The main switch gives a visible break in the line conductor only
  2. The main switch provides extra earth fault protection to the installer
  3. A single-pole MCB may leave the neutral connected to the circuit Correct answer.
  4. The main switch lowers the prospective fault current at the terminals

Explanation

A single-pole MCB breaks only the line conductor, so the neutral of the circuit remains connected to the supply. Opening a double-pole main switch disconnects both line and neutral and so gives proper isolation of the circuit.

Question 30Safe Isolation and Risk Assessment

Why is a voltage indicator proved on a proving unit both before and after the prove-dead test?

  1. To check that the battery is fully charged for the next test
  2. To confirm the circuit is dead before it is touched
  3. To discharge any stored energy inside the instrument
  4. To confirm it is working and will detect the voltage present Correct answer.

Explanation

Proving before the test shows the indicator is functioning and able to detect the voltage concerned; proving again afterwards shows it was not damaged or faulty during the test itself. Both checks are needed before the circuit can be relied on as dead.

Question 31Safe Isolation and Risk Assessment

A colleague is gripping a live conductor and cannot let go. What should you do first?

  1. Pull them clear by the collar of their shirt
  2. Switch off the supply at the isolation point Correct answer.
  3. Shout at them to jump clear of the conductor
  4. Spray the conductor with a CO2 extinguisher

Explanation

The supply must be isolated before anyone touches the casualty, otherwise the rescuer also becomes part of the circuit. Only once the supply is off should first aid and emergency help be arranged.

Question 32Safe Isolation and Risk Assessment

Which document sets out the sequence of operations and the control measures for a particular job?

  1. The risk assessment
  2. The method statement Correct answer.
  3. The minor works certificate
  4. The BS 7671 model certificate forms

Explanation

The method statement describes how the job will be carried out, in what order, and with which controls in place. The risk assessment identifies the hazards and the measures needed, but it does not set out the working sequence.

Question 33Safe Isolation and Risk Assessment

A risk assessment shows that, even with the controls proposed, the residual risk would still be high. What should happen?

  1. The work can go ahead if the client signs a disclaimer
  2. The work can go ahead provided PPE is issued to everyone
  3. The work must not start until further controls reduce the risk Correct answer.
  4. The work must be abandoned and the installation rewired

Explanation

Work should only proceed when the residual risk has been reduced to a tolerable level, so further control measures must be applied first. Accepting a high residual risk, or relying on PPE alone, does not satisfy the hierarchy of control.

Question 34Safe Isolation and Risk Assessment

After isolation, a two-pole voltage indicator reads 0 V between line and neutral at a socket, but 230 V between line and earth. What does this show?

  1. The indicator is faulty because the two readings disagree
  2. The circuit is dead and the reading is caused by induced voltage
  3. The line conductor is still live, so the isolation is incomplete Correct answer.
  4. The socket is safe because the line-to-neutral reading is zero

Explanation

A live line with an open or disconnected neutral gives 0 V between line and neutral because there is no potential difference across the indicator, yet 230 V still appears between line and earth. The line is therefore still energised and the circuit has not been properly isolated.

Question 35Composite Installation

Before work begins on an isolated final circuit, which procedure correctly proves the circuit dead?

  1. Prove the indicator on a known source, test the isolated conductors and record the result without a second proving check.
  2. Prove the voltage indicator on a known live source, test the isolated conductors, then prove the indicator again on the known source. Correct answer.
  3. Test the isolated conductors first, then prove the indicator on a known source, then test the conductors a second time.
  4. Test the isolated conductors with a multimeter set to resistance, then prove the indicator on a known source.

Explanation

The tester must be proved before and after the test so that a tester which has failed during use cannot give a false dead reading. Testing the circuit comes between the two proving checks. A resistance range on a multimeter is not a safe way to prove dead.

Question 36Composite Installation

A ring final circuit is protected by a 32 A device. How many socket outlets may be supplied from a single unfused spur?

