2391 Exam

2391-52 Exam

There are 40 questions in this 2391: Initial Verification of Electrical Installations Mock Exam. You must score 60% (24 out of 40) to pass. You may review answers after each question by clicking the 'check answer' button or you can wait until the end of the test for your final score. Good luck!

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2391 Mock Tests

The 2391 course series relates to two complementary disciplines of electrotechnical theory. This is the initial verification of new circuits, and the periodic inspection of existing electrical installations.

The C&G 2391-52 qualification combines these two elements into a simple, condensed course format. However, these subtly different skill-sets are also offered as separate City and Guilds (C&G courses). The C&G 2391-50 offers candidates the initial verification component in isolation, and the C&G 2391-51 provides coaching on periodic testing and inspection.

Nevertheless, candidates are usually encouraged by tutors and stakeholders alike to attend the amalgamated C&G 2391-52. This is because the course offers an efficient solution to learning both competencies, and therefore saves considerable time and money. For reference, the City & Guilds is a renowned skills and certification provider who cater for students in a range of sectors. Their status as a reputable and trustworthy qualification body is unquestionable, and therefore candidates should feel assured in taking their courses.

There are many private institutions which facilitate City & Guilds courses; however, these do fluctuate in terms of cost and quality. Prospective course-takers are therefore encouraged to conduct their own research into learning providers. However, this dynamic only really applies to those engaging in ‘front-loaded’ training. This format of learning refers to those who are not undertaking collegiate programmes or apprenticeships, and are instead self-funding their career journey. For those in apprenticeship schemes, qualification costs will be absorbed into your overall learning framework. This will be financed by your employer.

Thus, this article intends to focus on the C&G 2391-52, as opposed to the individual courses which comprise its content. In particular, we’ll focus on the qualification’s assessment structure. This analysis will include a full breakdown of assessment structure, reference to testing content, and some extremely useful hints and tips to carry forward into your exams.

Course difficulty

This specific course is renowned for being one of the more challenging qualifications in the electrotechnical bracket. Therefore, before attending the module, candidates should ensure they’re motivated, focused, and receptive to new information. The certification awarded at the course’s conclusion is by no way guaranteed. It should be remembered that this is a ‘Level 3’ graded qualification, and therefore, by default, includes stretching and complex content.

Furthermore, its hugely recommended that those looking to attend the C&G 2391-52 have already acquired a strong grasp of electrotechnical theory and practice. Indeed, this qualification is targeted towards those with sector experience, who have solid electrical knowledge and practical capability. Without this foundational base, attendees will most likely find this course, and its resultant assessments, too difficult.

Lastly, it’s worth noting that the C&G 2391-52 replaces the now defunct C&G 2394/95. This was also a combined package containing both strands of aforementioned electrotechnical practice. For those with vastly experienced site or leadership teams, an awareness of this legacy terminology may come in useful.

Assessment structure, format and content of written elements

The examination framework relating to the C&G 2391-52 Level 3 in Initial Verification and Periodic Testing and Inspection has three distinctive parts. The below guide offers an evaluation of each assessment section, including some key watch-outs and advice. Prospective delegates should take ample time to read and digest information on each individual segment of the testing process. These component parts are designed to provide examiners with a holistic, final view on capability. By successfully navigating each element of the test, candidates will not only have demonstrated a raft of practical skills, but also showcased a depth of understanding in relevant theoretical concepts. However, brace yourself, this is not a straight-forward assessment!

Multiple-choice exam

This is an online test. Therefore, if students are sitting the assessment remotely, they’ll need to ensure they have ready access to an internet-enabled device. This is often labelled as the easiest part of the examination timetable, therefore candidates ideally need to acquire a high score in this assessment. This will give them a decent platform to take on the remaining, more complex, challenges.

The exam lasts for two hours, with candidates required to respond to 40 questions within the allotted time period. Therefore, delegates have 3 minutes to address each question. This is a more than ample timeframe to provide controlled and calculated responses to each question asked.

Furthermore, the multiple-choice exam leverages integrated ‘flagging’ software, which serves to support candidates in their responses. This enables delegates to appropriately ‘flag’ any questions they’re struggling to find a response to. At the end of the assessment, students can then go back to these questions, and, at worst, offer an educated guess. Therefore, this tool offers candidates the ability to press on through the exam, without labouring on questions they initially found too difficult. Without it, as has been the case previously, delegates can overly fixate on providing rushed responses, concerned they’ll forget to re-visit ‘problem’ questions at the end of the examination. Still worse, some may skip past the question, duly forget to return, and fail to submit an answer altogether. This software could be a huge blessing in your exam, so use it wisely!

