Free notes
The EIC page 2: supply characteristics, earthing and bondingWhat goes in the maximum demand box?
Free from the notes: Sparky’s video on it, the section word for word as members see it, and a PDF to keep.
The notes
Exactly as they are on the site.
The EIC page 2: supply characteristics
Page two is where the installation gets described in numbers. Most of it is ticks.
| Field | What you put |
|---|---|
| Earthing arrangement | TN-S or TN-C-S on most installations — and tick PME if it's TN-C-S. The form lists other arrangements as well, but most installations you meet will be one of these two |
| AC or DC | AC |
| Number of wires | Single-phase two-wire, three-phase four-wire — "wires" means lines plus neutral |
| Nominal voltage | 230 V single phase · 400/230 V three phase (put the 400 in first) |
| Frequency | 50 Hz |
| Maximum demand | The demand after diversity, in amps or kVA. The form says “kVA / A”, so delete the one you’re not using. It is not the main fuse or main switch rating — those have their own boxes. Guidance Note 3, 2.3 |
GN3 · Section 5 · the EIC · example EIC, Figures 5.1–5.3, pp.147–149 ★ BS 7671 · Appendix 6 · model forms
Earthing, bonding and the main switch
Sizing, straight off tables you already know
From the incoming tails
25 mm² tails → earthing conductor 16 mm² → main protective bonding 10 mm² (read the table: Electrician's Guide Table 3.3.2b, PME)
The tables: Electrician's Guide Tables 3.3.2a (TN-S) and 3.3.2b (PME), p.59, or BS 7671 Tables 54.7 and 54.8. 16, 25 and 35 mm² tails all give you a 16 mm² earthing conductor. Main bonding you read off the table too — don't work it out by halving: on PME it's 10 mm² for supplies up to 35 mm².
Connection verified, or continuity verified?
You also tick what's actually bonded: water, gas, oil, structural steelwork, lightning protection. In a domestic property it's usually just water and gas. The material is normally copper.
The main switch, and the sticker that catches everyone
You record the main switch's location, its BS EN number, the number of poles, its rating and its voltage. Poles: two for single phase (line and neutral), four for three phase (three lines and neutral).
EG · Tables 3.3.2a and 3.3.2b · p.59 · earthing and bonding sizes ★ BS 7671 · Tables 54.7 and 54.8 ★ BS EN 60947-3 · the main switch ★
Free section from Sparky Study Notes. The full Level 3 notes, 1,463 practice questions and the video lessons: sparkystudynotes.co.uk
Test yourself on it
The tests are in the members’ area. Get one wrong and it shows you why, and where to revise.
Get new notes and exam tips from Sparky
About one email a fortnight. Unsubscribe any time. Privacy noticeThat was one section. There are 583.
Sparky Study Notes is the whole Level 3 syllabus written up like this: the explanation, the worked example, and where it is in your book. With a video lesson for every part and a practice paper for every exam.
- 583sections of written notes
- 35video lessons
- 1,463practice questions
- 146diagrams, redrawn
- 18th Edition
- Building Regs
- PAT
- Fundamental Inspection & Testing
- Initial Verification
- Periodic Inspection & Testing