Why Lack of RCD Protection Can Sometimes Fail an EICR

What Is an RCD?

A residual current device (RCD) detects imbalances between the live and neutral conductors in a circuit — the kind of imbalance that occurs when current is taking an unintended path, such as through a person. When it detects this, it trips the circuit within milliseconds.

RCDs provide a level of protection that fuses and standard circuit breakers do not. A standard MCB (miniature circuit breaker) protects against overloads and short circuits. An RCD protects against earth faults and electric shock. The two work differently and provide different types of protection.

Why Not Having an RCD Isn't Always a C2

The current edition of BS7671 (the wiring regulations) requires RCD protection for a wide range of circuit types and locations. But it is important to understand that older installations were built to the regulations that applied when they were installed. An installation that was wired to BS7671 16th Edition or earlier may not have full RCD coverage, and that alone does not necessarily make it dangerous.

Where the absence of RCD protection is on circuits that do not serve high-risk locations, an inspector may record it as a C3 — an improvement recommended — rather than C2. This is a judgement call based on the type of circuit, the location it serves, and the risk that exists without the protection.

Where Lack of RCD Protection Is More Likely to Be Coded C2

There are specific locations and circuit types where the absence of RCD protection is more likely to be coded C2 — potentially dangerous — because the risk of electric shock or fire is significantly higher.

• Socket outlets — particularly those likely to supply portable equipment used outdoors
• Bathroom and shower circuits, where the presence of water significantly increases shock risk
• Kitchen circuits close to sinks or water-using appliances
• Circuits supplying garden or outdoor equipment
• Circuits in locations where the installation is particularly old or the wiring condition is deteriorated
• Circuits in zones of increased shock risk as defined by BS7671

The Bathroom Circuit Example

A bathroom is classified as a 'special location' under the wiring regulations, divided into zones based on proximity to water. Circuits entering bathroom zones require specific types of protective measures. Where a bathroom circuit — such as a shower unit, extractor fan, or shaver socket — is fed without RCD protection, an inspector is very likely to code this as C2, because the combination of water and electricity in an enclosed space represents a significant shock risk.

This is one of the most common C2 observations on older properties. The cost of adding RCD protection to a bathroom circuit is typically modest, and it is one of the remedial works most worth carrying out promptly.

Socket Outlets and Outdoor Equipment

The regulations require that socket outlets in most domestic and residential locations are protected by a 30mA RCD, specifically because of the risk of portable equipment being used outdoors or near water. A socket outlet that someone could plug an extension lead into and carry outside — regardless of whether they actually do this — is considered a risk.

Again, on older installations, this may be coded C2 where there are socket circuits that could present this risk and have no RCD protection. On a simple installation where all socket circuits are clearly only for internal use and the installation is otherwise in good condition, an inspector may apply a C3. The coding will reflect the specific risk at the specific property.

What to Do If You Receive This Observation

If your EICR records lack of RCD protection as a C2, your report will be Unsatisfactory and you will need to arrange remedial works. Adding RCD protection does not always mean replacing the consumer unit. Depending on the board design, it may be possible to add a plug-in RCD adapter at the socket level, install an inline RCD unit, or split a circuit at the board to add RCD coverage. Your electrician will advise on the most appropriate approach.

If it is coded C3, there is no obligation to act within a specific timeframe — but adding RCD protection where it is absent is always a worthwhile investment in the safety of the installation and the people using it.