· Part 5
Chapter 54 Earthing and Bonding: Exam Questions and Answers Explained
Master Chapter 54 for the 18th Edition exam — Tables 54.1, 54.7 and 54.8, the adiabatic equation, and supplementary bonding sizes, with worked answers.
Read more →IET Wiring Regulations Study Blog
Expert tips, study strategies, and insights to help you prepare for the IET Wiring Regulations exam.
· Calculations
Cable Size Calculations: The Six-Step Method for the 18th Edition Exam
Master cable sizing with the six-step method: design current, device rating, rating factors, tabulated capacity, voltage drop and the final check.
Read more →
· Exam Tips
Ten Essential BS 7671 Tables for the 18th Edition Exam
The ten BS 7671 tables that appear in almost every 18th Edition exam — Zs limits, k values, CPC sizing, insulation resistance — with worked examples.
Read more →
· Part 4
TN-C-S Earthing System Explained: PME, Ze and PEN Faults
TN-C-S earthing explained for UK installations: PME, the PEN conductor, typical Ze, identification, bonding, open-PEN risks, and BS 7671 checks.
Read more → · Part 4
TN-S Earthing System Explained: Diagram, Ze and Identification
TN-S earthing explained for UK installations: the separate neutral and earth path, cable-sheath earth, typical Ze, identification, testing, and comparison.
Read more → · Part 4
TT Earthing System Explained: Earth Electrode, RCD and Ze
TT earthing explained for UK installations: earth electrodes, RCD fault protection, RA × IΔn, resistance values, testing, and comparison with TN systems.
Read more →
· Testing
TT Systems: How to Check R1+R2 Using the Zs and Ze Tables
There are no maximum Zs tables for TT systems in BS 7671 — here's how to derive an acceptable R1+R2 figure from the TN-C-S tables and verify your own wiring.
Read more →
· Part 5
The On-Site Guide: How to Use the Standard Final Circuit Tables
How to use the On-Site Guide tables to pick cable sizes, protective devices, installation methods, and maximum circuit lengths for standard final circuits.
Read more →
· Exam Tips
Learning the Appendices for the 18th Edition Exam: A Practical Guide to Finding Answers Fast
How to use the appendices of BS 7671 in the 18th Edition exam — the contents page shortcut, Appendix 1 to 4 explained, and worked exam questions.
Read more →
· Part 5
Installation Reference Methods and Cable Sizing: How to Read Appendix 4 Correctly
A worked guide to BS 7671 installation reference methods and current-carrying capacity tables — how heat dissipation drives cable sizing for the exam.
Read more →
· Calculations
Three Essential Formulas for the 18th Edition Exam: Adiabatic, Voltage Drop and Rating Factors
Master three key City & Guilds 2382-26 calculations: the adiabatic equation, voltage drop, and cable rating factors, with worked examples.
Read more →
· BS 7671
Amendment 4 to BS 7671: What to Expect and How It Affects Your 18th Edition Qualification
Amendment 4 (BS 7671:2018+A4:2026): key dates, what's changing, whether you need to resit the 18th Edition exam, and what scheme providers expect.
Read more →
· Booking Guide
How to Book the IET Wiring Regulations Test in 2026
How to book the IET Wiring Regulations test — the current City & Guilds 2382-26 exam code, approved centres, remote exams, costs, and documents.
Read more →
· Exam Tips
Using the Contents Page and Index to Find Answers Fast in the 18th Edition Exam
A method for navigating BS 7671 fast under exam pressure — use the contents page as a map, link part-chapter-reg numbers, and pair it with the index.
Read more →
· Testing
Ring vs Radial Circuit Testing: Why the Methods Differ and How to Get the Numbers Right
A practical guide to testing ring and radial circuits for the 18th Edition exam — cross-connection, R1+R2 readings, the MAD formula, and BS 7671 tests.
Read more →
· Part 7
Special Locations in BS 7671: Bathrooms, Swimming Pools, and More
A guide to Part 7 of BS 7671 — bathrooms, swimming pools, saunas, and construction sites, with the zoning rules and RCD requirements for the exam.
