Consumer Unit Upgrade in London — When You Need One and What It Costs
Old fuse boxes and metal consumer units are increasingly flagged on EICRs as requiring replacement. This guide explains when a consumer unit upgrade is necessary, what the new unit provides, and typical London costs.
When Is a Consumer Unit Upgrade Required?
Consumer unit (fuse box) upgrades are one of the most common remedial actions arising from EICR inspections of older London properties. Specific triggers include:
- Old-style rewireable fuse box: Ceramic fuse holders with rewireable fuse wire provide no RCD protection and no earth fault detection. These are typically coded C2 (potentially dangerous) on an EICR, requiring upgrading within 28 days for rented properties.
- Plastic consumer unit without RCD protection: Consumer units without residual current device protection on all circuits have been non-compliant with wiring regulations since 2008. These are typically coded C2.
- Consumer unit in a bathroom or kitchen: Consumer units installed in bathrooms or kitchens are prohibited under current regulations. They must be relocated.
- Damaged or overloaded consumer unit: Physical damage, signs of overheating, or circuits running at excessive load are C1 (immediate danger) or C2.
What a New Consumer Unit Provides
Modern consumer units (RCBO boards) offer:
- RCD protection on all circuits: A residual current device detects earth faults (including the path through a person) and trips in 30 milliseconds — preventing electrocution from faulty appliances
- RCBO (Combined MCB + RCD) per circuit: Individual circuit protection means one fault trips only that circuit — not the entire board as with older split-load units
- Surge protection device (SPD): Now required under 18th Edition wiring regulations for new installations and consumer unit replacements in most circumstances
Consumer Unit Replacement Cost in London 2025
- Standard consumer unit replacement (same location, same number of circuits): £350-600 including all labour and an Electrical Installation Certificate
- Consumer unit replacement plus relocating unit: £500-900 depending on the new location and cable routing
- Consumer unit upgrade on an older property requiring cable upgrades to some circuits: £700-1,500 if older aluminium wiring or deteriorated cables need partial replacement
Process and Building Regulations
Consumer unit replacement is a notifiable electrical installation work under Building Regulations Part P. The electrician carrying out the work must either be a registered competent person (NICEIC, NAPIT, Stroma registration) who self-certifies the work, or the work must be inspected and certified by a third-party competent person. You must receive an Electrical Installation Certificate (EIC) on completion — retain this for the property file.
Frequently asked questions
How long does a consumer unit replacement take?
A straightforward like-for-like consumer unit replacement in a standard London house or flat takes 4-6 hours for a competent electrician. The supply to the property must be isolated during the work — this means a planned power outage for the duration. New consumer unit plus testing and certification: one working day.
Does replacing a consumer unit require an EICR?
A new consumer unit triggers issuance of an Electrical Installation Certificate (EIC) for the specific work done — it is not a full EICR of the whole installation. However, if an existing EICR is recent and the board replacement is the only outstanding remedial action, the EIC satisfies the EICR remedial requirement. If no recent EICR exists, it's prudent to do both together.
What is an RCBO consumer unit and is it worth it?
An RCBO consumer unit has a separate RCBO (combined MCB + RCD) for each circuit, unlike a split-load board which groups circuits onto shared RCDs. The benefit: one faulty circuit trips only that circuit, not half the house. For HMOs and rental properties, this significantly reduces tenant complaints from unrelated circuit trips. Worth the modest additional cost (£50-100 more than split-load).
Can I still sell or rent a property with an old fuse box in London?
You can sell, but an old rewireable fuse box will likely be flagged on a buyer's survey and mortgage valuation. For renting, an EICR will code an old rewireable fuse box C2 (potentially dangerous), which requires remedying within 28 days for rented properties under the Electrical Safety Standards Regulations 2020.