Learning the Appendices for the 18th Edition Exam: A Practical Guide to Finding Answers Fast

Ask any experienced electrician what separates candidates who pass the 18th Edition exam from those who run out of time, and the answer is almost always the same: book navigation. The current City & Guilds 2382-26 exam is open-book and uses BS 7671:2018+A4:2026. Nowhere is fast navigation more important than the appendices.

 

There are always questions on the appendices — around half a dozen — and they are some of the most answerable marks on the paper if you know where to look. The problem is that most candidates treat the appendices as an afterthought. This guide fixes that.

 

There are really three ways to answer an exam question. You can flick through the book at random and hope it falls open on the right page. You can read it cover to cover and hope something sticks. Or you can understand how the book is put together and find the answer logically, well within your two-minute-per-question allowance. Only the third method works reliably — and the appendices reward it more than any other part of the book.

Start with the Contents Page

Before any appendix work, learn to use page 3 — the contents page. It isn’t there for decoration; it’s your shortcut to the middle of the book. At the bottom of page 3 sits the full appendices list, each entry showing the appendix title and the page it begins on.

 

Exam questions almost always give you a clue to where the answer lives. Very often the question contains one or more key words that appear in a section or appendix title — “regulations”, “flexible”, “grouping”, “thermal insulation” — and those words lead you straight to the right part of the book.

 

Exam tip: Read the question, pick out the key word, then scan the contents page for the appendix whose title contains it. This single habit gets you within a page or two of the answer before you’ve even opened the book properly.

 

For a deeper look at this technique across the whole book, see our guide on using the contents page and index to find answers fast.

 

Appendix 1 — The Numerical List of British Standards

Appendix 1 (starting around page 385) is a numerical list of the British Standards referenced throughout BS 7671. Questions here come in one of two styles:

 

Style	The Question Gives You	You Select
1	A British Standard number	The correct title from four options
2	A British Standard title	The correct number from four options

 

The key to speed is knowing the ordering: all the plain BS numbers come first, then the BS EN numbers, and finally the rest. Remember that and you’ll cut your search time dramatically.

 

Remember: When matching a title, compare the wording option by option. Does it match A? No — move on. B? No — move on. C? Yes — tick it and go. You do not need to know what the standard actually covers. Save the analysis for after the exam.

 

Appendix 2 — Statutory Regulations and Memoranda

Appendix 2 (around page 406) covers the statutory regulations and associated memoranda relevant to BS 7671, and it appears more often than candidates expect. It’s where you’ll find things like the requirements of the Plugs and Sockets (Safety) Regulations, and the definition of the nominal UK supply voltage.

 

Fact from Appendix 2	Value
Nominal low-voltage supply (from 1 Jan 1998)	230 V AC, +10% / −6%
Basis for calculations in the exam	230 V nominal (even though you’ll often measure 240 V+ on site)

 

The navigation trick is the same: the question mentions “regulations”, so go to page 3, find the appendix with regulations in its title, and you’re in the right place. There’s only one.

 

Appendix 3 — Time/Current Characteristics

Appendix 3 (from around page 409) contains the time/current characteristics of overcurrent protective devices — fuses, circuit breakers, RCDs and RCBOs. It’s a collection of charts (the response curves) and small tables, called figures.

 

For the exam, the part that matters is the table at the top right of each page. For a given device rating, it tells you the minimum fault current needed to trip within the required disconnection time.

 

To Answer an Appendix 3 Question	Do This
Identify the device type and standard	e.g. Type B circuit breaker to BS EN 60898
Find the correct figure for that device	Turn through Appendix 3 until the heading matches
Read the top-right table	Find the device rating in the left column
Read across	The current for the required operating time

 

For example: a 16 A Type B breaker to BS EN 60898 required to disconnect within 0.4 s needs a fault current of 80 A to flow (figure 3A4). A 20 A semi-enclosed fuse to BS 3036 with a 5 s maximum operating time needs 60 A (figure 3A2). These tables are also what the maximum Zs values in Part 4 are derived from — which is exactly why the 80% rule and the maximum Zs tables matter so much for verification.

 

Key point: You never have to calculate the Zs from these curves in the exam — Part 4 has already done that for 230 V and 55 V systems. Appendix 3 is about reading the required trip current, nothing more.

