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City & Guilds 2391-51 study materials
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City & Guilds 2391-51 practice questions

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Question 1Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Which of the following is a statutory document?

  1. IET Guidance Note 3
  2. The Electricity at Work Regulations 1989 Correct answer.
  3. The IET On-Site Guide
  4. BS 7671 Requirements for Electrical Installations

Explanation

Statutory documents are made under powers granted by an Act of Parliament and are enforceable in law. The Electricity at Work Regulations 1989 were made under the Health and Safety at Work etc. Act 1974 and impose legal duties on duty holders. BS 7671 and the IET publications are technical standards and guidance that carry no statutory force in themselves.

Question 2Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

What is the legal status of BS 7671?

  1. A non-statutory standard used as evidence of legal compliance Correct answer.
  2. A code of practice given legal force by the Building Act 1984
  3. A statutory instrument that applies only to domestic premises
  4. A statutory instrument enforced by the Health and Safety Executive

Explanation

BS 7671 is not made by Parliament or a Minister, so it is not law. It is widely used, however, as a means of demonstrating that the statutory duties in the Electricity at Work Regulations 1989 and the Building Regulations have been met. Its requirements can therefore be used in evidence, but a departure from it is not in itself an offence.

Question 3Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Which of the following places general duties on employers to ensure, so far as is reasonably practicable, the health, safety and welfare at work of their employees?

  1. The Personal Protective Equipment at Work Regulations 1992
  2. The Health and Safety at Work etc. Act 1974 Correct answer.
  3. The Provision and Use of Work Equipment Regulations 1998
  4. The Control of Substances Hazardous to Health Regulations 2002

Explanation

Section 2 of the Health and Safety at Work etc. Act 1974 establishes the general duty of every employer to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all employees. The other instruments listed are made under that Act and deal with specific hazards or equipment.

Question 4Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Regulation 16 of the Electricity at Work Regulations 1989 deals with which of the following?

  1. The reporting of dangerous occurrences
  2. The notification of work to building control
  3. The earthing of exposed conductive parts
  4. Competence to prevent danger and injury Correct answer.

Explanation

Regulation 16 prohibits any person from being engaged in work where technical knowledge or experience is needed to prevent danger or injury unless that person has the necessary knowledge or experience or is adequately supervised. It is the main competence requirement in the Regulations.

Question 5Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

IET Guidance Note 3 is primarily concerned with which activity?

  1. Earthing and bonding design
  2. Inspection and testing Correct answer.
  3. Selection of cables for voltage drop
  4. Protection against overcurrent

Explanation

Guidance Note 3 is the IET's guidance on the inspection and testing of electrical installations and supports the relevant parts of BS 7671. It covers initial verification, periodic inspection and the associated certification and reporting.

Question 6Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

BS 7671 applies to electrical installations operating at voltages not exceeding which value?

  1. 11 kV ac between conductors
  2. 230 V ac between conductors
  3. 1500 V ac between conductors
  4. 1000 V ac between conductors Correct answer.

Explanation

The scope of BS 7671 covers installations with a nominal voltage up to and including 1000 V ac between conductors, or 1500 V dc between conductors. Installations above these levels fall outside the Regulations and are dealt with by other standards.

Question 7Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Regulation 4 of the Electricity at Work Regulations 1989 requires electrical systems to be:

  1. Inspected and tested at intervals not exceeding five years
  2. Fitted with residual current devices at the origin
  3. Of such construction and maintained so as to prevent danger Correct answer.
  4. Certified by a registered third party before being energised

Explanation

Regulation 4 imposes a duty on persons with control of electrical systems to ensure that the systems are of such construction and are maintained so as to prevent danger. It is a general duty of construction and maintenance rather than a prescribed testing regime.

Question 8Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Under the Electricity at Work Regulations 1989, work on or near a live conductor is permitted only where, among other conditions:

  1. Two competent persons are present for the whole of the work
  2. The circuit is protected by a 30 mA residual current device
  3. A permit to work has been issued and countersigned by the duty holder
  4. It is unreasonable in all the circumstances for it to be dead Correct answer.

Explanation

Regulation 14 permits live work only where it is unreasonable in all the circumstances for the conductor to be dead, and where it is reasonable for the work to be carried out live and suitable precautions are taken. All three conditions must be satisfied, so a permit, an RCD or a second person alone will not justify live working.

