Do I Need a New Consumer Unit?

The consumer unit is the heart of your home's electrics. It splits the supply into circuits and contains the devices that switch them off when something goes wrong. Many homes have boards that are perfectly serviceable; others are running on equipment that would not be fitted today. This guide explains what to look for and when an upgrade is advised.

Rewireable fuses or circuit breakers?

The oldest boards use rewireable fuses: ceramic carriers with a length of fuse wire. They work, but they are slow to react, easy to rewire with the wrong size wire and give no protection against electric shock. Later boards use miniature circuit breakers, MCBs, small switches that trip on overload or short circuit and can be reset. If your board has fuse carriers, an upgrade is usually recommended.

RCD protection

An RCD, residual current device, detects current leaking to earth, for example through a person touching a live part, and switches off very quickly. It is one of the most important safety devices in a home. Many older boards have no RCD at all. Others, from the 2000s and early 2010s, have one or two RCDs each covering a group of circuits, so a single fault can switch off half the house.

RCBOs

An RCBO combines an MCB and an RCD in one device, protecting each circuit individually. A fault on the kitchen sockets then switches off only that circuit, leaving lights and the freezer running. Many new boards are built with RCBOs throughout; our guide to consumer unit upgrade costs explains how the layout affects the price.

Non-combustible enclosures

Current guidance for consumer units in homes calls for enclosures made of non-combustible material, usually metal, following concerns about fires spreading from plastic units. New boards are therefore normally metal. An existing plastic board in good condition doesn't automatically have to be replaced for that reason alone; it is one factor considered alongside the protection it offers.

Surge protection

Surge protective devices help protect the installation and connected equipment from voltage spikes, for example from lightning strikes on the network. Current regulations call for them in many new installations, and they are commonly included when a board is replaced.

Signs a board needs attention

Buzzing, crackling, heat, a burning smell or scorch marks around the board mean switch off at the main switch if safe and call; see our guide to a buzzing fuse box. A cracked or damaged case, missing blanks leaving openings, or devices that won't reset are other reasons to have it checked.

When an upgrade is advised

An upgrade is commonly advised when the board has rewireable fuses, lacks RCD protection, is damaged, has no space for a new circuit you need, such as for an EV charger or electric shower, or when an EICR recommends it. A rewire or major extension is also a natural point to replace the board.

When it isn't needed

A board with MCBs and suitable RCD protection, in good condition and with adequate capacity, may not need changing at all. If someone recommends replacement, ask them to explain why in terms of the protection it provides and what testing showed. An EICR gives an independent picture of the whole installation.

Why does my consumer unit keep tripping?

Repeated tripping is usually caused by a fault on a circuit or appliance rather than the board. Replacing a board won't cure that fault and may even make it more obvious. Our guide to why the RCD keeps tripping explains the safe checks.

Testing comes first

Before a new board is connected, the existing circuits are tested. Faults hidden by an old fuse box can show up as soon as RCD protection is added, and they need fixing before the job is finished. A good quote explains how that will be handled.

Where the board is

Consumer units are usually under the stairs, in a hall cupboard, in the garage or by the front door. Moving one to a new position is possible but adds work, because the meter tails and every circuit have to be extended to reach it. If you are renovating and the current location is awkward, mention it at the quote.