Consumer Unit (Fuse Box) Replacement: Cost and When You Need One

The consumer unit — still often called a fuse box, though that's the older terminology — is the central point where electricity entering your home is split into individual circuits, each protected against faults. It's one of the most common single items flagged on an Electrical Installation Condition Report, particularly in older homes that haven't been updated in some time.

What an old-style fuse box actually looks like

Older fuse boxes typically use rewireable fuse wire or simple cartridge fuses, housed in a box that often shows visible wear — cracked casing, scorch marks around individual fuse holders, or a mix of circuit ages bolted on over the years as the house was extended or rewired piecemeal. A modern consumer unit, by contrast, uses moulded-case circuit breakers (and usually RCD or RCBO protection — see the FAQ below) in a single, clearly labelled enclosure.

Why old fuse boxes get flagged

The main difference between an old-style fuse box and a modern consumer unit is RCD (residual current device) protection — a safety feature that rapidly cuts power if it detects current leaking to earth, which is what protects against electric shock in a fault condition. Many older fuse boxes predate this requirement, or only partially cover the circuits in the house, which is why an EICR (see our EICR guide) so often flags it as a priority remedial item.

What a consumer unit replacement involves, step by step

• Removing the old fuse box or consumer unit
• Installing a new consumer unit with appropriate RCD or RCBO protection across all circuits
• Reconnecting and testing each circuit individually as it's brought back online
• Labelling the new unit clearly, which is a requirement, not just good practice
• Issuing an electrical certificate for the completed work

Preparing for the day

• Expect the power to be off for part of the day — confirm the likely window with your electrician in advance.
• Anything relying on continuous power (a chest freezer, medical equipment, a home office needing uninterrupted internet) is worth flagging beforehand.
• Clear physical access to the consumer unit itself, which is sometimes in a cupboard used for storage.
• Ask whether any sockets or circuits will be tested in a way that requires appliances unplugged first.

Roughly what it costs

As a general guide only, a straightforward consumer unit replacement is a relatively contained job compared to a full rewire — usually completed in a day — though the exact cost depends on the number of circuits, the accessibility of the existing installation, and whether any additional remedial work is bundled in at the same time. It's genuinely one of the more cost-effective electrical safety upgrades relative to the improvement it makes, which is part of why it's such a common standalone recommendation.

When it's paired with wider work

A consumer unit replacement is very often carried out alongside a full or partial rewire, since both involve similar access and testing work — see our guide on rewiring costs if an EICR or general assessment has suggested wider electrical work may be needed, not just the consumer unit itself.

Choosing an electrician

As with any electrical work in a dwelling, this falls under Part P of the building regulations and should be carried out by a registered competent-person scheme electrician, or otherwise notified to building control. Ask to see registration before booking the work, and ask specifically whether the quoted price includes testing, certification and labelling — not just the physical swap.