Getting Started — Electrical
Purpose
This document is the starting point for electrical work at Wilsons. It covers the regulatory framework, qualifications required, the scope of work we undertake, and the key standards that govern electrical installation in the UK.
The Regulatory Framework
BS 7671 — IET Wiring Regulations (18th Edition)
BS 7671:2018+A2:2022 (the 18th Edition Wiring Regulations) is the standard for all electrical installation work in the UK. Compliance with BS 7671 is the accepted method of demonstrating compliance with the Electricity at Work Regulations 1989 and Building Regulations.
The 18th Edition is the version currently in force. Amendment 2 (2022) introduced significant changes to surge protection, prosumer installations (solar, EVs), and consumer unit requirements. All new installation work must comply.
Building Regulations — Part P
Part P requires that certain electrical work in dwellings is either:
- Carried out by a registered competent person (NICEIC, NAPIT, or Elecsa registered), or
- Notified to Building Control before the work starts
Notifiable work in dwellings includes: Consumer unit replacements, new circuits, work in kitchens, bathrooms, garages, and outdoors.
Non-notifiable work: Like-for-like replacement of accessories (sockets, switches, light fittings) within existing circuits in rooms other than kitchens and bathrooms.
Wilsons is registered with a competent person scheme to self-certify notifiable work without involving Building Control.
Electricity at Work Regulations 1989
A statutory instrument requiring all electrical systems are constructed, maintained, and used to prevent danger. This places a legal duty on employers and employees — electrical work must be carried out safely.
Qualifications and Competency
- Qualified electricians (NVQ Level 3 or equivalent): Can carry out and certify all electrical installation work within their competency
- Engineers under supervision: Can assist but cannot certify installations or sign off test results independently
- EV Charging: Requires additional competency — City & Guilds 2919 or equivalent. Separate from standard Part P.
18th Edition training must be current for all electricians carrying out new installation work.
Wilsons' Scope of Electrical Work
- Consumer unit replacements
- Additional circuits — sockets, lighting, cooker, shower
- First and second fix wiring
- EICRs (Electrical Installation Condition Reports)
- Minor works — additional sockets, FCUs, outdoor sockets
- EV charging point installation
- External/garden power
- Data and comms circuits
Key Concepts
RCDs and RCBOs
RCD (Residual Current Device): Detects imbalance between live and neutral — indicating current leaking to earth (through a person or fault). Disconnects in milliseconds.
RCBO (Residual Current Breaker with Overcurrent protection): Combines RCD + MCB in a single device. Each circuit has its own RCD protection — a fault on one circuit does not trip others.
The 18th Edition strongly favours individual RCBO protection per circuit. Modern consumer units are typically fitted fully with RCBOs.
Consumer Units
The consumer unit (fuseboard) contains:
- Main switch (isolates all circuits)
- Circuit protection devices (RCBOs, MCBs, RCDs)
BS 7671 requires new and replacement consumer units to have a non-combustible enclosure (metal or metal-lined plastic).
Cable Types
| Cable type | Use |
|---|---|
| 6242Y (Twin & Earth) | Standard domestic circuits — lighting, sockets, ring mains |
| 6181Y (Singles) | Used in conduit — commercial and industrial |
| SWA (Steel Wire Armoured) | Buried external supply cables |
| 3-core & earth | Two-way switching, cooker circuits with separate switch |
Current cable colour coding:
- Live: Brown
- Neutral: Blue
- Earth: Green/Yellow
Old colours (pre-2006): Live = Red, Neutral = Black, Earth = Green. Identify carefully when working on existing installations.
Circuit Sizing
| Circuit | Typical cable size | Typical protection |
|---|---|---|
| Ring main (sockets) | 2.5mm² | 32A RCBO |
| Lighting | 1.0mm² or 1.5mm² | 6A or 10A RCBO |
| Cooker (up to 12kW) | 6mm² | 40A or 45A RCBO |
| Shower (8–10kW) | 6mm² or 10mm² | 40A or 45A RCBO |
| EV charger | 6mm² or 10mm² | 32A or 40A RCBO (Type A RCD) |
| Outdoor socket | 2.5mm² | 20A or 32A RCBO (Type A RCD) |
The Golden Rules
- Isolate before you work. Lock off or prove dead before touching any conductors.
- Test before you touch. Use a voltage indicator or multimeter to verify conductors are dead — do not assume.
- Test everything you've done before energising. Insulation resistance, continuity, polarity.
- Certify everything. Notifiable work must be certified. Minor works get a minor works certificate. New circuits or consumer units get an installation certificate.
- Leave it better than you found it. Note defects in existing installations. Do not add new ones.