London EICR Safety Guide 2026: Common Electrical Faults Found in Homes, Rentals and Commercial Properties

Common Electrical Fault Types Identified During EICRs

EICR inspections can reveal conditions that are not obvious during normal use. A socket may still provide power, lighting may operate normally and a consumer unit may look acceptable from the outside while inspection and testing identifies a condition that needs attention.

The examples below are representative fault categories that can arise during EICR inspection and testing. They are not a ranked dataset, percentage breakdown or claim about how frequently RCD Electrical has encountered each issue.

If the main problem is a specific symptom such as repeated tripping, intermittent loss of power or an unidentified circuit fault, targeted electrical fault finding may be more appropriate than using a wider condition report as a diagnostic substitute.

What Does an EICR Actually Check?

An EICR examines the existing fixed electrical installation within the agreed inspection scope. In a typical property this can include wiring, socket-outlets, fixed lighting, the consumer unit or distribution boards, protective devices, earthing, bonding and permanently connected electrical equipment that forms part of the installation.

For rented homes in England, current GOV.UK guidance describes the inspection as covering the fixed electrical parts of the premises and explains that it is intended to identify issues such as overloaded installations, potential electric-shock or fire risks, defective electrical work and inadequate earthing or bonding.

Inspection and testing may include continuity, insulation resistance, polarity, earth fault loop impedance and protective-device testing where appropriate. The precise extent depends on the installation, access, safe isolation and any limitations agreed and recorded on the EICR.

The inspection process itself is covered more fully in What Does EICR Check Include UK?. This guide concentrates on interpreting findings and deciding what should happen next.

C1, C2, C3 and FI: What the EICR Codes Mean in 2026

C1, C2, C3 and FI are used to communicate the significance of observations recorded during periodic inspection and testing. A significant 2026 change is that the treatment of FI has changed under BS 7671:2018+A4:2026.

Electrical Safety First continues to provide industry guidance on selecting C1, C2, C3 and FI classifications. However, the IET has confirmed a specific change under BS 7671:2018+A4:2026: C3 and FI have been separated from C1 and C2 so that neither C3 nor FI alone results in an unsatisfactory outcome. Amendment 4 also changes the FI wording from “further investigation required without delay” to “further investigation is advised”.

Detailed classification examples belong in the specialist guide to C1, C2, C3 and FI EICR codes, rather than being duplicated here.

What EICR Findings Mean for Different Property Types

The electrical observation may be similar, but the practical and regulatory context can be different for an owner-occupied home, a rented property or a workplace.

Landlord EICR Requirements in England in 2026

Current GOV.UK guidance for England covers both private and social rented sectors. Landlords within the scope of the regulations must ensure that electrical installations in their rented properties are inspected and tested by a qualified person at least every five years and must obtain a report giving the results and the date of the next inspection.

Social rented sector: the 2026 transition

The regulations were extended to the social rented sector in 2025. They apply to social housing tenancies granted after 1 December 2025. For social housing tenancies granted before that date, the regulations came into force on 1 May 2026.

Transitional provisions require social landlords, for those earlier tenancies, to ensure that the electrical installation is inspected and tested by a qualified person before 1 November 2026. Subsequent inspections and tests must then be undertaken at least every five years.

The wider compliance position for rented homes is covered in London Rental Electrical Safety in 2026: What Landlords Need to Know About EICR Compliance.

How Is the EICR Context Different for Commercial Properties?

Commercial premises should not be treated as though they automatically fall under the same five-year landlord EICR rule that applies to rented homes within scope in England.

HSE guidance states that electrical equipment and installations must be maintained to prevent danger so far as reasonably practicable and advises arranging inspection and testing of fixed wiring installations to minimise deterioration leading to danger. For businesses, the inspection and maintenance approach should therefore reflect the installation, its condition, use and risk rather than relying on a blanket residential rule.

Shops, salons and high-street premises can also involve practical issues such as several distribution boards, altered circuits, fixed equipment and electrical supplies that cannot be isolated without planning around trading hours.

Those business-specific decisions are covered separately in Commercial EICR for Retail Shops, Salons and High Street Businesses in London.

What Should Happen After an EICR Identifies a Problem?

The next step should be based on the observation actually recorded. An EICR finding does not automatically mean that the consumer unit needs replacing or that the entire property needs rewiring.

1. Identify the affected part of the installation. Check which circuit, accessory, protective device, wiring section or distribution equipment the observation relates to.
2. Check the classification and report outcome. C1 and C2 need a different response from C3. If FI is recorded, check which version of the reporting standard was used and what the report says should happen next.
3. Separate known defects from unresolved causes. Some observations identify the required work directly. Others need further investigation before the repair scope can be established.
4. Arrange proportionate work. The response may be a local repair, targeted diagnosis, work at the consumer unit or wider wiring replacement depending on the actual condition found.
5. Keep the electrical records. Retain the EICR together with relevant confirmation or electrical certification for subsequent investigative or remedial work.

Where the report identifies deterioration affecting wider sections of fixed wiring, a rewiring assessment may be appropriate. A localised or unexplained defect should not be treated as evidence that a complete rewire is automatically necessary.

BS 7671 Amendment 4: What Changed for EICRs in 2026?

BS 7671:2018+A4:2026 has been published, but the previous Amendment 3:2024 position remains valid until 15 October 2026. The IET confirms that electrical installers may work to either edition during this transition period.

For EICRs, one of the most relevant changes concerns FI. The IET explains that Amendment 4 separates FI and C3 from the classifications that cause an unsatisfactory outcome. FI wording has also changed from “further investigation required without delay” to “further investigation is advised”.

This technical change should not be confused with a change to landlord legislation. Current GOV.UK guidance for rented homes in England continues to require landlords to complete remedial or further investigative work identified as necessary in the report within 28 days, or sooner if a shorter period is specified.