  1. Two twin socket outlets
  2. Three single socket outlets
  3. One single or one twin socket outlet Correct answer.
  4. Any number, provided the total connected load does not exceed 32 A

Explanation

An unfused spur from a ring final circuit may supply only one single or one twin socket outlet, or one fused connection unit. The current-carrying capacity of the spur cable is not adequate for a heavier load. Further outlets require a fused spur or an extension of the ring itself.

Question 37Composite Installation

What is the minimum cross-sectional area of copper main protective bonding conductor for a TN-C-S supply with 25 mm² meter tails?

  1. 4 mm²
  2. 16 mm²
  3. 10 mm² Correct answer.
  4. 6 mm²

Explanation

For a TN-C-S (PME) supply the main protective bonding conductor must be at least 10 mm² copper. The tabulated value is 10 mm² where the supply neutral is 35 mm² or less. A smaller conductor would not withstand the prospective fault current of the combined neutral and earth conductor.

Question 38Composite Installation

What is the minimum degree of protection (IP rating) required for equipment installed in zone 2 of a bathroom?

  1. IPX6
  2. IPX0
  3. IPX4 Correct answer.
  4. IPX2

Explanation

Equipment in zones 1 and 2 of a location containing a bath or shower must be at least IPX4. Where water jets are likely to be used for cleaning, IPX5 is required. Equipment outside the zones is not subject to this particular requirement.

Question 39Composite Installation

A PVC-insulated cable is buried 30 mm deep in a plastered wall and has no RCD protection or earthed metallic covering. Where may it be run?

  1. Within 150 mm of the corner formed by two walls Correct answer.
  2. Across the middle of the wall at any position
  3. Diagonally between two accessories
  4. Within 300 mm of the ceiling

Explanation

Cables concealed at a depth of 50 mm or less must be run in a prescribed zone, such as within 150 mm of a corner, within 150 mm of the ceiling, or in line with an accessory. Diagonal runs are specifically excluded. Runs outside these zones require an alternative form of protection such as a 30 mA RCD.

Question 40Composite Installation

Which cable is required between two two-way switches forming a two-way lighting circuit?

  1. 2-core and earth
  2. 5-core and earth
  3. 3-core and earth Correct answer.
  4. 4-core and earth

Explanation

Two strapping conductors plus a common conductor are needed between the switches, together with a circuit protective conductor. That gives three cores plus earth. Two cores would leave no strapper pair, and four or five cores are unnecessary.

Question 41Composite Installation

Which single device provides overload protection, short-circuit protection and 30 mA earth fault protection for one final circuit?

  1. An RCBO Correct answer.
  2. A type B MCB
  3. An isolator
  4. A 100 mA RCD

Explanation

An RCBO combines a miniature circuit breaker with a residual current device in one module. It therefore gives overcurrent and 30 mA earth leakage protection to the circuit it feeds. An MCB gives no earth leakage protection and a 100 mA RCD is neither 30 mA nor an overcurrent device.

Question 42Composite Installation

Steel wire armour is to serve as the circuit protective conductor of an SWA cable feeding an outbuilding. What must be done at each termination?

  1. The armour must be bonded to the neutral conductor at the origin of the installation.
  2. The armour must be glanded securely and connected to the earthing terminal of the enclosure. Correct answer.
  3. The armour must be sleeved with green/yellow tape and left unconnected at each enclosure.
  4. The armour must be cut back at both ends and the CPC taken from the internal cores only.

Explanation

Where the armour is used as the CPC it must make a reliable electrical connection to the earthing terminal at every termination. A proper gland, with a banjo or earthing nut where required, achieves this. Bonding armour to a neutral conductor would be dangerous and is never permitted.

Question 43Composite Installation

A single-phase 230 V circuit has a design current of 20 A, a cable length of 20 m and a tabulated voltage drop of 18 mV/A/m. What is the voltage drop in the cable?

  1. 7.2 V Correct answer.
  2. 72 V
  3. 0.72 V
  4. 3.6 V

Explanation

Voltage drop is found from millivolts per ampere per metre multiplied by design current and length, then divided by 1000. Here 18 × 20 × 20 ÷ 1000 = 7.2 V. That is about 3.1% of 230 V, which would be acceptable for a power circuit but not for lighting.

