Safety Regulations

Consumer Unit Upgrades: What the 2024–25 Wiring Regulation Changes Mean for Homeowners

Amendment 3 to BS 7671 (the IET Wiring Regulations) brought significant changes to the requirements for consumer unit (fuse board) replacements and new circuits — including stronger rules on surge protection and RCD coverage that apply to all installations carried out in England, Scotland and Wales.

What is BS 7671 Amendment 3?

BS 7671 is the national standard for electrical wiring in the UK. Amendment 3, which became effective during 2024–25, updated several key requirements — particularly around consumer unit replacements, the addition of new circuits, and protection devices. All electrical work carried out by a registered electrician must comply with the current edition of BS 7671.

Key change 1: Surge Protection Devices (SPDs) now more widely required

SPDs protect connected equipment from voltage spikes caused by lightning or switching events on the network. Under the updated regulations, SPDs are now required in a greater number of scenarios — particularly where the loss of equipment would cause serious consequences (medical equipment, fire alarm systems, sensitive electronics). A formal risk assessment is required to document any decision to omit an SPD.

Key change 2: RCD protection requirements tightened

RCDs (Residual Current Devices) protect against electric shock and fire caused by earth faults. The regulations now require additional protection by 30mA RCDs on a wider range of final circuits — particularly socket outlets, lighting circuits and outdoor supplies. A consumer unit replacement in 2025 or 2026 must meet these requirements for any circuits that are being added or altered.

When do I need to replace my consumer unit?

You're not legally required to replace a consumer unit simply because it predates the latest regulations — provided it passes an EICR. However, replacement is typically required when:

• An EICR records C1 or C2 observations on the board itself
• You are adding new circuits (e.g. EV charger, extension, garden room)
• There is visible damage, signs of overheating or insulation deterioration
• The board contains rewirable fuses rather than MCBs

Does replacing a consumer unit require Building Regulations notification?

Yes. Consumer unit replacement is notifiable work under Part P of the Building Regulations. It must be carried out by a Part P-registered electrician (who self-certifies), or pre-notified to your local building control office. You should receive an Electrical Installation Certificate and a Building Regulations Compliance Certificate on completion.

What does a consumer unit upgrade typically cost in 2026?

Industry figures for 2025 put the average cost at around £1,000, with a range of approximately £600–£1,800 depending on property size, number of circuits and whether any remedial work is required on existing wiring.