EICR failed for high R1+R2 or poor CPC continuity

Circuit protective conductor (CPC) continuity confirms that exposed conductive parts are connected back to the origin for fault protection. High (R1+R2) values or an open CPC can mean automatic disconnection may not operate within required time under fault conditions — a potentially dangerous situation often coded C2, or C1 where immediate risk is present.

A single high reading does not automatically condemn an entire installation. The inspector should identify the circuit, compare results against applicable limits for the protective device and earthing arrangement, and consider test method limitations. FI may be used where connections are inaccessible or results are inconclusive.

This page explains the narrow R1+R2 / CPC continuity observation. Related earth-fault loop impedance issues at the origin are covered separately in the high Ze guide.

R1 is typically the line conductor resistance and R2 the circuit protective conductor resistance measured end-to-end on a circuit. Their sum contributes to earth fault loop impedance (Zs) at the furthest point of the circuit, which is compared against maximum values for the protective device to operate.

Continuity testing verifies that the CPC is present and connected from accessories and equipment back to the origin. An open or high-resistance CPC breaks the fault path and can leave metalwork energised under fault conditions until someone touches it.

Test results appear on the schedule of test results alongside circuit references. The observation narrative should tie the code to specific circuits and measured values rather than generic wording such as “high readings”.

Locate the failing circuit on the schedule — kitchen sockets, lighting, shower, or other labels as recorded. Compare the stated (R1+R2) or continuity result with the inspector's remarks and classification code.

Check whether the inspector noted test method constraints: parallel paths, RCBO combinations, inability to isolate neutrals, or inaccessible junction boxes. These can affect interpretation and may justify FI rather than a firm C2.

Read companion observations on the same circuit. Loose connections at the consumer unit, damaged cables, or incorrect polarity may explain the reading and expand remedial scope beyond a single high number.

• C1: immediate danger suggested — for example confirmed loss of protective earthing on accessible Class I equipment with live parts present under fault.
• C2: potentially dangerous — high (R1+R2) or failed continuity where fault protection appears compromised for the circuit in context.
• C3: improvement recommended — marginal readings or legacy arrangements that do not meet the threshold for potential danger as judged on site.
• FI: further investigation — concealed joints, incomplete isolation for testing, or inconclusive results requiring additional inspection.

Loose or corroded terminations at sockets, junction boxes or the consumer unit increase resistance. DIY alterations and poorly made junctions in floor voids are frequent findings in converted flats.

Damaged CPCs from historic cable types, rodent damage, or screw penetrations can raise readings or open the conductor entirely. Extensions added without proper CPC continuity through metal conduit systems may also fail.

Test artefacts occur: parallel earth paths through metal conduit or trunking, shared neutrals, or electronic equipment on the circuit can distort readings. Competent retesting after isolation helps confirm true values.

Remedial work starts with safe isolation and confirmation of the failing circuit. The electrician may test at multiple points to locate high-resistance joints, repair terminations, replace damaged cable sections, or reconfigure incorrect connections.

Where junction boxes are inaccessible without fabric disturbance, FI may remain until agreed opening of floors, ceilings or boxing. Quotations should separate confirmed repairs from investigative allowances.

After correction, continuity and (R1+R2) or Zs measurements should be repeated and recorded. Appropriate certification should be issued for the work undertaken.

Where the report requires further investigative or remedial work, regulation 3(4) can require a qualified person to do that work within 28 days, or any shorter period the report states, starting with the inspection and test. Regulation 3(2A) and 3(6A) also record a reasonable-steps position, including where a tenant prevents entry. A continuity reading does not, by itself, decide that duty.

Prioritise circuits serving bathrooms, kitchens and outdoor equipment where fault risk and contact likelihood intersect. Document access arrangements if tenant occupation limits investigation.

London EICR Certificates coordinates inspection and remedial referrals; engineering judgement on the signed report determines scope, not informal reassurances that “readings are often high in old flats”.

“High R1+R2 always means full rewire” overstates many cases where localised faults at joints cause the reading.

“If sockets work, CPC must be fine” is false. The protective function is about fault conditions, not everyday operation.

“Retesting without isolation gives the same result” ignores parallel paths that can mask open CPCs until properly isolated.

Provide the EICR schedule pages showing failing circuits and values, plus observation numbers. Note any areas with suspected DIY work or recent alterations.

Ask whether the quotation includes isolation, fault location, repair, retesting and certification. If FI was recorded, agree how investigative work is charged if the fault is not immediately visible.

Check residential pricing through the homepage calculator when booking follow-up appointments. Retain test results with the original EICR for compliance records.

Do not ignore C1 or C2 CPC observations. Avoid using circuits identified as potentially unsafe until assessed. If equipment feels hot, trips repeatedly, or shocks are suspected, seek urgent professional help.

Ask the remedial electrician to explain which circuits are affected and whether any should remain isolated pending repair. Use observation numbers in all correspondence.

Editorially checked on 3 October 2026. The regulation 3 points were read that day from the revised legislation.gov.uk text. Continuity readings and classification examples are not a competent electrical sign-off. Technical review remains pending.

Maximum permitted values depend on protective device type, earthing arrangement and measured method. The competent person's on-site assessment determines coding and remedial scope.

This article was editorially reviewed on 2026-10-03. It provides general operational guidance for London property decision-makers and is not personalised legal advice.

Electrical classification on an EICR depends on the installation, the observations recorded and competent professional judgement. Always read your own report and seek competent advice for your property.