Read more →
· Part 4
Circuit Design and Overload Protection: Revision Notes for the 18th Edition
Revision guide to BS 7671 circuit design and overload protection — the Ib ≤ In ≤ Iz rule, the I2 ≤ 1.45 × Iz check, cable sizing, and voltage drop.
Read more →
· Part 4
RCD Protection: 30 mA Rules and Device Types
BS 7671 RCD protection explained: 30 mA requirements, fault versus additional protection, RCD types, trip thresholds, and circuit selection.
Read more →
· Part 5
Earthing and Bonding Explained: Key Concepts for the 18th Edition Exam
Master earthing and bonding for the 18th Edition exam — earthing vs bonding, TN-S/TN-C-S/TT systems, main and supplementary bonding, and key regs.
Read more →
· Study Guide
BS 7671 Section by Section: A Revision Breakdown for the 18th Edition Exam
A structured 2382-26 revision breakdown of every part of BS 7671:2018+A4:2026, showing where to focus for the 18th Edition exam.
Read more →
· Practice Questions
Free 18th Edition Practice Questions: Test Yourself Before the Exam
Free BS 7671 practice questions with explained answers for 18th Edition revision, including guidance for the current City & Guilds 2382-26 exam.
Read more →
· Exam Tips
18th Edition Exam Pass Rate: What the Stats Tell Us (and How to Beat Them)
What is the 18th Edition exam pass rate, why do so many experienced electricians fail, and how to make sure you pass on your first attempt.
Read more →
· Exam Tips
The Most Common 18th Edition Exam Mistakes (and How to Avoid Them)
The top 18th Edition exam mistakes that fail most candidates — misread questions, poor time management, weak book use, and neglected topics, with fixes.
Read more →
· Study Guide
How Long Should You Study for the 18th Edition? A Realistic Guide
How long to study for the City & Guilds 2382-26 exam, with realistic Amendment 4 revision plans for electricians, students, and career changers.
Read more →
· Exam Tips
18th Edition Exam Questions: Format, Structure, and Question Types Explained
City & Guilds 2382-26 exam format explained: BS 7671 Amendment 4 question types, timing, pass mark, open-book rules, and preparation tips.
Read more →
· Exam Tips
How to Pass the 18th Edition Exam First Time: 10 Tips from Qualified Electricians
How to pass the current City & Guilds 2382-26 BS 7671 exam: Amendment 4 book navigation, mock-test practice, study planning, and common pitfalls.
Read more →
· Part 5
The Adiabatic Equation Explained: How to Check if Your CPC Is Big Enough
A clear explanation of the adiabatic equation S = √(I²t) ÷ k from BS 7671 — what it does, when to use it, and a step-by-step worked example for the IET exam.
Read more →
· Part 4
How to Calculate Cable Size and Protective Device Rating: The BS 7671 Procedure
A step-by-step guide to cable sizing per BS 7671 — design current, protective device selection, correction factors, voltage drop, and Ib ≤ In ≤ It.
Read more →
· Part 6
Continuity of Protective Conductors: The Essential R1+R2 Test Explained
A practical guide to CPC continuity testing per BS 7671 — the R1+R2 and wander lead methods, expected values, and why it's first in the test sequence.
Read more →
· Part 5
The Dangers of a Shared (Borrowed) Neutral: Why Every Circuit Needs Its Own
Why shared neutral conductors are dangerous and prohibited by BS 7671 — overloading, broken neutrals, RCD incompatibility, and isolation failures.
Read more → · Part 4
Earthing and Bonding Explained: TN-C-S, TN-S, TT Systems & BS 7671 Requirements
A guide to electrical earthing and bonding — the three systems (TN-C-S, TN-S, TT), main protective bonding, CPCs, conductor sizes, and BS 7671 regs.