Question 9Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Regulation 13 of the Electricity at Work Regulations 1989 requires that where conductors are made dead, precautions are taken to prevent them:

  1. Being worked on by more than one person
  2. Becoming live while the work is in progress Correct answer.
  3. Being earthed at the origin of the installation only
  4. Being inspected more than once a year

Explanation

Regulation 13 requires suitable precautions to prevent a conductor that has been made dead from becoming electrically charged during the work and, where applicable, when it is not being worked on. This normally involves secure isolation, proving dead and, where necessary, earthing.

Question 10Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Under Part P of the Building Regulations, which of the following types of work in a dwelling in England is notifiable?

  1. Replacing a damaged light switch
  2. Replacing a broken ceiling rose
  3. Installing a complete new circuit for a garden shed Correct answer.
  4. Replacing a damaged socket outlet with an identical one

Explanation

In England, notifiable electrical work includes the installation of a new circuit, the replacement of a consumer unit or similar device, and certain work in special locations. Like-for-like replacement of accessories and repair or maintenance work are not notifiable.

Question 11Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

The Electricity Safety, Quality and Continuity Regulations 2002 place duties primarily on which group?

  1. Electrical contractors carrying out periodic inspection
  2. Local authority building control bodies
  3. Distributors and suppliers of electricity Correct answer.
  4. Owners of domestic premises

Explanation

The ESQCR 2002 regulate the supply of electricity and impose duties on distributors and suppliers, covering such matters as voltage and frequency limits, earthing arrangements and continuity of supply. Duties on installers and premises owners derive from other legislation, chiefly the Electricity at Work Regulations 1989 and the Building Regulations.

Question 12Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Which of the following would be reportable as a dangerous occurrence under RIDDOR?

  1. A circuit breaker tripping due to overload with no damage
  2. An electrical short circuit causing a fire Correct answer.
  3. A 30 mA RCD operating during a test
  4. A luminous tube sign failing to strike

Explanation

RIDDOR lists certain electrical events as reportable dangerous occurrences, including an electrical short circuit or overload that causes a fire or explosion. Correct operation of protective devices and routine test operations are not reportable.

Question 13Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Which Regulations require an employer to make a suitable and sufficient assessment of the risks to health and safety arising from their work activities?

  1. Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013
  2. Management of Health and Safety at Work Regulations 1999 Correct answer.
  3. Health and Safety (First-Aid) Regulations 1981
  4. Personal Protective Equipment at Work Regulations 1992

Explanation

The Management of Health and Safety at Work Regulations 1999 require employers to assess the risks to workers and others affected by their undertaking, and to record the significant findings where they employ five or more persons. Risk assessment underpins the selection of precautions taken during inspection and testing work.

Question 14Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Which statement correctly describes the relationship between Part P of the Building Regulations and BS 7671?

  1. Part P covers all the premises within the scope of BS 7671
  2. BS 7671 overrides Part P where the two conflict
  3. Compliance with BS 7671 guarantees compliance with Part P
  4. Adopting BS 7671 can demonstrate compliance with Part P Correct answer.

Explanation

Part P sets the legal requirement for reasonable provision for safety in electrical installations in dwellings, while BS 7671 provides the detailed technical rules. Approved Document P recognises that designing and installing to BS 7671 is a way of satisfying Part P, but it is not the only route and cannot guarantee compliance in every respect.

Question 15Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Under the Electricity Safety, Quality and Continuity Regulations 2002, the declared low voltage single-phase supply of 230 V may vary within which limits?

  1. +6% / −10%
  2. +10% / −6% Correct answer.
  3. ±6%
  4. ±10%

Explanation

The ESQCR prescribe a declared voltage of 230 V with a permitted variation of +10% / −6%, giving a range of approximately 253 V to 216 V. This asymmetric tolerance reflects the historical harmonisation of UK and European supply voltages.

Question 16Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Which HSE publication gives guidance on voltage detectors and test lamps used by electricians?

  1. GS38 Electrical test equipment for use by electricians Correct answer.
  2. HSG85 Electricity at work: safe working practices
  3. HSR25 Memorandum of Guidance on the Electricity at Work Regulations
  4. INDG231 Electrical safety and you

Explanation

GS38 is the HSE guidance document covering the construction, selection and use of test equipment such as test lamps and voltage detectors, including the requirements for fused test leads and accessible probe tips. It is commonly referred to when selecting equipment for proving dead.

Question 17Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Where the HSE Memorandum of Guidance on the Electricity at Work Regulations is not followed, what is the legal position?

