Fuse Board Upgrade Cost in London: What to Expect in 2026

Why Fuse Boards Need Replacing

The fuse board — now more accurately called a consumer unit — is the central point of electrical protection in a property. Older properties in London were originally fitted with rewirable fuse boards, where each circuit is protected by a porcelain or plastic fuse carrier holding a length of fuse wire. When a fault occurs, the fuse wire melts to interrupt the circuit. These installations were standard up to the 1960s and 1970s and are still found in a significant proportion of older London properties. While not inherently unsafe if they are in good condition and correctly fused, rewirable boards offer no residual current device (RCD) protection, which means that a fault involving earth leakage that could cause electrocution may not be interrupted before serious injury occurs.

Modern consumer units contain miniature circuit breakers (MCBs) instead of fuse carriers, and RCD protection — either as combined RCBO devices on each circuit or as whole-board RCD protection. The 18th Edition of BS 7671, which has been the standard for electrical installations in the UK since 2019, requires that most new circuits and rewired circuits are protected by an RCD. An EICR inspection of a property with an old rewirable board will almost always identify C2 observations relating to the absence of RCD protection, resulting in an unsatisfactory overall result that requires a consumer unit replacement to resolve.

What a Consumer Unit Replacement Involves

A full consumer unit replacement in a London property involves isolating the supply at the meter, removing the old board, installing a new consumer unit with MCBs and RCD protection configured to protect all circuits, reconnecting all circuit cables to the new board, and testing each circuit to confirm safe operation. The work also typically involves checking and upgrading the main earthing and bonding arrangements, since older properties frequently have inadequate earthing that must be brought up to current standards as part of the installation. The electrician will complete a minor works certificate or full electrical installation certificate on completion, which must be registered with a competent person scheme if the electrician is a registered member.

The work typically takes between four and eight hours depending on the number of circuits and the condition of existing earthing and bonding. The supply will be off for most or all of this period, which should be factored in for occupied properties — tenants and occupants should be informed in advance.

Consumer Unit Replacement Costs in London

For a one or two-bedroom flat in London with eight to twelve circuits, a consumer unit replacement typically costs between 400 and 650 pounds in 2026, including the consumer unit, all associated materials, and labour. For a three-bedroom house with twelve to sixteen circuits, the cost rises to approximately 550 to 800 pounds. For a four or five bedroom house with sixteen or more circuits, costs range from 700 to 1,100 pounds or more depending on complexity.

These figures assume that the cable condition is reasonable and that no rewiring of individual circuits is required. If the electrician identifies damaged, deteriorated, or incorrectly sized cables during the board replacement, rewiring of those circuits adds to the overall cost. Properties requiring a significant earthing upgrade — for example, where the incoming main earth conductor is undersized or the main bonding to gas and water services has never been installed — may also incur additional cost for earthing and bonding materials and labour.

When to Upgrade Without an EICR Requiring It

Some property owners choose to replace an old rewirable fuse board proactively rather than waiting for an EICR to mandate it. Circumstances where proactive replacement makes sense include: when a property is being prepared for sale and the existing board is likely to be flagged by a buyer survey or mortgage valuation; when a significant electrical extension or alteration is planned and the existing board cannot accommodate additional circuits; when the property is being re-let after a void period and the landlord wants to ensure the installation meets current standards; or when the existing board has already tripped or failed in a way that suggests it is nearing end of life. Prestige Engineers carry out consumer unit replacements across all London boroughs, with all work registered with a competent person scheme and full certification provided on completion.