Consumer Unit Upgrade: When You Need One and What to Expect

Your consumer unit — commonly called a fuse box or fuse board — is the single most important safety device in your home's electrical system. It houses the circuit breakers and residual current devices that protect every circuit in your property. If it is outdated, the entire protection system is compromised.

When Does a Consumer Unit Need Upgrading?

• It has rewirable fuses (ceramic holders with visible wire)
• It is in a plastic (non-metal) enclosure
• It has no RCD protection
• It was installed before 2016
• It has been flagged as unsatisfactory in an EICR
• You are adding new circuits (extension, EV charger, garden room)
• You are selling or letting the property

Why Metal-Clad Consumer Units Are Now Required

Since January 2016, all new and replacement consumer units in domestic properties must be housed in a metal (non-combustible) enclosure. This regulation — BS 7671 Regulation 421.1.201 — was introduced because plastic consumer units can melt and ignite during an internal arc fault, potentially spreading fire to surrounding building materials. Metal enclosures contain any internal arcing safely.

RCD vs RCBO: Which Should You Choose?

A split-load RCD board groups circuits under two 63A RCDs. A fault on any circuit trips all circuits in that group. An RCBO board gives each circuit its own individual protection — a fault on one circuit affects only that circuit. RCBO boards cost £100–£200 more but provide significantly better discrimination, which is particularly valuable if you work from home, have medical equipment, or run a home server.

What Does a Consumer Unit Upgrade Cost?

• Split-load RCD board: £450 – £600
• Full RCBO board: £600 – £750
• Additional surge protection (SPD): included as standard
• Full testing of all existing circuits: included
• Electrical Installation Certificate: included

What Happens During the Installation?

A consumer unit upgrade is typically completed in a single working day. The power is off for approximately 4–6 hours during the changeover. We isolate the supply, remove the old board, install the new metal-clad consumer unit, reconnect all circuits, test every circuit comprehensively, and issue your certificate. Your home is fully operational by the end of the day.

A consumer unit upgrade is one of the fastest, most cost-effective safety improvements you can make. It takes one day, costs a fraction of a rewire, and brings your entire protection system up to current standards.