  1. It does not create offences but can be used as evidence Correct answer.
  2. It replaces the Regulations in the premises where it is applied
  3. It has no legal standing and cannot be referred to in court
  4. It is a statutory code, so any departure from it is an offence

Explanation

The Memorandum is guidance, not legislation; only the Regulations themselves create offences. Failure to follow guidance is not in itself an offence, but a court may take the guidance into account when deciding whether a duty holder has failed to comply with the Regulations.

Question 18Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Which Regulations require work equipment to be maintained in an efficient state, in efficient working order and in good repair?

  1. The Building Regulations 2010
  2. The Management of Health and Safety at Work Regulations 1999
  3. The Electricity at Work Regulations 1989
  4. The Provision and Use of Work Equipment Regulations 1998 Correct answer.

Explanation

Regulation 5 of PUWER 1998 requires work equipment to be maintained in an efficient state, in efficient working order and in good repair, with any necessary log of maintenance kept. For electrical equipment this supports, and is supported by, the maintenance duty in regulation 4 of the Electricity at Work Regulations.

Question 19Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Which IET publication gives practical guidance and standard circuit arrangements for domestic and similar installations?

  1. IET Guidance Note 5
  2. The IET On-Site Guide Correct answer.
  3. IET Guidance Note 3
  4. The IET Code of Practice for In-service Inspection and Testing

Explanation

The On-Site Guide is the IET's practical companion to BS 7671, presenting standard circuit arrangements, tables and worked guidance for typical domestic and similar installations. It is non-statutory guidance and does not replace the requirements of BS 7671.

Question 20Statutory and non-statutory regulations, standards and guidance applicable to inspection and testing

Under the Health and Safety at Work etc. Act 1974, which duty is placed on employees while at work?

  1. To take reasonable care of themselves and of others affected Correct answer.
  2. To ensure that the installation complies with BS 7671
  3. To provide a written risk assessment before every job is started
  4. To appoint a competent person to supervise all work

Explanation

Section 7 of the Act requires employees to take reasonable care for their own health and safety and that of others who may be affected by their acts or omissions, and to co-operate with their employer so far as is necessary to enable duties to be met. These duties apply alongside the employer's duties and are not transferred to the employee.

Question 21Safe isolation, safety management and safe working practices on site

What is the correct first step when carrying out safe isolation of a circuit?

  1. Fix a warning notice to the distribution board
  2. Test the voltage indicator on a proving unit
  3. Identify the circuit and its isolation device Correct answer.
  4. Operate the main switch at the origin of the installation

Explanation

Safe isolation starts with identifying exactly which circuit is to be worked on and which device isolates it, so that the correct point of isolation is used. Operating devices, fitting locks and notices, and proving the tester all follow once the correct isolation point is known.

Question 22Safe isolation, safety management and safe working practices on site

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

  1. 6 mm
  2. 3 mm
  3. 2 mm
  4. 4 mm Correct answer.

Explanation

GS38 limits the exposed metal tip of test probes to no more than 4 mm, and recommends shorter tips where practicable, to reduce the chance of short circuits and contact with adjacent live parts. Finger guards and shrouded, fused leads complete the protection.

Question 23Safe isolation, safety management and safe working practices on site

After proving a circuit dead with an approved voltage indicator, what must be done before work begins?

  1. Re-prove the indicator on a known source or proving unit Correct answer.
  2. Switch the circuit breaker back on briefly
  3. Apply insulating tape over the conductors
  4. Record the readings in the site log

Explanation

The indicator must be proved before use and re-proved immediately afterwards, so that a tester that has failed during the test cannot give a false dead result. Only when the indicator still operates correctly can the dead test be relied upon.

Question 24Safe isolation, safety management and safe working practices on site

When a padlock has been fitted to secure an isolation, who should hold the key?

  1. The client's duty holder
  2. The person carrying out the work Correct answer.
  3. The site supervisor, whether or not they are working on the circuit
  4. Whoever is nearest to the distribution board

Explanation

The key must stay in the possession of the person working on the circuit, so that nobody else can restore the supply while the work is in progress. Where several people work on the same isolation, each fits a personal lock to a multi-lock hasp.

Question 25Safe isolation, safety management and safe working practices on site

Which notice should be fixed at the point of isolation while work is in progress?