Question 44Composite Installation

A cable is run for part of its length through loft thermal insulation. What is the effect and the correct response?

  1. The capacity rises, so the protective device rating may be increased.
  2. The insulation resistance falls, so the circuit needs RCD protection.
  3. The capacity falls, so the cable must be selected with a derating factor applied. Correct answer.
  4. There is no effect provided the insulation is less than 100 mm thick.

Explanation

Thermal insulation traps heat, so the cable cannot dissipate heat as freely and its current-carrying capacity is reduced. A derating factor must be applied so that the derated capacity remains at least equal to the protective device rating. The thickness of the insulation affects the severity but does not remove the requirement.

Question 45Composite Installation

End-to-end continuity tests on a ring final circuit give r1 = 0.80 Ω and r2 = 1.20 Ω. What is the expected (R1+R2) reading at a socket outlet?

  1. 0.50 Ω Correct answer.
  2. 2.00 Ω
  3. 0.25 Ω
  4. 1.00 Ω

Explanation

With the line and CPC cross-connected, the resistance at each socket is one quarter of the sum of the end-to-end readings. Here (0.80 + 1.20) ÷ 4 = 0.50 Ω. Readings that rise progressively around the ring indicate a poor connection or a broken conductor.

Question 46Composite Installation

What test voltage and minimum acceptable value apply to the insulation resistance test of a 230/400 V final circuit?

  1. 250 V DC and 0.5 MΩ
  2. 500 V DC and 1 MΩ Correct answer.
  3. 500 V DC and 0.5 MΩ
  4. 1000 V DC and 1 MΩ

Explanation

Circuits operating at up to 500 V are tested at 500 V DC with a minimum acceptable result of 1 MΩ. The 250 V DC test with a 0.5 MΩ minimum applies to SELV and PELV circuits. A 1000 V DC test is used for circuits above 500 V.

Question 47Composite Installation

A 32 A type B miniature circuit breaker will operate in its instantaneous (magnetic) range at which multiple of its rated current?

  1. Between 5 and 10 times
  2. Between 10 and 20 times
  3. Between 3 and 5 times Correct answer.
  4. Between 1.13 and 1.45 times

Explanation

Type B devices are designed to trip magnetically between three and five times their rated current. Type C covers five to ten times and type D covers ten to twenty times. The 1.13 to 1.45 range describes the thermal characteristic, not the magnetic one.

Question 48Composite Installation

What is the maximum total amount of bend permitted in a run of steel conduit between draw boxes or other accessible points?

  1. The equivalent of four 90° bends (360°) Correct answer.
  2. One 90° bend
  3. No limit, provided a draw wire is installed
  4. The equivalent of six 90° bends (540°)

Explanation

A conduit run must be limited to the equivalent of four quarter bends, that is 360° in total, between access points. Beyond this, cables cannot be drawn in without damage. Additional draw boxes must be inserted to break the run into shorter sections.

Question 49Composite Installation

A cable passes through a fire-resisting wall inside a steel conduit. What is required at the point of penetration?

  1. The hole must be sealed with a fire-stopping material that maintains the fire resistance of the wall. Correct answer.
  2. The cable must be derated to allow for reduced ventilation.
  3. Nothing, provided the conduit is earthed.
  4. The conduit must be sealed with tape at both ends.

Explanation

Where a wiring system passes through a fire-separating element, the opening must be sealed to maintain the fire resistance of that element. This applies whether or not the conduit is earthed. Earthing the conduit has no bearing on the fire performance of the wall.

Question 50Composite Installation

A hole is to be drilled in a timber floor joist to carry a cable. Where should it be positioned?

  1. On the neutral axis, with a diameter up to a quarter of the joist depth. Correct answer.
  2. In the bottom edge of the joist, directly above a supporting wall.
  3. Anywhere in the joist, provided the hole is no larger than 50 mm.
  4. In the top edge of the joist, at least 50 mm from the wall plate.

Explanation

Holes should be drilled on the neutral axis near the centre of the joist, where bending stress is lowest. The diameter should not exceed one quarter of the joist depth. Notches and holes in the top or bottom edges weaken the joist where stress is highest.