The EICR Coding Decision Framework: Demystifying C1, C2, C3 & FI

Electrical Installation Condition Reports (EICRs) are among the most contentious documents in the UK electrical trade. Inconsistent classification of defects creates client disputes, unnecessary remedial bills, and commercial liability. Here is a structured engineering framework for applying C1, C2, C3, and FI codes objectively.

The Purpose of an EICR

An EICR is an engineering assessment of an existing installation against the safety intent of current standards (BS 7671). It is fundamentally not a snagging listto bring an older installation up to the latest edition. The core question for every observation is: Does this condition present a realistic risk of electric shock, fire, or burns under normal or fault conditions?

Code C1: Danger Present

Definition: Risk of injury is immediate. Persons using the installation are at immediate risk of electric shock or fire without another fault occurring.

• Immediate action required: The inspector has a professional duty to make the situation safe immediately (with client permission) or isolate the dangerous circuit and issue an immediate danger notification in writing.
• Typical C1 Examples:
  • Exposed live conductors accessible to touch (broken accessory covers, missing blanking plates on distribution boards).
  • Conductive parts that are live due to an un-cleared ground fault or reversed polarity on supply terminals.
  • Severe thermal damage with active charring and exposed bare live copper.

Code C2: Potentially Dangerous

Definition: Urgent remedial action required. The condition does not present immediate danger now, but could lead to danger in the event of a secondary fault or foreseeable event.

• Outcome: Any C1 or C2 observation results in an overall Unsatisfactory report.
• Typical C2 Examples:
  • Absence of reliable earthing or main protective bonding to incoming metallic services (water/gas).
  • Earth fault loop impedance (Zs) values exceeding maximum permitted disconnection thresholds where no supplementary RCD protection exists.
  • Lack of RCD protection on socket-outlets that can reasonably be expected to supply portable equipment outdoors.
  • Undersized protective conductors unable to withstand prospective fault currents under the adiabatic equation.

Code C3: Improvement Recommended

Definition: Non-compliance with the current edition of BS 7671 that does not present immediate or potential danger. It highlights areas where safety could be enhanced.

• Outcome: C3 observations alone do not make the report Unsatisfactory.
• Typical C3 Examples:
  • Absence of RCD protection on standard indoor lighting circuits installed to a previous edition, where cables are buried deeper than 50 mm or mechanically protected.
  • Absence of Surge Protection Devices (SPDs) or Arc Fault Detection Devices (AFDDs) in an existing older installation.
  • Missing warning notices, circuit directory charts, or periodic inspection labels.

Code FI: Further Investigation Required

Definition: The inspector cannot fully determine the safety of a circuit or component within the agreed extent and limitations of the inspection.

• Outcome: By definition, an FI observation results in an overall Unsatisfactory assessment until investigated.
• When to use FI: Only when evidence suggests an underlying hazard that cannot be verified without intrusive dismantling outside the agreed scope (e.g. borrowed neutrals between consumer units or unverified sub-main feeds).

Summary Decision Matrix