  1. Do not switch on - men working Correct answer.
  2. Danger - high voltage
  3. Fire exit - keep clear
  4. Authorised persons only

Explanation

A warning notice stating that the circuit must not be switched on because people are working on it is fixed at the isolation point alongside the lock. It warns others who may not know the work is taking place not to re-energise the circuit.

Question 26Safe isolation, safety management and safe working practices on site

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

  1. Isolate the supply before touching the casualty Correct answer.
  2. Start CPR immediately without moving them
  3. Throw water over the conductor to break contact
  4. Pull the casualty clear by their clothing

Explanation

The supply must be isolated before the casualty is touched, otherwise the rescuer becomes part of the circuit and may also be electrocuted. If isolation cannot be achieved quickly, an insulated object may be used to separate the casualty from the conductor.

Question 27Safe isolation, safety management and safe working practices on site

When proving a single-phase circuit dead at the point of work, which tests are required?

  1. Line to neutral only
  2. Between the lines of adjacent circuits
  3. Line to earth only
  4. All three combinations: L-N, L-E and N-E Correct answer.

Explanation

Dead testing must be carried out between every pair of conductors that could be at different potentials, which for a single-phase circuit means line to neutral, line to earth and neutral to earth. Testing only one pair could miss a conductor that is still live.

Question 28Safe isolation, safety management and safe working practices on site

Why should a short wait be allowed after isolating a circuit with long cable runs or large capacitors before proving dead?

  1. The breaker mechanism needs time to settle
  2. Stored charge may still be present after isolation Correct answer.
  3. The cable insulation needs time to cool
  4. The indicator needs time to self-calibrate

Explanation

Capacitance in long cables, capacitor banks and electronic equipment can hold a dangerous charge after the supply is removed. A suitable delay, or an approved discharge procedure, allows the charge to decay before the circuit is proved dead.

Question 29Safe isolation, safety management and safe working practices on site

Why is a non-contact voltage detector unsuitable as the sole means of proving a circuit dead?

  1. It is not permitted on domestic installations
  2. It can only be used on earthed systems
  3. It cannot detect alternating voltages
  4. It may fail to indicate a voltage, giving a false dead reading Correct answer.

Explanation

Non-contact detectors can be affected by screening, capacitative coupling and low battery condition, so they may fail to respond to a live conductor. An approved voltage indicator tested against a known source, or proving unit, is required to prove dead.

Question 30Safe isolation, safety management and safe working practices on site

Why must the neutral conductor of a single-phase circuit be proved dead as well as the line conductor?

  1. The RCD does not monitor the neutral
  2. Neutrals are always at earth potential
  3. It can become live if the neutral is disconnected Correct answer.
  4. The neutral carries no current when the load is off

Explanation

A neutral is a live conductor and can rise to a dangerous potential if it is disconnected, if the supply is reversed, or if it is fed from another source. It must therefore be isolated and proved dead like any other live conductor.

Question 31Safe isolation, safety management and safe working practices on site

Before isolating a final circuit in a building fitted with a rooftop PV array and a standby generator, what must be established?

  1. That the PV array has been cleaned recently
  2. That the inverter has been installed correctly
  3. Whether the circuit can be back-fed from another source Correct answer.
  4. That the installation has a valid EICR

Explanation

Alternative sources such as PV, generators, UPS units and standby supplies can keep a circuit energised after the mains isolator is opened. Each source must be identified and isolated, secured and proved dead before work begins.

Question 32Safe isolation, safety management and safe working practices on site

Two electricians are to work on the same isolated circuit. How should the isolation be secured?

  1. A warning notice alone is sufficient
  2. Each person fits their own padlock to a multi-lock hasp Correct answer.
  3. The supervisor holds a single padlock and key
  4. One padlock is shared and the key passed between them

Explanation

Each person must control their own lock so that the isolation cannot be removed until everyone has finished and removed their own lock. A multi-lock hasp allows several padlocks to secure a single isolation point.

Question 33Safe isolation, safety management and safe working practices on site

What is the main purpose of a permit-to-work system for electrical isolation?

  1. To remove the need for proving the circuit dead at the point of work
  2. To record the time and cost of the isolation for the client
  3. To formally confirm that the isolation is safe to work on Correct answer.
  4. To allow unskilled staff to work live under supervision

Explanation

A permit-to-work provides a recorded, authorised statement that the necessary isolations and precautions have been applied before work starts, and it is formally cancelled when work finishes. It supports, but never replaces, physical locking and proof of dead.

