UNIT REVISION

City & Guilds 2366-03 Unit 302: Inspection, testing and commissioning of electrotechnical systems and equipment — Complete Revision Guide

A structured revision walkthrough of every topic in City & Guilds 2366-03 Unit 302 (Inspection, testing and commissioning of electrotechnical systems and equipment). 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 Level 3 apprentices.

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16 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 2366-03 Unit 302 — Inspection, testing and commissioning of electrotechnical systems and equipment — is a core component of the Level 3 Diploma in Electrotechnical Technology.
  • 2This unit is typically delivered to Level 3 apprentices and covers 8 main topic areas.
  • 3Across the 8 topics there are 39 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.

  • The requirements of the Electricity at Work Regulations for the safe inspection of electrical systems and equipment.
  • The appropriate procedure for completing safe isolation in accordance with regulatory requirements.
  • The reasons for carrying out safe isolation when working on electrical installations.
  • The issues which may need to be mitigated when carrying out safe isolation.
  • The health and safety requirements and unsafe situations that may arise if these are not complied with.
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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.

  • The requirements of the initial verification of electrical installations in compliance with BS 7671.
  • The relevant documents associated with the inspection, testing, commissioning and reporting of an electrical installation.
  • The information required by the inspector to conduct the initial verification of an electrical installation.
03 · Unit Revision

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

  • Items to be checked during the inspection process.
  • How human senses can be used during the inspection process.
  • Reasons items are checked during the inspection of electrical installations.
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.

  • The reasons why testing is carried out in the relevant sequence specified in BS 7671 and IET Guidance Note 3.
  • The appropriate test instrument and settings to be used during the inspection and testing process for accurate results.
  • The requirements for the safe and correct use of instruments for testing and commissioning.
  • The reasons why it is necessary for test results to conform to standard values in the design, guidance and BS 7671.
  • The actions to be taken in the event of unsatisfactory results being obtained.
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.

  • The reasons why it is necessary to verify continuity of protective and ring final circuit conductors within electrical installations.
  • The methods for verifying continuity within an electrical installation.
  • The factors that affect conductor resistance test values.
  • The procedures for completing insulation resistance testing.
  • The effects of installed cables on insulation resistance values.
  • Reasons for single-pole devices, centre screw lamps and electrical accessories need to have correct polarity verified.
  • The procedures for verifying circuit conductor polarity.
  • The method for measuring earth electrode resistance of supply electrodes and within installations.

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06 · Unit Revision

Topic 6: The requirements for testing energised circuits

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.

  • The procedures for verifying correct polarity of the incoming supply.
  • The test for measuring earth electrode resistance in an energised installation.
  • The common earth fault loop paths.
  • The methods for verifying protection by automatic disconnection of supply.
  • The methods for determining prospective fault current in installations.
  • The suitability of protective devices for prospective fault currents.
  • The tests for the correct operation of residual current devices (RCD).
  • The procedure for verifying phase sequence and the potential consequence of an incorrect sequence.
  • The items which require functional testing/checking when installed and the testing methods used.
07 · Unit Revision

Topic 7: The requirements for the completion of 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.

  • The reasons for issuing certification and documentation.
  • The information that must be contained on inspection and testing certification/documentation.
  • The requirements for the retention of completed inspection and testing certification/documentation.
  • The roles and responsibilities of different relevant personnel in relation to the completion of the Electrical Installation Certificate.
08 · Unit Revision

Topic 8: How to confirm the safety of electrical systems 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.

  • Comply with the health and safety requirements during the initial verification process.
  • Carry out safe isolation procedures.
09 · 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 2366-03 Unit 302 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 2366-03 Unit 302 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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