Common C2 Defects Found During EICRs and Repair Guidance

Why C2 Codes Are So Common

C2 (potentially dangerous) is the most common classification code on unsatisfactory EICRs. Unlike C1 codes which are immediate emergencies, C2 codes represent conditions that could become hazardous under certain circumstances. They are often caused by standards evolving faster than installations age — what was compliant 15 years ago may not meet today's BS 7671 requirements.

This guide covers the six most common C2 codes we encounter during inspections across Manchester and Stockport, with real-world causes, typical remedial costs, and how to prevent them in future.

1. Absence of RCD Protection on Socket Circuits

This is the single most common C2 code we see. Properties built before 2008 often lack RCD (Residual Current Device) protection on socket outlet circuits. While these installations were compliant when installed, Amendment 2 to BS 7671 now mandates RCD protection on all socket circuits up to 32A.

• Cause: Consumer unit installed before 2008 without RCDs, or older unit with only partial RCD coverage
• Risk: Electric shock from faulty appliances or damaged cables, particularly in bathrooms and kitchens
• Remedy: Install RCD protection either by adding an RCD to the existing consumer unit or upgrading to a modern RCBO board
• Typical remedial work: RCD addition or consumer unit replacement
• Prevention: Ensure any future electrical work includes RCD assessment

2. Plastic Consumer Unit Without Fire Barriers

Amendment 2 (2022) requires consumer units to be constructed from non-combustible material or have fire-resistant barriers between compartments. Plastic units installed before this requirement are now flagged as C2.

• Cause: Pre-2022 plastic consumer units (common in pre-2016 installations)
• Risk: Fire can spread between compartments, potentially engulfing the entire board
• Remedy: Replace with a modern metal-clad consumer unit with fire barriers
• Typical remedial work: consumer unit replacement including full circuit testing and certification
• Prevention: When carrying out any electrical work, ask the electrician to assess the consumer unit condition

3. Inadequate Earthing or High Earth Resistance

Proper earthing is fundamental to electrical safety. High earth electrode resistance or missing earth bonding creates a shock hazard if a fault occurs. This is more common in older properties with original earthing systems.

• Cause: Corroded earth electrode, loose earth connections, missing supplementary bonding
• Risk: Fault current cannot safely dissipate, creating shock hazard on metalwork
• Remedy: Replace earth electrode, tighten connections, install supplementary bonding where required
• Typical remedial work: replace earth electrode, tighten connections, install supplementary bonding
• Prevention: Include earth electrode testing in every EICR and address deterioration early

4. Missing or Inadequate Supplementary Bonding

Supplementary bonding connects exposed metalwork (pipes, radiators, baths) in bathrooms and kitchens to the earthing system. Its absence means that if an electrical fault occurs, metalwork could become live.

• Cause: Original installation lacked bonding, or bonding was removed during renovation
• Risk: Metalwork in wet areas becoming live during an electrical fault
• Remedy: Install supplementary bonding between all exposed metalwork in bathrooms
• Typical remedial work: install supplementary bonding between all exposed metalwork in bathrooms
• Prevention: Always verify bonding during any bathroom or kitchen renovation

5. Absence of RCD Protection on cables in walls at <50mm depth

BS 7671 requires RCD protection (or mechanical protection) for cables embedded in walls at less than 50mm depth. This prevents nail/screw penetration from creating a shock hazard. Common in properties with surface-mounted or shallow-recessed cables.

• Cause: Cables chased into walls at shallow depth without mechanical protection
• Risk: DIY drilling or picture hanging could penetrate live cables
• Remedy: Add RCD protection to affected circuits or reroute cables with proper protection
• Typical remedial work: RCD addition or cable rerouting
• Prevention: Use certified electricians for all installation work who follow current depth requirements

6. Overloaded Circuits Without Adequate Protection

Circuits supplying more load than their protective device rating can handle creates overheating and fire risk. Often caused by adding appliances to original circuits not designed for modern power demands.

• Cause: Modern appliances (computers, gaming, kitchen gadgets) added to older circuits
• Risk: Cable overheating, insulation degradation, and potential fire
• Remedy: Redistribute load across circuits, upgrade cable and protective device, or add new circuits
• Typical remedial work: redistribute load across circuits, upgrade cable and protective device, or add new circuits
• Prevention: Have an electrician assess load during any major appliance addition or renovation