Question 34Safe isolation, safety management and safe working practices on site

Under what circumstances does BS 7671 permit work on or near live conductors?

  1. When the circuit voltage is below 230 V
  2. Whenever the circuit is protected by an RCD
  3. When the client accepts the risk in writing
  4. Only where it is unreasonable to work dead and precautions are taken Correct answer.

Explanation

Live work is permitted only where it is unreasonable for the work to be done dead and where suitable precautions, including a risk assessment, competent persons and appropriate PPE, are in place. Convenience or client preference is not sufficient justification.

Question 35Safe isolation, safety management and safe working practices on site

When applying the hierarchy of control to a hazard on site, what should be considered first?

  1. Eliminate the hazard altogether Correct answer.
  2. Write a method statement for the task
  3. Display warning signs around the area
  4. Provide personal protective equipment

Explanation

The hierarchy of control starts with eliminating the hazard, for example by arranging the work to be done dead rather than live. Only when elimination is not reasonably practicable should the risk be reduced, protected against or managed by administrative controls and PPE.

Question 36Safe isolation, safety management and safe working practices on site

What should happen before a method statement is used for a task on site?

  1. It should be prepared by the least experienced member of the team
  2. It should be issued to the client only after the work is finished
  3. Those carrying out the work should have it explained to them Correct answer.
  4. It should be filed in the site office without being discussed

Explanation

A method statement only controls risk if the people doing the work understand it, so it must be briefed to the team, with the opportunity to ask questions, before work starts. It is then followed, and revised if conditions change.

Question 37Safe isolation, safety management and safe working practices on site

Which of the following must be reported to the enforcing authority under RIDDOR?

  1. A damaged socket outlet that has been isolated
  2. A minor cut to a finger while stripping cable
  3. An electrical short circuit that caused a fire on site Correct answer.
  4. A worker arriving late for a shift

Explanation

RIDDOR requires the reporting of specified injuries, dangerous occurrences and certain ill health, and an electrical short circuit or overload causing a fire or explosion is a reportable dangerous occurrence. Minor first-aid injuries and equipment defects that have been made safe are recorded locally instead.

Question 38Safe isolation, safety management and safe working practices on site

Which type of portable fire extinguisher is suitable for a fire in live electrical equipment?

  1. Water
  2. Carbon dioxide Correct answer.
  3. Wet chemical
  4. Foam

Explanation

Carbon dioxide extinguishers are suitable for fires involving live electrical equipment because the gas is non-conductive and leaves no residue. Water, foam and wet chemical extinguishers are conductive and must not be used on live apparatus.

Question 39Safe isolation, safety management and safe working practices on site

When proving a three-phase and neutral distribution board dead at the point of work, which tests are required?

  1. Between each phase and neutral only
  2. Between each phase and earth only
  3. Between one phase and earth as a sample
  4. Between all conductors, in every combination Correct answer.

Explanation

Every pair of conductors that could be at different potentials must be tested, which means each phase to neutral, each phase to each other phase, each phase to earth and neutral to earth. Testing a sample combination could leave an energised conductor undetected.

Question 40Safe isolation, safety management and safe working practices on site

A circuit breaker has been switched off and locked. Why is this not, on its own, enough to make the circuit safe to work on?

  1. The breaker contacts may open too slowly
  2. It may still be live from another source and must be proved dead Correct answer.
  3. The lock may be removed by the client at any time
  4. A circuit breaker does not provide overload protection

Explanation

Switching off and locking does not guarantee the conductors are dead: the circuit may be back-fed, the device may be faulty, or the wrong device may have been operated. The conductors must always be proved dead at the point of work with an approved indicator.

Question 41Safe isolation, safety management and safe working practices on site

The main switch of a consumer unit has been locked off and the outgoing terminals proved dead. Why does work inside the unit remain hazardous?

  1. The incoming supply terminals upstream of the main switch remain live Correct answer.
  2. The neutral bar becomes live when the main switch is off
  3. Locking off causes the main switch to overheat
  4. The main switch can reclose automatically

Explanation

A main switch isolates only the outgoing side of the installation; the incoming meter tails and the supply terminals of the switch stay live. Work inside the enclosure must avoid those barriers and guards, or the supply must be isolated upstream by the distributor.

Question 42Safe isolation, safety management and safe working practices on site

Why does GS38 require test leads to incorporate a fuse or other protective device?

