UNIT REVISION

City & Guilds 2365-03 Unit 304: Electrical Installations: Inspection, Testing and Commissioning — Complete Revision Guide

A structured revision walkthrough of every topic in City & Guilds 2365-03 Unit 304 (Electrical Installations: Inspection, Testing and Commissioning). Use it as a personal study checklist — work through each topic, tick off the points you can confidently explain or calculate, and use the linked Elec-Mate tools to practice the calculation-led parts. Designed for 2nd to 4th-year apprentices.

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24 min readUpdated 2026-05-18Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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Key Takeaways

  • 1City & Guilds 2365-03 Unit 304 — Electrical Installations: Inspection, Testing and Commissioning — is a core component of the Level 3 Diploma in Electrical Installations.
  • 2This unit is typically delivered to 2nd to 4th-year apprentices and covers 11 main topic areas.
  • 3Across the 11 topics there are 59 specific points you should be able to explain, demonstrate or calculate before the end-of-unit assessment.
  • 4Common assessment formats include online multiple-choice exams, written short-answer papers, and practical workshop tasks observed by your tutor.
  • 5Use the structured topic list below as a personal checklist — work through each point and confirm you can explain it without referring to your notes.
  • 6The Elec-Mate apprentice tier includes mock exams, flashcards, and revision notes mapped to this unit. Use the tools to test yourself between college blocks and on-site days.
01 · Unit Revision

Topic 1: The requirements for completing the safe isolation of electrical circuits and installations

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • State the requirements of the Electricity at Work Regulations for the safe inspection of electrical systems and equipment.
  • Specify the appropriate procedure for completing safe isolation.
  • State the reasons for carrying out safe isolation.
  • State the implications of carrying out safe isolation.
  • State the implications of not carrying out safe isolation.
  • Identify the Health and Safety requirements which apply when inspecting, testing and commissioning electrical installations.
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02 · Unit Revision

Topic 2: The requirements for initial verification of electrical installations

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • State the purpose of the Initial Verification of electrical installations.
  • State the requirements of the initial verification.
  • Identify the relevant documents associated with the inspection, testing and commissioning of an electrical installation.
  • Specify the information required by the inspector to conduct the initial verification.
03 · Unit Revision

Topic 3: The requirements for completing the inspection of electrical installations prior to service

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Select appropriate items to be checked during the inspection process.
  • Identify human senses appropriate for initial verification.
  • State how the senses can be used during the inspection process.
  • Specify the requirements for the inspection of electrical installations.
  • Specify the requirements for inspection including special installations and locations as identified in Part 7 of BS 7671 and IP Classification of equipment.
04 · Unit Revision

Topic 4: The requirements for the safe testing and commissioning of electrical installations

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • State the tests to be carried out on an electrical installation in accordance with BS 7671 and IET Guidance Note 3.
  • Identify the appropriate instrument for each test in terms of fitness for purpose and correct scale or setting.
  • Specify the requirements for the safe use of instruments including checks for safety and functioning, test leads complying with HSE GS38, and regular calibration.
  • Explain why it is necessary for test results to comply with standard values.
  • State the actions to be taken in the event of unsatisfactory results.
  • Explain why testing is carried out in the sequence specified in BS 7671 and IET Guidance Note 3.
05 · Unit Revision

Topic 5: The requirements for testing before circuits are energised

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • State why it is necessary to verify continuity of protective bonding conductors, circuit protective conductors, and ring final circuit conductors.
  • State the methods for verifying continuity of protective conductors and ring final circuit conductors.
  • Explain factors that affect conductor resistance values.
  • Specify the procedures for completing insulation resistance testing.
  • State the effects on insulation resistance values that cables connected in parallel and variations in cable length can have.
  • Explain why it is necessary to verify polarity.
  • State the procedures for verifying polarity.
06 · Unit Revision