 

Appendix 4 — The One You Must Know

If you learn to navigate only one appendix, make it Appendix 4. It’s filled with the practical data you use on site, and you are all but guaranteed a question on it.

 

The single most useful page is the first page of Appendix 4 (around page 420), which acts as an index in two halves:

 

Half of Page 420	What It Points You To
Top half	Where to find the rating factor tables — Ca, Cs, Cg, Cd and so on
Bottom half	Cable types, and which table gives current ratings, sizes and voltage drop

 

Beyond that index, Appendix 4 contains:

 

• The calculation for minimum cable size using the rating factors
• The maximum voltage drop percentages for different nominal voltages
• Derating factors for cables in thermal insulation
• Permitted and non-permitted installation methods for each conductor type
• Table 4A3, which gives the BS number for a cable type and points to its rating table
• The full rating factor tables (Ca, Cg, Cs, Cd)
• From page 448 onward, the current-carrying capacity and voltage drop tables for every cable type — twin and earth, singles, armoured, multicore and flexible

 

Important: Don’t try to memorise Appendix 4’s numbers. Memorise its structure — specifically that the first page tells you which table to open. That’s the skill the exam tests. Our guide on installation reference methods and reading Appendix 4 correctly walks through this in detail.

 

Worked Appendix 4 Questions

Here’s how the navigate-first method plays out on real question types:

 

Question	Where You Go	Answer
Derating factor for a cable surrounded by 100 mm of insulation	Item 2.6, page 423 (valid up to 10 mm²)	0.78
Twin and earth clipped to a joist above a ceiling with ≤100 mm insulation — which installation method?	Table 4A2, page 437	Method 100
Ca for a 70 °C thermoplastic copper conductor in 40 °C ambient	Table 4B1, page 441	0.87
Cg for a cable bunched with four others (five in total)	Table 4C1, page 443	0.60
Max current-carrying capacity of 2.5 mm² twin and earth, method 102	Table 4D5, page 456	21 A
Max mass a 1.5 mm² twin flexible cable can suspend	Table 4H3A, page 470	5 kg

 

Notice the pattern: every one of these was solved by matching a key word in the question — “insulation”, “twin and earth”, “thermoplastic”, “bunched”, “flexible” — to the right table via the first page of Appendix 4 or the contents page. No memorised values required.

 

Exam tip: “Bunched with four others” means five cables in total. Small wording traps like this cost marks even when your navigation is perfect — read the question twice.

 

The Appendices Worth Tabbing

You don’t need to tab all 17 appendices. Prioritise the ones that carry marks and that you’ll reference under time pressure:

 

Appendix	Contents	Why Tab It
Contents (p3)	Full appendices list	Your starting point for every question
Appendix 1	Numerical list of BS/BS EN standards	Fast title-to-number matching
Appendix 2	Statutory regulations, 230 V nominal	Comes up more than expected
Appendix 3	Time/current characteristics	Trip-current lookups
Appendix 4 (first page)	Table index for cables and factors	The single most-used page
Appendix 4 tables	Current capacity, voltage drop, rating factors	Almost guaranteed question

 

Then practise navigating your tabbed book under time pressure. Finding a table quickly is a physical skill, and it only comes with repetition.

 

How to Study the Appendices

The appendices reward little-and-often practice far more than cramming. A page or two a day, working through real questions and confirming answers in the book, builds the navigation reflex you need on exam day.

 

Key point: Understanding the appendices — and knowing which one a question points to — is worth around six marks. On a paper where the pass mark is 36 out of 60, that’s a meaningful chunk of your result from a part of the book most candidates neglect.

 

Work the rating factor calculations alongside your table practice, too. The appendices feed directly into cable sizing, so pairing them with the three essential formulas for the exam — adiabatic, voltage drop and rating factors — turns isolated lookups into genuine understanding.

 

Practice and Further Study

The appendices show up across the whole exam, so the best preparation is repeated, timed practice with questions that force you to open the book and find the answer. Test your navigation and your knowledge across the key parts:

 

• Part 4 — Protection for Safety quiz
• Part 5 — Selection and Erection of Equipment quiz
• Part 6 — Inspection and Testing quiz
• Part 7 — Special Installations quiz

 

Our app includes 690+ practice questions covering all 8 parts with detailed explanations referencing specific regulation and appendix numbers, plus full mock tests with the same weighted question distribution as the real exam — the ideal way to drill your book-navigation speed under timed conditions.

 

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