  1. To prevent use on three-phase systems
  2. To increase the sensitivity of the voltage indicator
  3. To reduce the cost of replacing damaged leads
  4. To limit the current if the leads short across a supply Correct answer.

Explanation

If the probes accidentally bridge live parts, the fuse limits the fault current and reduces the energy of the resulting arc, protecting the user from burns and blast. The leads must also be adequately rated and kept in good condition.

Question 43Safe isolation, safety management and safe working practices on site

Which PPE is appropriate when operating a large isolator that may produce an arc?

  1. A dust mask and ear defenders
  2. Arc-rated clothing and a face shield Correct answer.
  3. Ordinary spectacles and rubber gloves
  4. Cotton overalls and safety boots only

Explanation

Switching large isolators can produce an arc with intense heat, molten metal and blast, so arc-rated clothing and a face shield are worn, along with the correct gloves for the task. The risk assessment for the switching operation determines the specific PPE required.

Question 44Safe isolation, safety management and safe working practices on site

What does the CAT III marking on a voltage detector indicate?

  1. It is rated to withstand transient overvoltages expected in that location Correct answer.
  2. It is suitable only for domestic single-phase work
  3. It is able to measure currents up to 1000 A
  4. It is waterproof to IPX3

Explanation

Measurement category markings show the transient overvoltage environment the instrument is designed to withstand, with CAT III covering distribution level circuits such as distribution boards and fixed wiring. The instrument must be rated at least for the category and voltage of the point where it is used.

Question 45Preparation for periodic inspection and testing: documentation, extent, sampling and limitations

Which document is issued to the person ordering a periodic inspection and test of an existing installation?

  1. A Minor Electrical Installation Works Certificate
  2. A Schedule of Inspections
  3. An Electrical Installation Certificate
  4. An Electrical Installation Condition Report Correct answer.

Explanation

Periodic inspection and testing of an existing installation is reported on an Electrical Installation Condition Report, the model form given in BS 7671. The report records the condition of the installation, the observations and classifications, and the recommended date of the next inspection.

Question 46Preparation for periodic inspection and testing: documentation, extent, sampling and limitations

Which information should the inspector request from the client before starting a periodic inspection?

  1. The manufacturer's instructions for the supply transformer
  2. The previous inspection reports and certificates Correct answer.
  3. The building's public liability insurance policy
  4. The supplier's diagram of the local distribution network

Explanation

Existing documentation helps the inspector to establish the extent of the installation, plan the sample and compare earlier results with those obtained now. It should be requested at the preparation stage, before any work begins.

Question 47Preparation for periodic inspection and testing: documentation, extent, sampling and limitations

With whom must the extent of, and limitations to, a periodic inspection be agreed?

  1. The electricity distribution network operator
  2. The manufacturer of the protective devices
  3. The local authority building control body
  4. The person ordering the inspection Correct answer.

Explanation

BS 7671 requires the extent of the inspection and any limitations to be agreed with the person ordering the work before the inspection begins. What has been agreed is then recorded on the report so that readers know what it covers.

Question 48Preparation for periodic inspection and testing: documentation, extent, sampling and limitations

On an Electrical Installation Condition Report, where are parts of the installation that were not inspected or tested recorded?

  1. In the observations and recommendations
  2. In the schedule of test results
  3. In the extent and limitations section Correct answer.
  4. In the declaration on the report

Explanation

The report has a dedicated extent and limitations section describing the parts covered and, importantly, the parts not covered by the inspection. This allows the reader to judge how much of the installation the report actually relates to.

Question 49Preparation for periodic inspection and testing: documentation, extent, sampling and limitations

On a schedule of inspections, the abbreviation LIM indicates that the item:

  1. has a limited service life and must be replaced
  2. was not inspected or tested because of a limitation Correct answer.
  3. has a fault level that is limited and cannot be measured
  4. needs a low-current test instead of a full test

Explanation

LIM is entered against an item that fell within the agreed extent but could not be inspected or tested, for example because of lack of access or because the supply could not be isolated. The reason is described in the extent and limitations section of the report.

Question 50Preparation for periodic inspection and testing: documentation, extent, sampling and limitations

Where a periodic inspection is to be based on a sample, what minimum proportion of the installation does GN3 recommend the sample should cover?

  1. 50%
  2. 25%
  3. 10% Correct answer.
  4. 5%

Explanation

GN3 recommends that a sampling inspection covers at least 10% of the items in the installation, including at least one example of each type of item. The sample is then extended if defects are found.