The benefits and pitfalls of ‘open-book’ exams

The test is ‘open-book,’ which means candidates can bring supportive literature into the examination hall or  ‘virtual’ environment. There are two pieces of key documentation that candidates should be in possession of whilst conducting their exam. These are Guidance Note 3: Inspection and Testing, 8th Edition, and the IET 18th edition wiring regulations guide (bs7671). Both of these items relate directly to the subject matter, and will be extremely useful throughout the multiple-choice assessment. They will also have been readily deployed during the initial course structure.

However, delegates should be cautious around how often they exploit these articles during the examination. Crucially, the ‘open-book’ format should be utilised to support responses, not as a crutch for checking answers you know to be correct. Often, whether it be for assurance purposes or otherwise, delegates will dip into document sections to ‘sense-check’ responses.

This tactic should be avoided. Although test duration is ample enough to provide an answer to each question, it does not offer time for what is ultimately a self-grading exercise. If you’re reasonably confident in the answer provided, press onto the next question. Constantly referring back to the document(s) will waste time, is unnecessary, and arrests momentum. Only use the literature when it’s entirely necessary for the purpose of the question, and when you’re genuinely unsure of how to answer.

Don’t be complacent!

Lastly, it’s also worth noting that multiple-choice exams can sometimes be a little misleading in terms of difficulty level. Some questions will require candidates to methodically work through a number of sums, formulas and information to arrive at the correct answer. Therefore, responses won’t always come purely down to technical knowledge, and may require considerable time and focus. By calmly and competently applying the right electrotechnical process or algorithm to each option, delegates can offer the correct response through a process of elimination.

Written examination

The duration of this section is 90 minutes, and involves sculpting hand-written responses, in a narrative style. Therefore, this is often deemed to be the most challenging component of the overall assessment structure. There will be six detailed questions on the paper, relating to developed themes within 2391-52 course content. This permits 15 minutes per response.

However, these answers need to be presented in written prose, so will take a substantially longer time to craft than multiple-choice responses. Furthermore, responses need to be well-structured and flow smoothly, so there needs to be an element of preparation time also factored in. Delegates will be expected to incorporate relevant electrotechnical terminology in their answers. This should be extracted from both pieces of literature referenced earlier (IET wiring regulations and Guidance Note 3). However, this is a closed-book exam, and therefore candidates will not be permitted to refer to these during the test.

This assessment is broken down into two evenly distributed sections.

Section A

This section involves answering three questions on the preparation and execution of testing and inspection. These questions will relate to topics around the design, assessment, and certification of electrical instalments. There will also be reference to generic electrotechnical theory, and to appropriate health & safety practice.

Section B

This segment similarly presents three questions, but this time responses need to be leveraged around a specific electrical instalment located in a given setting. For example, this could be a particular room in a domestic dwelling, or perhaps in a meeting room of a commercial office.

The written part of the assessment is particularly challenging due to the nature and construction of question sets. The themes and specific conditions captured in the first question of each, will correlate through to the second and third questions. This means that if the initial question is approached incorrectly, it could scupper responses for the remaining two. Therefore, although this is useful from a consistency perspective, it still presents delegates with a significant scoring risk. By ‘building’ question content up, examiners are looking to assess whether candidates have a firm grasp on sequencing and process flow.

Candidate approach

Delegates will need to provide answers on all subjects connected to the design, verification, inspection, testing, and certification stages of electrical instalments. Section B is more terminology-hungry than Section A, so individuals should afford special focus on using correct terms in this part of the exam. It’s therefore worth performing a comprehensive review of both the wiring regulations and Guidance Note 3, prior to sitting this test. Candidates should particularly focus on GN3, as this offers the biggest steer on electrotechnical theory and practice in this discipline.

It’s worth noting that Section B (unfortunately!), given its importance, accounts for a colossal 60% of the overall grade. Therefore, ensure you diligently prepare for this part of the assessment.

Comments relevant to both Sections A & B

When writing responses to these challenging questions, make sure that both wording and explanations are clear and concise. In this context, it’s easy to drift into protracted answers, which go off on tangents and become too waffly. Examiners are simply trying to ascertain whether you’ve acquired the relevant knowledge. Therefore, keep answers extremely relevant and to the point. Besides, you only have 15 minutes to construct each response!

