Consumer Unit Wiring
Regulations Explained
A plain English breakdown of the BS 7671 sections that govern UK consumer units in 2026. Enclosure rules, protection requirements, identification standards plus the certification chain a homeowner should expect from any compliant install.
UK consumer units must comply with BS 7671:2018+A2:2022 (the 18th Edition Wiring Regulations, Amendment 2). The key sections that apply are Section 132 (design), Section 411 (protective measures against electric shock), Section 421 (protection against fire including AFDD requirements), Section 514 (identification plus labelling) plus Section 530 onwards (selection of devices). The enclosure must be non-combustible (metal). Every install is notifiable under Part P of the Building Regulations plus must produce an Electrical Installation Certificate plus a Building Control notice.
Four figures
worth knowing
These four references frame every compliant UK consumer unit install in 2026.
7671
The Standard
The IET Wiring Regulations published by BSI. The single source document every UK electrician works to on a domestic install.
Amendment 2
The current published amendment. Strengthens AFDD requirements plus surge protection guidance across domestic installs.
Notifiable Work
Building Regulations Part P. Consumer unit replacement is always notifiable. Self-certification only available to registered electricians.
Edition
Current Edition
Published 2018. Amended 2020 (Amendment 1) plus 2022 (Amendment 2). The 19th Edition is in industry consultation.
Four sections that
govern every install
BS 7671 is a thick book. For a consumer unit specifically, four broad regulatory areas matter. Every compliant install must satisfy all four.
Enclosure
Non-combustible enclosure required since 2016. Section 421.1.201 sets the rule. In practice this means a steel or GRP-reinforced fire-resistant case.
Protection
RCD additional protection on most circuits per Section 411.3.3. AFDD requirements on certain premises per Section 421.1.7. Overcurrent on every circuit.
Identification
Every circuit must be labelled clearly per Section 514. The board must carry a maintenance plus operating diagram. Devices must be RCD-test labelled.
Certification
EIC issued per Part 6 of BS 7671. Building Control notification through a Part P scheme (NICEIC, NAPIT, Stroma, ELECSA) within 30 days.
The BS 7671 sections that touch a consumer unit install
BS 7671 runs to over 600 pages. A homeowner does not need to read it. The job of any registered electrician is to translate the relevant sections into a compliant install. The sections below are the ones that matter most when planning, fitting or assessing a UK consumer unit.
Section 132: Design
Section 132 sets out the broad design principles every electrical installation must meet. For a consumer unit this means the design must consider maximum demand, the type of supply earthing arrangement (TN-S, TN-C-S or TT), the prospective fault current at the origin plus the layout of final circuits. This is why a registered electrician carries out a design before quoting. A board fitted without that calculation may not handle the actual household load correctly.
Section 411: Protection against electric shock
Section 411 is the largest single section that governs consumer unit protection. The two clauses that homeowners encounter directly are:
- 411.3.3 requires additional protection by 30mA RCD on socket outlets rated up to 32A intended for use by ordinary persons, plus on cables concealed in walls or partitions to a depth less than 50mm.
- 411.3.4 requires additional protection by 30mA RCD on socket outlets in dwellings (added in Amendment 2 of the 18th Edition).
Together these clauses are why every modern UK consumer unit ships with RCD or RCBO protection on most circuits. A board with no RCD protection is non-compliant on a new install plus will normally fail an EICR.
Section 421: Protection against fire
Section 421 covers protection against thermal effects plus is where the metal enclosure rule plus the AFDD requirements live:
- 421.1.201 requires consumer units in domestic premises to have an enclosure made from non-combustible material (or have non-combustible material around the enclosure). Introduced in Amendment 3 to the 17th Edition (January 2016). This is the rule that ended new plastic consumer unit installs.
- 421.1.7 covers Arc Fault Detection Devices. AFDDs are required on socket circuits in higher-risk residential buildings (HRRBs), HMOs, care homes plus purpose-built student accommodation. Recommended elsewhere.
Section 514: Identification plus labelling
Section 514 is the section most often missed on poor-quality installs. It requires every protective device to be labelled with the circuit it protects, the rating of the device plus any RCD test instruction. The board must also carry a clear circuit chart or diagram that lets a future electrician (or homeowner) understand which device controls which circuit. A board with no labelling fails Section 514 even if everything else is perfect.
Section 530 onwards: Device selection
Section 530 onwards covers selection of devices. For a consumer unit this means the right type of RCD (Type AC, A, F or B depending on connected loads), the right MCB curve (B or C for most domestic), the right RCBO sensitivity, the right SPD class plus the right AFDD compatibility with the rest of the board.
