EICR Codes Explained: C1, C2, C3 and FI

No — and it is important to be clear about this. This tool provides guidance based on Best Practice Guide 4 (Issue 7.2). It helps you explore likely coding for common observations, but it does not know the specific details of the installation in front of you, the results of your tests, or the conditions present at the time of inspection. Final classification of every observation always remains the responsibility of the qualified and competent inspector. No tool, checklist or software can substitute for professional judgement, experience, and thorough inspection and testing.

No. This is one of the most persistent myths in the electrical inspection industry, and it is important to address it clearly. A plastic consumer unit is not a codeable defect by virtue of its material alone. Best Practice Guide 4 style guidance is explicit on this point. The defect — if any exists — must be identified and coded. If the consumer unit has missing blanks, is damaged, shows signs of overheating, has poor assembly, or is located in a position presenting a specific fire risk, those issues should each be assessed and coded on their merits. Where no other defect is identified, a plastic consumer unit is not codeable. Incorrectly coding a plastic consumer unit without a specific defect misleads clients and is not consistent with BPG4 Issue 7.2. See also: PRS 2025 EICR update guide.

Best Practice Guide 4 Issue 7.2 classifies a Type AC RCD installed where Type A is required as C3, and that is the default position used by this tool. Final classification remains the inspector's judgement. A Type AC RCD provides residual current protection but does not detect pulsating DC residual currents. BPG4 Issue 7.2 classifies this departure as C3.

No. Main protective bonding is only required to extraneous-conductive-parts — parts that introduce a potential from outside the installation into the building. Not all metallic services, sinks, baths or pipework qualify as extraneous-conductive-parts. For example, a metallic sink connected only to plastic pipework does not introduce an external potential and is therefore not an extraneous-conductive-part requiring main bonding. Automatically coding the absence of bonding to such parts is incorrect and can mislead clients. Before applying any bonding code, the inspector must confirm the nature of the service or part in question.

Because the risk presented by a defect often depends on the specific circumstances of the installation and the condition of the installation at the time of inspection. This is at the heart of Best Practice Guide 4 (Issue 7.2) — the defect is coded, and the code reflects the actual risk presented, not a blanket rule. For example, a damaged outdoor accessory presents an immediate danger (C1) if live parts are directly accessible through the damage, but a significant risk requiring urgent attention (C2) if the enclosure is damaged but live parts remain inaccessible. This is why the tool asks conditional questions for certain observations — the same fault can present very different levels of risk in different scenarios.

Best Practice Guide 4 (BPG4) is a guidance document produced by Electrical Safety First in collaboration with industry bodies including the ECA, NAPIT, NICEIC and others. It provides guidance to help inspectors apply consistent and appropriate coding to EICR observations. BPG4 encourages a defect-based, risk-assessed approach to coding rather than blanket rules based on age or materials. It uses the C1, C2, C3 and FI code system defined by BS 7671 and the model forms. This tool uses BPG4 Issue 7.2 as its default approach. See also: our EICR information hub and landlord EICR information.