Despite these assessments both presenting significant hurdles to acquiring a course pass, candidates should feel confident in overcoming these challenges. If you’ve progressed this far into the course, it’s clear you have an impressive understanding of electrotechnical theory. Furthermore, the module does directly cover all of the content that may appear on this, or any other, of the qualification’s examinations. Therefore, by applying appropriate focus during the learning programme, and, revising thoroughly, delegates can comfortably navigate this test.

Practical Assessment

The practical element is usually covered off towards the latter stages of your course. Again, this contains two separate testing modules, but is broken down a little more cleanly than the written assessment.

Initial Verification

Part 1 covers the initial verification of electrical instalments, i.e., closing-out the original set-up of an electronic circuit. Within this section, subject matter is split into three component testing segments:

  1. Visual inspection
  2. Fault finding within insulation resistance testing
  3. End-to-end testing and inspection process, concluding with the accurate completion of an official Electrical Installation Certificate.

In simplistic terms, the exam assesses a delegates’ capability in approaching, addressing and summarizing the condition of an electrical instalment. The specific process aligned to each ‘segment’ is articulated below:

Visual inspection

Delegates will commence their practical assessment journey by conducting an inspection of a simulated electrical installation. This will be a relatively basic contraption, and be made up of just several demonstration circuits and a single-phase consumer unit.

Within a 30-minute period, candidates will be asked to visually examine the installation, and identify twelve faults that are inconsistent with bs7671 standards. Therefore, in essence, individuals are being challenged to find and articulate an issue, on average, every two and a half minutes. This may sound challenging, but, as this task is purely visual, many faults will likely be fairly obvious on viewing.

There is a myriad list of issues that could be in-play. It would be overly time-consuming to detail every potential fault, but the below list includes some of the most common discrepancies:

  • Incorrect polarity
  • Live wires exposed
  • Incorrect deployment of circuit-breakers
  • Wrong circuit flow within consumer unit. This would mean neutral and earth wiring not in sequence in their respective terminal bars
  • Incorrect colour coding
  • Earth wire omitted
  • Twisted cables
  • Protective bonding conductor missing
  • Danger/hazards not adequately signposted
  • Incorrect or missing labels on protective devices, switches and terminals
  • Incorrect choice of conductors for current-carrying volume
  • Exposed copper in connection of conductors
  • Noticeable damage to any part
  • Earth sleeving missing
  • Loose SWA cleats
  • No identification of switch wires in-play

However, as referenced, this list is not exhaustive. Therefore, candidates will need to appropriately ensure they’re equipped with all fault eventualities prior to their assessment. Remember, this is simply a visual inspection! There is no opportunity for delegates to strip or examine any part of the instalment with their hands, or administer any other physical method of review.

Fault finding within insulation resistance testing

This will centre around the visual inspection of a ‘black box,’ a dummy electrical instalment exclusively used for examination purposes. The advantage of using this device is its flexibility level in relation to electrical conditions. Invigilators are able to apply variant and adjustable fault activity to an independently created circuit.

Delegates will need to apply two actions in the addressing of this task. Firstly, individuals are required to deploy a relevant testing device and assess the simulated circuit. There are a number of elements that need to be accurately executed in order to successfully navigate this task.

Firstly, candidates will need to pick the appropriate equipment to enable them to accurately conduct this test. In this context, this will clearly be a resistance insulation tester. An essential process to remember is the visual inspection of the testing device before use. Launching into a physical assessment of the circuit before doing this will automatically incur a mistake. The delegate must then prepare the resistance insulation tester for use, setting up the appropriate voltage. As this instalment will use a relatively basic single-phase low-voltage circuit, the assessment will need to be undertaken at 500V. As candidates should be aware, this voltage number complies with the guidance given in the wiring regulations. It is therefore aligned to industry-recognised bs7671 standards.

Sequencing and results

Delegates will then have to apply the correct testing sequence, which will look like the following:

Test between L-N

Test between L-E

Test between N-E

When this has been conducted, candidates will gain an understanding of what circuit failure is apparent through their ohms reading. The specific ohms volumes registered would correspond to the following circumstances:

  • Less than 2M ohms, but not as low as 0 ohms. This would suggest that there is potentially some electrical connection between conductors. This means that the instalment is not functioning correctly, and therefore indicates a fault that requires further investigation.
  • 0 ohms. This identifies a definite fault, as this would suggest a ‘short’ (undesirable) circuit connection between conductors.

