What does City & Guilds 2357 Unit 608 cover?

Unit 608 (Understanding the principles, practices and legislation for diagnosing and correcting electrical faults in electrotechnical systems and equipment in buildings, structures and the environment (ELTK07)) covers 5 main topic areas: The principles, regulatory requirements and procedures for completing the safe isolation of electrical circuits and complete electrical installations; How to complete the reporting and recording of electrical fault diagnosis and correction work; How to complete the preparatory work prior to fault diagnosis and correction work; The procedures and techniques for diagnosing electrical faults; The procedures and techniques for correcting electrical faults. Each topic has specific points you should be able to explain, demonstrate or calculate.

How is this unit assessed?

Assessment for City & Guilds 2357 units typically uses a combination of online multiple-choice exams, written short-answer papers, and practical workshop tasks observed by your tutor. The exact format is set by your college and the awarding body — confirm with your tutor.

When in my apprenticeship will I study this unit?

Level 3 NVQ Diploma in Installing Electrotechnical Systems and Equipment units are typically delivered across the apprenticeship in college-block weeks. Unit 608 is usually delivered to apprentices working through an NVQ pathway with on-the-job portfolio evidence. Check your individual learning plan with your tutor for exact timing.

How long will it take to revise this unit?

A focused revision pass through this checklist typically takes 4–6 hours spread across a week. Apprentices who use Elec-Mate’s mock exams and flashcards alongside the checklist usually find the multiple-choice exam confident within two short revision sessions.

What if I struggle with a specific topic?

Use the linked Elec-Mate guides and calculators in the related-pages section below for any calculation-led topic. For theory-led topics, the BS 7671 18th Edition Guide and IET On-Site Guide are the canonical references. Your college tutor and assessor are also there to help — ask early, not at the end of the unit.

Where does this unit fit in the wider qualification?

Unit 608 is one of several units that together make up the Level 3 NVQ Diploma in Installing Electrotechnical Systems and Equipment. Passing every unit and the end-point assessment (AM2 or equivalent) earns you the full qualification. Check the unit overview in our City & Guilds qualification hub for the full unit list.

UNIT REVISION

City & Guilds 2357 Unit 608: Understanding the principles, practices and legislation for diagnosing and correcting electrical faults in electrotechnical systems and equipment in buildings, structures and the environment (ELTK07) — Complete Revision Guide

A structured revision walkthrough of every topic in City & Guilds 2357 Unit 608 (Understanding the principles, practices and legislation for diagnosing and correcting electrical faults in electrotechnical systems and equipment in buildings, structures and the environment (ELTK07)). 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 through an NVQ pathway with on-the-job portfolio evidence.

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11 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 2357 Unit 608 — Understanding the principles, practices and legislation for diagnosing and correcting electrical faults in electrotechnical systems and equipment in buildings, structures and the environment (ELTK07) — is a core component of the Level 3 NVQ Diploma in Installing Electrotechnical Systems and Equipment.
2This unit is typically delivered to apprentices working through an NVQ pathway with on-the-job portfolio evidence and covers 5 main topic areas.
3Across the 5 topics there are 27 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 principles, regulatory requirements and procedures for completing the safe isolation of electrical circuits and complete 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.

Specify and undertake the correct procedure for completing the safe isolation of an electrical circuit.
State the implications of carrying out safe isolations to: • other personnel • customers/clients • public • building systems (loss of supply).
State the implications of not carrying out safe isolations to: • self • other personnel • customers/clients • public • building systems (presence of supply).
Identify all Health and Safety requirements which apply when diagnosing and correcting electrical faults in electrotechnical systems and equipment including those which cover: • working in accordance with risk assessments/permits to work/method statements • safe use of tools and equipment • safe and correct use of measuring instruments • provision and use of PPE • reporting of unsafe situations..

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02 · Unit Revision

Topic 2: How to complete the reporting and recording of electrical fault diagnosis and correction work

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 reporting and recording information on electrical fault diagnosis and correction work.
State the procedures for informing relevant persons about information on electrical fault diagnosis and correction work and the completion of relevant documentation.
Explain why it is important to provide relevant persons with information on fault diagnosis and correction work clearly, courteously and accurately. 100 City & Guilds Level 3 Diplomas in Electrotechnical Technology (2357) Unit 608 Understanding the principles, practices and legislation for diagnosing and correcting electrical faults in electrotechnical systems and equipment in buildings, structures and the environment (ELTK07).

