BS 7671 Plain English Guide 2026 — What the Regs Actually Say

BS 7671 is the British Standard for the Requirements for Electrical Installations. It's published by the IET in cooperation with BSI. Current edition is the 18th, published 2018, with Amendments 1, 2, 3 and 4 (April 2026).

It's not law. It's a standard. But the Electricity at Work Regulations 1989 (workplace) and the Building Regulations 2010 Part P (domestic) both reference BS 7671 as the means of compliance. Practically: if you don't follow BS 7671, you're in breach.

It covers installations from the supply point (DNO cut-out) inwards. It does not cover the DNO's network. It does cover everything in your fuse board, every circuit, every socket, every light fitting.

Part 1 — Scope, definitions. The dictionary.

Part 2 — Definitions in detail.

Part 3 — Assessment of general characteristics. Designing the installation.

Part 4 — Protection for safety. The big stuff — shock, thermal effects, overcurrent.

Part 5 — Selection and erection of equipment. The hardware section.

Part 6 — Inspection and testing. What every EICR engineer is doing.

Part 7 — Special installations and locations. Bathrooms, swimming pools, marinas, agricultural premises.

Most arguments on EICR coding land in Part 4, 5 or 7. Bathrooms (Part 7-701), EV chargers (Part 7-722) and PV (Part 7-712) are common reference points.

Type A RCD protection where DC fault current is foreseeable — covers modern domestic boards with induction hobs, EV chargers, certain LED drivers.

AFDD (arc fault detection) mandatory on socket circuits in HMOs, residential care, schools and other higher-risk premises. Recommended elsewhere.

SPD (surge protection device) expected at the main intake. Type 2 SPD adequate for most domestic. Type 1+2 for properties with lightning-prone overhead lines.

Updated bathroom zoning — minor changes to Zone 0/1/2 definitions for modern walk-in showers and wet rooms.

Updated EV charger installation requirements — every EV charger now needs Type B RCD or Type A + DC monitoring as default.

Reg 411.3.3 — RCD protection. Every socket in a domestic property must have 30 mA RCD protection. Lighting circuits not strictly required but recommended.

Reg 543.7 — earthing. Every metal extraneous conductive part (gas, water, structural steel) must be bonded to the main earthing terminal.

Reg 701 — bathrooms. Zone 0 (the bath), Zone 1 (above the bath up to 2.25m), Zone 2 (0.6m horizontal from zone 1). Different IP ratings and circuit requirements in each.

Reg 722 — EV chargers. Type A RCD minimum, with additional DC monitoring or Type B for Mode 3 (most home chargers).

Reg 134.1 — workmanship. Installations must be carried out by 'skilled persons'. Practically: NICEIC, NAPIT, or Stroma-registered.

They run insulation resistance, earth continuity, RCD trip-time, polarity and earth fault loop impedance tests against the Reg 6 thresholds.

They visually inspect every accessible fitting against the Part 5 selection requirements.

They code findings against the C1/C2/C3/FI scheme defined in the 18th Edition.

They don't memorise the whole document — they reference specific clauses for findings. A good engineer's report cites the BS 7671 clause for each C1 and C2 finding.

If your EICR report doesn't cite clauses for findings, ask. A vague 'lighting circuit has issues' without a Reg reference is a sign of a lazy or inexperienced engineer.

Reg numbers are XYZ.ABC where XYZ is the section and ABC is the specific clause. Reg 411.3.3 is Part 4, Section 411, Sub-section 3, Clause 3.

Part 7 specials use the 7XX numbering scheme. Reg 701.55 is bathrooms (Part 7-701), Section 55 (selection of wiring systems).

The IET publishes a free online BS 7671 quick reference — useful for landlords wanting to spot-check EICR findings without buying the £100+ book.

Practical landlord rule: trust your NICEIC contractor on coding decisions. The book is dense and ambiguous in places. A 5-minute conversation with the engineer usually clarifies any disputed code.