UNIT REVISION

City & Guilds 2346-03 Unit 115: Apply Fault Diagnosis and Rectification — Complete Revision Guide

A structured revision walkthrough of every topic in City & Guilds 2346-03 Unit 115 (Apply Fault Diagnosis and Rectification). 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 experienced workers consolidating skills outside a formal apprenticeship.

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8 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 2346-03 Unit 115 — Apply Fault Diagnosis and Rectification — is a core component of the Electrotechnical Experienced Worker Qualification.
  • 2This unit is typically delivered to experienced workers consolidating skills outside a formal apprenticeship and covers 3 main topic areas.
  • 3Across the 3 topics there are 18 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: Prepare to carry out fault diagnosis

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.

  • Check it is safe to carry out fault diagnosis.
  • Inform the relevant personnel of the fault diagnosis work (such as personnel on the premises, users of electrical equipment).
  • Carry out the safe isolation procedure.
  • Evaluate and apply appropriate methods to ensure the safety of themselves and others when diagnosing and correcting electrical faults.
02 · Unit Revision

Topic 2: Carry out fault diagnosis

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.

  • Communicate effectively with relevant personnel (eg. customer, premises manager) to ascertain the nature of the fault..
  • Select and interpret appropriate documents (eg. layout drawings, schematic diagrams etc) which relate to the electrical systems and equipment being worked upon.
  • Assess and communicate potential disruption that may be a consequence of fault diagnosis and correction work to relevant people, such as: a. Other workers/colleagues b. Customers/clients..
  • Carry out relevant inspections of electrical equipment analysing findings.
  • Confirm test instruments are fit for purpose, functioning correctly and are correctly calibrated.
  • Perform suitable diagnostic tests, based on engineering decision, to identify electrical faults Assess three from the following: a. Loss of supply b. Overload c. Short-circuit d. Earth fault e. Incorrect phase rotation f. High resistance joints/loose terminations g. Component, accessory or equipment faults h. Open circuit i. Signal faults..
  • Use appropriate methods for locating faults including: a. Using a logical approach b. Using safe working practices c. Interpretation of test readings..
  • Use appropriate instruments correctly to carry out fault diagnosis Assess three of the following: a. Voltage indicator b. Low resistance ohm meter c. Insulation resistance tester d. EFLI and PFC tester e. RCD tester f. Ammeter g. Phase rotation tester h. Other appropriate instrument..
03 · Unit Revision

Topic 3: Carry out fault rectification

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.

  • Assess the appropriate repairs, removals and replacements and their implications with relevant people including: One of the following: a. Other workers/colleagues b. Customers/clients..
  • Perform fault correction procedures correctly and safely using appropriate tools, equipment and material.
  • Assess and verify that replacement components and associated equipment maintain: a. Ease of access to enable future maintenance b. compliance with relevant regulations c. compliance with manufacturer’s instructions/ organisational procedures..
  • Apply appropriate procedures to ensure electrical equipment and components are left safe, in accordance with industry regulations, if the fault cannot be corrected immediately based on technical assessment..
  • Establish and perform an appropriate inspection and testing procedure to confirm that circuits/equipment/components are functioning correctly after completion of fault correction work.
  • Record test results and other appropriate information regarding the fault correction work clearly and accurately and report it to relevant people. Assess one of the following: a. Other workers/colleagues b. Customers/clients City & Guilds Level X Award/Certificate/Diploma in Xxxxxxx (XXXX-XX) 43 Appendix 1 Relationships to other qualifications Links to other qualifications This qualification has connections to the following within the electrical suite offered by City & Guilds: • 2382 • 2391 • 5357 City & Guilds Level 3 Electrotechnical Experienced Worker Qualification (2346-03) Appendix 2 Sources of general information The following documents contain essential information for centres delivering City & Guilds qualifications. They should be referred to in conjunction with this handbook. To download the documents and to find other useful documents, go to the Centre Document Library on www.cityandguilds.com or click on the links below: Centre Handbook: Quality Assurance Standards This document is for all approved centres and provides guidance to support their delivery of our qualifications. It includes information on • Centre quality assurance criteria and monitoring activities • Administration and assessment systems • Centre-facing support teams at City & Guilds / ILM • Centre quality assurance roles and responsibilities. The Centre Handbook should be used to ensure compliance with the terms and conditions of the Centre Contract. Centre Assessment: Quality Assurance Standards This document sets out the minimum common quality assurance requirements for our regulated and non-regulated qualifications that feature centre assessed components. Specific guidance will also be included in relevant qualification handbooks and/or assessment documentation. It incorporates our expectations for centre internal quality assurance and the external quality assurance methods we use to ensure that assessment standards are met and upheld. It also details the.

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04 · 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 2346-03 Unit 115 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 2346-03 Unit 115 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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