A reading of more than 2M ohms means the instalment is an ‘open’ circuit. As this would mean that no electrical connection between the conductors is in operation (as is desired), no further action is necessary. However, given that the assessment is designed around fault finding and resolution, you’ll unfortunately not be lucky enough to discover this when testing!

On determining the fault reason, candidates will then have to confidently articulate this issue to the examiner. Furthermore, they will also need to offer appropriate solutions to remedy the problem. In this response, it’s important to be concise, engaging, and use correct bs7671 terminology. Candidates should also demonstrate a firm understanding of the ‘ohm’ scientific measurement.

End-to-end testing and inspection with resultant certification

In this final section of the initial verification module, delegates will be instructed to undertake a full test and inspection of a mock electrical instalment. They will need to conduct this in a competent, compliant, and structured way. Post-testing and inspection, candidates will need to produce an accurately completed Electrical Installation Certificate. This will detail the findings of the process, and accordingly pass or fail the electrical instalment in question. In order to conduct this, you will be allocated 120 minutes.

This time, there will be two sample circuits to assess rather than one. These will be as follows:

  1. 3-phase & neutral board containing the following components:
  • 3-phase motor supply in an armoured cable (DOL starter, no motor connected)
  • Sockets facilitated by a ring circuit
  • Radial circuit to a fused consumer unit via mineral -insulated cable
  • Sub-main supply to a single-phase consumer unit
  1. Single-phase & neutral consumer unit supplying:
  • Lightning circuit with intermediate switch
  • Lightning circuit with dimmer switch
  • Socket outlet facilitated by a radial circuit.

Importance and execution of safe-isolation

Similar to the fault-finding exercise, delegates must remember a key undertaken prior to commencing this activity. This involves performing a safe isolation procedure.

This process is essential before conducting any electrical installation works, in any capacity. Prior to any sort of electrical works, circuits must be isolated, and deemed to be ‘dead’ (basically, not live!). Ultimately, safe isolation is the act of competently and compliantly disconnecting one or several parts of an electrical installation. This can be achieved via a number of different methods. Most commonly, this will be conducted through hitting a simple ‘main’ switch. However, if there is a requirement to isolate only one individual circuit,  the miniature circuit breaker (MCB) will initiate the isolation. This is because this component, located within the supply board, is programmed to automatically trip the circuit if a fault is recognised. In domestic settings, the main fuse is frequently removed for isolation purposes.

Delivering the inspecting and testing process

Candidates must then commence the full inspection and testing procedure, covering each and every assessment element articulated below. They must also execute this in accurate sequencing order.

Correct inspection and testing process (in correct chronological order):

  • Assessment of the general characteristics of the instalment
  • Review of continuity of protective conductors, including an evaluation on condition of protective bonding.
  • Review of continuity of ring final circuit conductors
  • Perform relevant polarity dead tests
  • Perform an insulation resistance test deploying the correct equipment (check testing device visually for faults first)
  • Perform relevant polarity live tests
  • Perform relevant earth fault loop impedance tests
  • Perform relevant prospective fault current tests
  • Perform a phase sequence test
  • Conduct a residual current device test
  • Complete a functional test on the full electrical instalment.

In order to successfully pass this specific assessment, delegates must execute a fully compliant inspection and test of the instalment. As referenced, this needs to be conducted in the exact sequencing order required. As part of this procedure, candidates must ensure that every available part of the installation has been suitably inspected. This includes:

  • All joints and connection attachments
  • Conductors
  • Flexible cables and cords
  • Accessories and switchgear
  • Thermal elements
  • Basic and fault protection devices
  • Enclosures and mechanical protection units
  • Marking and labelling accuracy

Once all of this has been suitably delivered, an Electrical Installation Certificate must be compiled.  This report acts as a declaration to state that the electrical installation is safe to use at the precise moment the inspection and testing was delivered. This must be completed in full and accurate detail.

Periodic Inspection

The second part of the practical assessment specifically relates to periodic inspection, i.e., the inspection and testing of pre-existing electrical instalments. Therefore, this section does not require any focus on initial verification, as this task is clearly reserved for new instalments. This results in this part of the assessment including just two key activities:

  1. Visual inspection
  2. Execution of periodic inspection and testing with an accompanying Electrical Installation Condition Report.