Topic 6: The requirements for testing energised installations

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • State the procedures for confirming polarity of the incoming supply.
  • State the methods used to verify phase sequence.
  • State the need for functional testing.
  • Identify items which require functional testing.
  • State the appropriate procedures for dealing with clients during the commissioning and certification process.
  • Specify the methods for measuring earth electrode resistance for TT systems, generators and transformers.
  • Describe common earth fault loop paths.
  • State the methods for verifying protection by automatic disconnection of supply.
  • Identify the requirements for the measurement of prospective fault current.
  • Specify the methods for determining prospective fault current.
  • Verify the suitability of protective devices for prospective fault currents.
  • Specify the methods for testing the correct operation of residual current devices.
  • State the reasons for verifying phase sequence.
07 · Unit Revision

Topic 7: The requirements for the completion of electrical installation certificates and associated documentation

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Explain the purpose of certification and associated documentation.
  • State the information that must be contained on initial verification documentation.
  • Describe the certification process for a completed installation.
  • Identify the responsibilities of different relevant personnel in relation to the certification process.
  • Explain the requirements for the recording and retention of completed initial verification documentation in accordance with BS 7671.

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08 · Unit Revision

Topic 8: How to confirm safety of system and equipment prior to inspection, testing and commissioning

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Carry out safe isolation procedures in accordance with regulatory requirements.
  • Comply with the Health and Safety requirements during the initial verifications process.
  • Check the safety of electrical systems prior to commencement of inspection, testing and commissioning.
09 · Unit Revision

Topic 9: How to carry out inspection of electrical installations prior to them being placed into service

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Identify a safe system of work appropriate to the work activity.
  • Carry out an initial inspection in accordance with the requirements of BS 7671 and IET Guidance Note 3.
  • Complete a Schedule of Inspections in accordance with BS 7671 and IET Guidance Note 3.
10 · Unit Revision

Topic 10: How to test electrical installations prior to them being placed into service

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Select the test instruments and accessories for continuity, insulation resistance, polarity, earth electrode resistance, earth fault loop impedance, prospective fault current, RCD operation, phase sequence, and functional testing.
  • Evaluate the appropriate tests suitable for the installation to be verified.
  • Carry out tests in accordance with BS 7671 including continuity, insulation resistance, polarity, external and system earth fault loop impedance, prospective fault current, RCD operation, phase sequence, and functional testing.
  • Confirm compliance by evaluating and verifying test results.
  • Complete appropriate documentation including Electrical Installation Certificate, Schedule of Inspections, and Schedule of Test Results.
11 · Unit Revision

Topic 11: How to commission electrical systems and equipment

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Clarify the commissioning procedures with relevant persons.
  • Carry out the commissioning of circuits, accessories and equipment to confirm functionality.
12 · Unit Revision

Study This Unit with Elec-Mate

Elec-Mate’s apprentice tier turns this unit checklist into an active study plan. You get mock exam questions, flashcards, and revision notes mapped to this unit, plus working calculators for every calculation-led topic. Most apprentices use the app between college blocks and on the train to site — short bursts of revision compound across the year.

For apprentices

The Elec-Mate apprentice tier includes mock exams, flashcards, and revision notes for City & Guilds 2365-03 Unit 304 plus every other unit in your qualification. 7-day free trial — see your progress on the tutor dashboard.

A Five-Step Revision Plan for This Unit

A repeatable approach that works for City & Guilds 2365-03 Unit 304 and every other unit in your qualification.

1

Read through every topic point once

Start at Topic 1 and read every bullet point. Don’t try to memorise — just get familiar with the scope. Note any topic that feels unfamiliar so you can come back to it.

2

Map each topic to its calculator or guide

For calculation-led topics, open the relevant Elec-Mate calculator and try one worked example. For theory-led topics, find the matching section in BS 7671 or the IET On-Site Guide.

3

Work through Elec-Mate mock exam questions

The Elec-Mate apprentice tier includes mock questions mapped to this unit. Aim for 80%+ on a clean run before the real exam.

4

Get hands-on time on the bench

For practical units (inspection and testing, installation), ask your tutor for additional workshop access. The bench is where the points click.

5

Self-explain each topic to a peer

If you can explain a topic in your own words to another apprentice and they understand it, you know it. This is the single highest-leverage revision tactic.

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