03 · Unit Revision

Topic 3: How to complete the preparatory work prior to fault diagnosis and correction work

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.

Specify safe working procedures that should be adopted for completion of fault diagnosis and correction work.
Interpret and apply the logical stages of fault diagnosis and correction work that should be followed.
Identify and describe common symptoms of electrical faults.
State the causes of the following types of fault: • high resistance • transient voltages • insulation failure • excess current • short-circuit • open circuit.
Specify the types of faults and their likely locations in: • wiring systems • terminations and connections • equipment/accessories (switches, luminaries, switchgear and control equipment) • instrumentation/metering.
State the special precautions that should be taken with regard to the following: • lone working • hazardous areas • fibre-optic cabling • electro-static discharge (friction, induction, separation) • electronic devices (damage by over voltage) • IT equipment (e.g. shutdown, damage) • high frequency or capacitive circuits • presence of batteries (e.g. lead acid cells, connecting cells)..

04 · Unit Revision

Topic 4: The procedures and techniques for diagnosing electrical faults

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 dangers of electricity in relation to the nature of fault diagnosis work.
Describe how to identify supply voltages.
Select the correct test instruments (in accordance with HSE guidance document GS 38) for fault diagnosis work.
Describe how to confirm test instruments are fit for purpose, functioning correctly and are correctly calibrated.
State the appropriate documentation that is required for fault diagnosis work and explain how and when it should be completed.
Explain why carrying out fault diagnosis work can have implications for customers and clients.
Specify and undertake the procedures for carrying out the following tests and their relationship to fault diagnosis: • continuity • insulation resistance • polarity • earth fault loop impedance • RCD operation • current and voltage measurement • phase sequence.
Identify whether test results are acceptable and state the actions to take where unsatisfactory results are obtained..

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05 · Unit Revision

Topic 5: The procedures and techniques for correcting electrical faults

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 and explain factors which can affect fault correction, repair or replacement.
Specify the procedures for functional testing and identify tests that can verify fault correction..
State the appropriate documentation that is required for fault correction work and explain how and when it should be completed.
Explain how and why relevant people need to be kept informed during completion of fault correction work.
Specify the methods for restoring the condition of building fabric.
State the methods to ensure the safe disposal of any waste and that the work area is left in a safe and clean condition..

06 · 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 2357 Unit 608 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 2357 Unit 608 and every other unit in your qualification.

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.

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.

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.

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.

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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City & Guilds 2357 Unit 608: Understanding the principles, practices and legislation for diagnosing and correcting electrical faults in electrotechnical systems and equipment in buildings, structures and the environment (ELTK07) — Complete Revision Guide

Key Takeaways

Topic 1: The principles, regulatory requirements and procedures for completing the safe isolation of electrical circuits and complete electrical installations

Get the BS 7671 A4:2026 Cheat Sheet — free

Topic 2: How to complete the reporting and recording of electrical fault diagnosis and correction work

Topic 3: How to complete the preparatory work prior to fault diagnosis and correction work

Topic 4: The procedures and techniques for diagnosing electrical faults

Practise with unlimited mock exams

Topic 5: The procedures and techniques for correcting electrical faults

Study This Unit with Elec-Mate

For apprentices

A Five-Step Revision Plan for This Unit

Read through every topic point once

Map each topic to its calculator or guide

Work through Elec-Mate mock exam questions

Get hands-on time on the bench

Self-explain each topic to a peer

Frequently Asked Questions

What does City & Guilds 2357 Unit 608 cover?

How is this unit assessed?

When in my apprenticeship will I study this unit?

How long will it take to revise this unit?

What if I struggle with a specific topic?

Where does this unit fit in the wider qualification?

Continue reading

BS 7671 18th Edition Guide

insulation resistance guide

earth loop impedance calculator

RAMS template guide

safe isolation guide

Mock Exams for Electricians

AM2 Exam Tips

Apprentice Electrician Salary

Off-The-Job Training Hours

Apprentice Year-by-Year Guide

ECS / JIB Gold Card

What electricians say

One App for Everything!

Fantastic app for electricians

Absolutely amazing

Trusted by electricians across the UK

For Apprentices: Pass City & Guilds 2357 Unit 608 with Confidence