This is also where device manufacturer compatibility matters. BS 7671 plus the IET on-site guidance both confirm that consumer units should be assembled using devices compatible with the manufacturer's enclosure type-test certificate. Mixing brands voids the type test plus is a non-compliance unless the enclosure manufacturer has explicitly approved the mix.
Part P of the Building Regulations
BS 7671 is the wiring standard. Part P of the Building Regulations is the legal mechanism that enforces it on domestic installations in England plus Wales. Part P makes consumer unit replacement notifiable work. Notification can be done in one of two ways:
- Self-certification by a registered electrician through their certification scheme (NICEIC, NAPIT, Stroma or ELECSA). The certificate plus Building Control notice are issued by the scheme on behalf of the local authority.
- Direct notification to Building Control by a non-registered electrician. The local authority then sends an inspector. This route is rarely used because it is slower plus more expensive.
Either route ends with a Building Control compliance certificate. That document plus the EIC together form the paperwork chain a future buyer's solicitor will ask to see.
Compliant install
cost bands
Every band below assumes full BS 7671 compliance, EIC issuance plus Building Control notification through a Part P scheme.
BS 7671 Compliant Consumer Unit Cost Bands
Prices include parts, labour, EIC certification plus Building Control notification through a Part P scheme. Remedial work uncovered during testing is quoted separately.
Four regulatory
milestones
UK consumer unit regulations have moved through four major moments. Each one shaped what compliance looks like today.
17th Edition Adopted
RCD additional protection required on most domestic circuits. Triggered the move from MCB-only boards to dual RCD plus full RCBO designs.
Amendment 3 Metal Mandate
Section 421.1.201 introduced. Plastic consumer units no longer compliant on new domestic installs. Steel becomes the default enclosure.
18th Edition Published
BS 7671:2018 published. AFDDs introduced as a recommendation. Surge protection guidance strengthened. Cable management rules expanded.
Amendment 2
BS 7671:2018+A2:2022 published. AFDDs mandatory on socket circuits in HRRBs, HMOs plus care homes. Prosumer (solar/battery) integration clarified.
Four things to verify on
any compliant install
Confirm the certification scheme
Ask the electrician which scheme they belong to (NICEIC, NAPIT, Stroma or ELECSA). Verify the membership number on the scheme website before booking.
Get the EIC plus Building Control notice
Both documents must be issued. The EIC arrives on the day. The Building Control notice arrives within 30 days through the certification scheme.
Check the circuit labelling
Section 514 requires clear labelling on every circuit. If your new board has no chart or unlabelled MCBs, the install is technically non-compliant.
Keep all paperwork with the deeds
Your EIC plus Building Control notice belong with the property pack permanently. Buyers, solicitors plus future EICR engineers will all ask for them.
Consumer Unit Upgrades in Milton Keynes
C-Lec Electrical fits new metal RCBO consumer units to BS 7671:2018+A2:2022 across Milton Keynes, Bedford plus the surrounding Bedfordshire area. Every install certified, notified to Building Control plus paper-trail complete on handover.
Compliant install vs
shortcut install
A compliant BS 7671 install plus a corner-cutting cash-in-hand install both end with a working consumer unit. They produce very different paper trails.
Registered electrician install
- ✓EIC issued on the day with full test results plus device schedule.
- ✓Building Control notice issued within 30 days through Part P scheme.
- ✓Designed to Section 132 with maximum demand plus fault current calculated.
- ✓RCD protection across all required circuits per Section 411.
- ✓Survives EICR plus property sale survey with no comments against the install.
Cash-in-hand without certification
- ✗No EIC means no proof of compliant test results.
- ✗No Building Control notice creates a Part P breach that cannot be retrospectively fixed cheaply.
- ✗Likely EICR fail on next inspection if labelling, RCD selection or earthing checks fail.
- ✗Insurance risk on any future electrical-related claim.
- ✗Property sale problem when the buyer's solicitor asks for paperwork that does not exist.
For the wider context on consumer unit types, RCDs, AFDDs plus the practical decisions homeowners face, head back to our full guide to consumer units where every common homeowner question is answered in one place.
Back to the Consumer Units Guide
This article sits inside our complete Consumer Units knowledge base. The hub covers everything from board types plus RCBOs through to landlord requirements plus BS 7671 wiring regulations.
More on consumer
unit standards
If you are still nailing down the basics of what a consumer unit actually is, the explainer on what is a consumer unit covers every part of the box in plain English. To understand the specific enclosure rule that ended new plastic installs, our deep dive on metal consumer unit requirements walks through Section 421.1.201 plus what compliant materials look like. To read more on the legal status of RCD protection on UK domestic circuits, see are RCDs legally required for the full Section 411 picture. If you need a fully compliant board fitted in Milton Keynes or Bedford, our consumer unit upgrades service page is the fastest route to a quote.