Visual inspection

In similarity to the initial task in the first part of the practical assessment, the periodic inspection section requires candidates to examine a simple installation. Again, this will contain a few demonstration circuits and a single-phase consumer unit.

Under the same time constraints as the earlier assessment, delegates will be required to again visually identify twelve faults that do not comply with the bs7671 regulation. These allude to the same issues articulated earlier. Again, it’s worth remembering that the previous list was not exhaustive.

Periodic inspection and testing with resultant certification

This must, again, be a full and thorough checking of each component part of the mock electrical instalment. It’s perhaps worth noting that in ‘real-world’ conditions, sampling is accepted as an agreeable methodology to conduct this activity. However, the exam is about demonstrating an overall understanding of each testing and inspection stage, and therefore a more all-encompassing approach is required.

Delegates will be presented with an electrical instalment comprised of the same features encountered in the initial verification examination. Individuals will again be allocated 120 minutes to complete this task, and also must remember to perform a safe isolation prior to actioning any tests.

Delegates will need to run through the same sequence process as expressed earlier, again in perfect order.

As this is a periodic test and inspection, findings will need to be captured on an Electrical Installation Condition Report (as opposed to an Electrical Installation Certificate). This documentation has the same rules of engagement as the initial verification certification, and therefore will need to contain a thorough and accurate analysis of works conducted.

Common themes

Delivering practical assessments can be a nerve-wracking and challenging undertaking. Demonstrating a specific, physical skill-set in front of an assessor is not an easy task. However, candidates should remember a couple of key points, which should hopefully serve to reduce some of the pressure.

Firstly, delegates will be suitably trained in all techniques expected to be showcased at the assessment, and also be coached on the relevant accompanying electrotechnical theory. Therefore, in the unfortunate event that nerves takeover, candidates will not just be able to lean on muscle memory, they’ll also be able to reflect on the principles learned during the 2391 course. Thus, at worst, individuals should at least be able to address the task in logical fashion, and offer an educated guess at how to perform the activity. Furthermore, this also means that no ‘new’ information will be presented during their assessment. Therefore, candidates need not worry about the emergence of fresh challenges.

And, secondly, the course duration has been appropriately extended to factor in the added complexity of the subject matter. Therefore, delegates will receive ample coaching and support, and have plenty of time to make sure they’re as well-placed as possible to tackle the assessment.

Although the above measures do not guarantee safe passage through the tests, they at least should offer a considerable degree of comfort.

Indeed, if you’re relaxed, prepared and confident, there’s no reason why you can’t pass the practical assessments with flying colours.


The C&G 2391-52 testing schedule is amongst the hardest in electrotechnical training. These comprehensive assessments will certainly put delegates through the ringer, and really determine whether they’ve grasped the practical skills and theoretical knowledge related to verification, inspection and testing.

The multiple-choice exam offers individuals a great opportunity to build a solid foundation in their scores, prior to taking on the more difficult elements. Although delegates should not become complacent, providing they’ve absorbed course information well, they should be able to easily pass this test.

The written exam is perhaps the most difficult segment. Therefore, it may be worth prospective participants practicing their written style (and handwriting!) prior to conducting the examination. Remember, these questions demand the incorporation of industry-recognised terminology in your responses. The terms expected to be utilised are denoted in the IET wiring regulations (18th edition), and Guidance Note 3 (inspection and testing). As this is a closed-book exercise, ensure you’ve familiarised yourself with this literature, in detail, before heading into the exam.

As we’ve seen, the practical assessments require close attention to detail, and the capability to physically apply skills and knowledge to ‘real-world’ scenarios. Executing these tasks will also need considerable nerve and emotional control. Due to this, it’s worth practicing, as much as possible (and in a safe way), these activities prior to the main event. Although, it must be conceded that generating the conditions of a real assessment is a difficult dynamic to create.

And finally….

Candidates are encouraged to absorb the advice on offer, gain a robust understanding of the content covered, and acquire the relevant, supporting literature. By doing so, there’s no reason why you can’t successfully navigate through the C&G 2301-52 Initial Verification and Periodic Testing and Inspection assessment process.

Indeed, this is a tough undertaking, but with the right attitude, approach, and competency level, candidates can pass these exams, and pick up an elusive qualification on their way to consolidating their role as an electrician.

We wish you the best of luck in all of your 2391 assessments!