Most homeowners know where their consumer unit is. Far fewer know whether it actually protects them. An RCD — Residual Current Device — is the component that makes the difference between a fault that trips a circuit and one that causes a serious electric shock or fire. If your consumer unit was installed before the 2008 wiring regulations, there is a good chance it has none.

What is an RCD and how does it work?

An RCD continuously monitors the balance of current flowing out through the live conductor and returning through the neutral. Under normal conditions, these values are equal. When a fault occurs — a person touching a live conductor, a cable damaged inside a wall, moisture entering a fitting — some current flows to earth instead of returning via neutral. The imbalance is detected by the RCD, which trips the circuit in approximately 30–40 milliseconds: fast enough to prevent a lethal shock and fast enough to interrupt the arc before it can ignite surrounding material.

A standard MCB (Miniature Circuit Breaker) provides overcurrent protection — it trips when too much current flows through the circuit. It does not detect earth leakage faults. An RCD provides earth fault protection. The two devices serve different functions and both are required in a modern installation.

1

Fault occurs

Current leaks to earth — through a person, damaged insulation, or moisture — instead of returning via the neutral conductor.

2

30ms

RCD detects imbalance

The RCD measures the difference between live and neutral current. A fault current as small as 30mA triggers the trip mechanism.

3

Circuit isolated

Power to the affected circuit is cut before the fault current can cause cardiac arrest or ignite surrounding material.

Signs your consumer unit may need attention

Not every consumer unit that needs upgrading shows obvious faults. Some of the strongest indicators are structural rather than symptomatic.

• Frequent tripping after plugging in appliances — particularly on socket circuits, suggests either an overloaded circuit or a faulty appliance generating earth leakage; an RCD will detect the latter where an MCB cannot

• Burning smells, buzzing sounds, or heat near the consumer unit — arcing or loose connections inside the unit itself; do not wait for a periodic inspection to address these

• Rewirable ceramic fuse carriers — if you can pull out a fuse holder and see a strand of wire, your board has no MCB overcurrent protection and almost certainly no RCDs

• A single large RCD covering all circuits — older split-load boards with one RCD per side mean any earth fault on any circuit trips everything on that half of the board; RCBOs on individual circuits prevent this

• Recent additions that changed your load — EV chargers, electric showers, new kitchen appliances, and extensions all add load that an older board may not have been designed to handle

• No record of when the board was installed or last inspected — if the answer is "it came with the house," it warrants an EICR before assuming it is adequate

Test your RCDs now

Every RCD has a test button marked "T". Press it: the RCD should trip immediately. If it does not trip, the device has failed and is providing no protection. Reset and press again monthly. If the test button is stiff, stuck, or produces no response, the consumer unit needs inspection — a failed RCD is not better than no RCD; it is worse, because it creates a false impression of protection.

Landlords: compliance, fewer call-outs, and documented protection

Private landlords in England have been legally required to carry out EICR inspections at least every five years since the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 came into force. Consumer unit condition and RCD provision are among the most commonly cited items on EICR reports.

The practical implications of an inadequate consumer unit in a rental property:

• C2 or C1 codes on the EICR — absence of RCD protection on socket circuits is typically coded C2 (potential danger); a rewirable fuse board or a board with an inoperative RCD may be coded C1 (danger present). Both require remedial work within the statutory timeframe before the report can be accepted by a local authority

• 28-day remediation deadline for C2 codes — landlords must complete C2 remedial work and provide evidence to the local authority within 28 days of receiving the report; failure to do so can result in civil penalties

• Reduced emergency call-outs — a board with individual RCBOs per circuit means a fault on one circuit does not take out half the property; tenants are less likely to call out of hours because the kitchen lost power when a hairdryer tripped a shared RCD

• Documented protection — an upgraded consumer unit, correctly certified and with a completion certificate lodged under Part P, is evidence of compliance and due diligence; it is relevant if a claim is ever made against the landlord regarding electrical safety

What the EICR remedial process looks like

After an EICR with C1 or C2 codes, Volt provides a fixed-price quote for remedial work. For most consumer unit upgrades, the work takes one day. We carry out the installation, test all circuits against BS 7671, issue a BS 7671 Electrical Installation Certificate, and notify the work to the local authority under Part P. You receive all documentation required to satisfy your legal obligation and, where applicable, to update your landlord's insurance records.

Homeowners: what the upgrade delivers

For owner-occupiers, a consumer unit upgrade is not typically urgent in the way a gas leak or structural fault is — but it is the type of improvement that compounds in value over time, particularly as electrical loads in homes increase and as the building materials and insulation of older properties continue to age around older wiring.

The upgrade makes sense if

You are planning any of the following

• A kitchen or bathroom renovation where circuits are being modified

• Installing an EV charger or electric shower on a new dedicated circuit

• Adding outdoor sockets, garden lighting, or outbuilding electrics

• Fitting solar PV or battery storage connected to the board

• Selling the property — an updated board removes a common buyer concern and potential survey issue

The upgrade is overdue if

Your current board has any of these

• Rewirable ceramic fuse carriers (any age)

• No RCD protection visible on any circuit

• A single RCD covering all socket circuits together

• Signs of heat discolouration, arcing marks, or loose covers

• No BS 7671 Installation Certificate associated with the board

The cost of a consumer unit upgrade in a typical UK home is modest relative to the value of the protection it provides. The installation takes one day. Every circuit is tested before the board goes back into service. The work is notified to the local authority under Part P and a completion certificate is issued — giving you a permanent record of the installation and its compliance with the current edition of BS 7671.

Protection that works. Book a consumer unit assessment.

Volt Electrical Solutions installs and upgrades consumer units across London and Essex. NICEIC approved, Part P certified, 1-year workmanship guarantee. We carry out EICRs and same-day remedial work for landlords.

Call 07984 919 757 or book a free estimate online.