Consumer Unit Upgrades in Sidcup: When Do You Need One?

A consumer unit — commonly called a fuse board or fuse box — is the central hub of your home's electrical installation. It houses the circuit breakers or fuses that protect each circuit, and the RCD or RCBO devices that provide earth fault protection. In many Sidcup homes, particularly those built or last rewired before 2000, the existing consumer unit may no longer meet current standards. This guide explains the different types of board, when an upgrade is needed and what the process involves.

Types of Consumer Unit Found in Sidcup Properties

Rewirable Fuse Boards

The oldest type still found in some Sidcup properties — a fuse board where a physical fuse wire is held in a ceramic fuse carrier. When a circuit overloads, the fuse wire melts and the circuit disconnects. These boards offer no RCD protection and should be upgraded. They are straightforward to identify: open the cover and you'll see ceramic fuse carriers rather than miniature circuit breakers.

Early MCB Consumer Units (No RCD)

A step up from rewirable boards, these use miniature circuit breakers (MCBs) that trip rather than blow, but have no RCD protection. More common in properties rewired in the 1980s. Again, no earth fault protection is provided.

Split-Load Consumer Units (Single or Dual RCD)

Introduced in the 1990s and widely installed until the mid-2010s. These boards use one or two RCDs to protect the circuits. The problem is that all circuits protected by one RCD will trip together if one circuit faults — so a problem with a socket circuit can trip out the fridge, freezer and boiler on the same side of the board. This type is still common in Sidcup rental properties and regularly appears as an EICR observation.

RCBO Boards (Current Standard)

Modern consumer units use an individual RCBO (Residual Current Breaker with Overcurrent protection) for each circuit. This provides both overcurrent and earth fault protection on a per-circuit basis. A fault on one circuit only trips that circuit, leaving everything else unaffected. This is the current standard for new installations and the type we install when carrying out upgrades.

When Do You Need a Consumer Unit Upgrade?

EICR Observation Requiring Upgrade

The most common reason for a consumer unit upgrade in Sidcup rental properties is an EICR observation. Where the existing board does not provide adequate protection — typically coded C2 — the report is Unsatisfactory and the landlord must carry out remedial works. A consumer unit upgrade is often the most practical way to address multiple EICR observations at once.

Old Rewirable Fuse Board

If your property still has a rewirable fuse board, an upgrade is strongly recommended regardless of whether an EICR has been carried out. These boards provide no earth fault protection and are increasingly difficult to maintain safely.

Nuisance Tripping from Split-Load Board

If you regularly lose power to multiple circuits because one circuit has tripped the shared RCD, an RCBO board eliminates this problem entirely by giving each circuit its own protection.

Not Enough Spaces

Extensions, outbuilding power supplies, EV chargers and additional circuits added over the years can fill up the available spaces on an older board. Rather than using sub-boards, it is usually better to replace the main board with a larger unit.

Property Sale or Remortgage

Surveyors and mortgage lenders increasingly flag outdated consumer units. Upgrading before listing a property for sale can avoid delays and renegotiation later in the process.

What's Involved in a Consumer Unit Upgrade in Sidcup?

A consumer unit upgrade typically takes between four and eight hours for a standard domestic property in Sidcup, depending on the number of circuits and the condition of the existing installation. The process involves:

• Confirming the existing circuits and their ratings
• Isolating the supply and disconnecting the old board safely
• Installing the new RCBO consumer unit in the same location or an agreed new position
• Reconnecting all circuits to the new board with correctly rated RCBOs
• Testing all circuits on the new board
• Correctly labelling all circuits
• Notifying the work under Part P of the Building Regulations
• Issuing an Electrical Installation Certificate on completion

The supply will need to be off for the duration of the work. We arrange the visit for a time that minimises disruption, and for rental properties we coordinate with tenants in advance.

Certification After a Consumer Unit Upgrade

All consumer unit upgrades are notifiable under Part P of the Building Regulations. We handle the notification to the relevant authority (typically via a registered scheme) and issue an Electrical Installation Certificate (EIC) on completion. For landlords, this certificate forms part of your property's electrical compliance documentation.