Read more →
· Part 4
7.4 kW EV Charger Cable Size: BS 7671 Worked Example
What cable size does a 7.4 kW EV charger need? Follow a UK BS 7671 worked example covering current, correction factors, voltage drop, and Zs.
Read more →
· Part 7
Installing a PIR Sensor to an Outside Light: Wiring, IP Ratings & BS 7671 Requirements
A practical guide to wiring a PIR motion sensor to an outdoor light — terminal connections, IP ratings, override switches, and the BS 7671 regs.
Read more →
· Part 6
Insulation Resistance Test: Minimum Values and Procedure
BS 7671 insulation resistance test procedure, minimum acceptable values, test voltages, conductor combinations, low readings, and troubleshooting.
Read more →
· Part 4
Maximum Zs and the 80% Rule: Using the Tables Correctly
A guide to maximum earth fault loop impedance and the 80% rule for the IET exam — Table 41.3, why the correction exists, and worked MCB examples.
Read more →
· Part 4
Overload in a Ring Final Circuit: Why a 32A MCB Doesn't Always Protect the Cable
How ring final circuits share current, what happens when the ring breaks, and why a 32A MCB on 2.5mm² cable doesn't fully protect against overload.
Read more →
· Part 6
R1+R2 Ring Final Circuit Test: Why Your Values Don't Match
Getting unequal R1+R2 readings on a ring final circuit? The 3-step test procedure, expected values, and the 5 most common reasons they don't match.
Read more →
· Part 6
Safe Isolation Procedure: The Step-by-Step Process Every Electrician Must Know
A complete guide to the safe isolation procedure — the prove-dead process, GS38 test equipment, locking off, warning labels, and the BS 7671 regs.
Read more →
· Part 4
Supplementary Bonding and Touch Voltage: When, Where, and Why
A practical guide to supplementary equipotential bonding under BS 7671 — touch voltage, when it's required, conductor sizes, and bathroom bonding rules.
Read more →
· Part 6
Zs Test: Procedure, Formula and Maximum Values
How to carry out a Zs test, use the Zs = Ze + (R1+R2) formula, interpret readings, and check maximum permitted values against BS 7671.
Read more →
· Calculations
Transposition of Electrical Formulae: The Maths You Need for the IET Exam
A practical guide to rearranging electrical formulae for the IET exam — Ohm's law, power, Zs, voltage drop, and the adiabatic equation, with examples.
Read more →
· Part 5
Two-Way and Intermediate Switching: How It Works and How to Wire It
A clear guide to two-way and intermediate lighting switching for the IET exam — strappers, cross-over switches, terminal markings, and common faults.
Read more →
· Part 4
What Is an RCD? How It Works, Types, and When BS 7671 Requires One
A complete guide to Residual Current Devices (RCDs) for the IET exam — how they detect faults, RCCB vs RCBO, where 30mA is required, and testing.
Read more →
· Part 6
Part 6: Inspection and Testing - What You Need to Know
A study guide for Part 6 of BS 7671 covering initial verification, periodic inspection, and testing procedures for electrical installations.
Read more →
· Mock Tests
Mock Test Tips: How to Ace the IET Wiring Regulations Exam
Proven strategies and tips for taking the IET Wiring Regulations mock tests. Learn how to manage time, avoid common mistakes, and maximise your score.
Read more →
· Part 7
Guide to Part 7: Special Installations and Locations
Everything you need to know about Part 7 of BS 7671 covering special installations including bathrooms, swimming pools, construction sites, and more.
Read more →
· Part 4
Understanding Part 4: Protection for Safety in BS 7671
A deep dive into Part 4 of the IET Wiring Regulations covering protection against electric shock, thermal effects, overcurrent, and more.
Read more →
· Study Guide
Getting Started with IET Wiring Regulations (BS 7671) Exam Preparation
A comprehensive guide to preparing for the IET Wiring Regulations exam. Learn about the exam structure, key topics, and effective study strategies.
Read more →Study On the Go
Download our app for the complete exam prep experience with practice tests and progress tracking.
