UNIT REVISION

City & Guilds 5393-03 Unit 112: Practices and procedures for inspection, testing and commissioning in dwellings — Complete Revision Guide

A structured revision walkthrough of every topic in City & Guilds 5393-03 Unit 112 (Practices and procedures for inspection, testing and commissioning in dwellings). 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 apprentices working primarily in domestic environments.

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26 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 5393-03 Unit 112 — Practices and procedures for inspection, testing and commissioning in dwellings — is a core component of the Level 3 Electrotechnical (Dwellings).
  • 2This unit is typically delivered to apprentices working primarily in domestic environments and covers 13 main topic areas.
  • 3Across the 13 topics there are 66 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 single-phase 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.
  • Identify methods and reasons for communicating with relevant people before isolation or when reconnecting the supply.
  • 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 and circuits.
  • Identify the procedure for detecting potential diverted neutral currents.
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02 · Unit Revision

Topic 2: The requirements for initial verification of single-phase electrical installations in dwellings

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 that is required by the inspector to conduct the initial verification of an electrical installation.
03 · Unit Revision

Topic 3: The requirements for completing the inspection of single-phase electrical installations in dwellings, prior to their 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 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 as detailed in the guidance for inspection in BS 7671.
04 · Unit Revision

Topic 4: The requirements for the safe testing and commissioning of single-phase electrical installations in dwellings

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 the BS 7671 and IET Guidance Note 3.
  • Identify the appropriate instrument for each test to be carried out in terms of: a. the instrument is fit for purpose b. identifying the correct scale or setting.
  • Specify the requirements for the safe use of instruments to be used for testing and commissioning, to include: a. checks required to prove that test instruments are safe and functioning correctly b. the requirements for test leads and probes must comply with HSE Guidance GS38 c. the need for instruments to be regularly checked and calibrated.
  • 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 being obtained.
  • 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 to include: a. protective bonding conductors b. circuit protective conductors c. ring final circuit conductors.
  • State the methods for verifying continuity to include: a. protective conductors b. 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 the following can have: a. cables connected in parallel b. variations in cable length.
  • Explain why it is necessary to verify polarity.
  • State the procedures for verifying polarity.
06 · Unit Revision

Topic 6: The requirements for testing energised single-phase 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.
  • 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 to include: a. installations forming part of a TT system b. 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 in single-phase installations.
  • Verify the suitability of protective devices for prospective fault currents.
  • Specify the methods for testing the correct operation of residual current devices.
  • State the need for functional testing.
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 completion of the certification process.
  • Explain the requirements for the recording and retention of completed initial verification documentation in accordance with the BS 7671.
08 · Unit Revision

Topic 8: The requirements for the periodic inspection and testing of existing electrical installations in dwellings

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 condition reports and associated documentation.
  • State the information that must be available to person to enable effective periodic inspection.
  • Describe how to set samples when undertaking periodic inspection and testing.
  • Explain extents, limitations and operating constraints which need considering.
  • Explain the differences between initial verification and periodic inspection and testing.
  • Explain the purpose of condition report codes and situations leading to the use of each code.

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09 · Unit Revision

Topic 9: How to confirm safety of single-phase system and equipment prior to completion of 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 of themselves and others within the work location during the initial verifications process.
  • Check the safety of electrical systems prior to the commencement of inspection, testing and commissioning.
10 · Unit Revision

Topic 10: 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 of an electrical installation 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 based on engineering evaluation of the installation to be verified.
11 · Unit Revision

Topic 11: How to test single-phase 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 their accessories for tests to include: a. continuity b. insulation resistance c. polarity d. earth electrode resistance e. earth fault loop impedance f. prospective fault current g. RCD operation h. functional testing.
  • Evaluate the appropriate tests suitable for the installation to be verified.
  • Carry out tests in accordance with BS 7671, IET On-Site Guide and Guidance Note 3 to include: a. continuity including: i. main protective bonding conductors ii. circuit protective conductors iii. ring final circuits b. insulation resistance c. polarity d. external earth fault loop impedance (Ze) e. system earth fault loop impedance (Zs) f. prospective fault current g. RCD operation including additional protection h. functional testing.
  • Confirm compliance by evaluating and verifying test results.
  • Complete appropriate documentation in accordance with the BS 7671 and IET Guidance Note 3 including Electrical Installation Certificate and associated schedules.
12 · Unit Revision

Topic 12: How to commission single-phase 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.
13 · Unit Revision

Topic 13: How to report on the condition of existing single-phase 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.

  • Identify situations requiring reporting as part of a periodic inspection and test.
  • Apply a suitable report code to situations.
14 · 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 5393-03 Unit 112 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 5393-03 Unit 112 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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