Does a Plastic
Consumer Unit
Fail an EICR?

A walk-through of plastic consumer unit EICR outcomes

The plastic consumer unit EICR question has a nuanced answer based on UK electrical regulations history. BS 7671 (the UK wiring regulations) was updated in January 2016 to require non-combustible consumer units in domestic dwellings. Plastic units installed before then were compliant at the time of install. EICR coding reflects this history rather than treating all plastic units as failures.

Why the 2016 regulation change happened

The change to require metal consumer units came after a series of London Fire Brigade investigations. The problem identified: faulty connections inside plastic consumer units sometimes caused localised heating that could ignite the plastic enclosure itself. The plastic became part of the fire load. BS 7671 17th Edition Amendment 3 (January 2016): introduced Regulation 421.1.201 requiring consumer units in domestic premises to have an enclosure made of non-combustible material. Metal became the standard. Pre-2016 installations: plastic was permitted plus widely used. Properties from the 1990s through 2015 typically have plastic units. Post-2016 installations: must use metal consumer units in domestic dwellings. Plastic remains permitted in some non-domestic applications. The retrospective question: what to do about millions of pre-2016 plastic installations that were compliant when fitted plus continue working safely?

How EICRs handle pre-2016 plastic units

The Electrical Safety Roundtable plus IET (Institution of Engineering and Technology) provided guidance on EICR coding for plastic consumer units. Standard guidance: a plastic consumer unit installed compliant with the regulations at the time of original installation typically receives a C3 (improvement recommended) code. What "improvement recommended" means: the installation is not dangerous but does not meet current standards. Recommend upgrade for compliance with 18th Edition. EICR overall outcome: a satisfactory EICR can include multiple C3 codes. The EICR fails only on C1 or C2 codes. Practical impact: a typical pre-2016 plastic consumer unit produces a satisfactory EICR with C3 recommendation to upgrade. Property remains lettable, mortgageable plus compliant for landlord regulations.

When plastic units receive C2 codes

Several specific situations elevate plastic consumer unit coding from C3 to C2 (failure). Located in escape route: plastic CU directly under wooden stairs that form the only fire escape route may receive C2. The fire risk is elevated because the escape route could be compromised. Signs of thermal damage: discolouration, melting, deformation or fire residue on the consumer unit. C2 minimum or C1 if active fault. Signs of arcing: burn marks around terminals, discolouration of insulation, smell of overheating. C2 typical. Damaged enclosure: cracks exposing internal components, missing knock-outs, gaps allowing finger access to live parts. C2 typical. Missing RCD protection: pre-2016 units may not have RCD protection on all circuits. RCD missing from socket circuits typically C2 under current regs. RCD missing from lighting may be C3. Post-2016 plastic install: plastic CU installed in a domestic dwelling after January 2016 was non-compliant when fitted. Coding typically C2.

Special cases plus exceptions

Several specific scenarios require careful EICR judgment. Plastic CU inside metal cupboard: some properties have plastic CUs enclosed in dedicated metal cabinet with fire-rated material. May still receive C3 with improvement note. HMO (House in Multiple Occupation) properties: stricter requirements under HMO regulations. AFDD (Arc Fault Detection Device) protection mandatory in some HMO categories. Plastic CU plus missing AFDD often C2. Commercial premises: BS 7671 does not require metal in non-domestic. Plastic typically C3 with improvement recommended for fire safety. Recently extended dwellings: extension or rewire after 2016 should use metal CU. If plastic was retained during extension that's likely a C2 because the install date is post-2016. Listed buildings: same EICR rules apply but installer judgment around aesthetic concerns. Consult conservation officer if metal installation requires changes to listed features.

Should I upgrade my plastic consumer unit?

Recommendation depends on context plus property situation. Owner-occupied home with pre-2016 plastic CU: typically not urgent. Upgrade as part of planned electrical work or when selling. C3 EICR outcome means no immediate compliance issue. Landlord-rented property: 5-yearly EICR is mandatory. Plastic CU typically C3. Consider upgrading at next rewire or major works to maintain best tenant safety profile. Property being sold: solicitor or buyer survey may flag plastic CU as a concern. Upgrade before sale typically improves saleability plus reduces buyer negotiation. Cost typical £500 to £900. Property in fire-sensitive location: under wooden stairs, near combustible storage or in escape route. Upgrade is genuinely safety-driven, not just compliance. Insurance claims context: plastic CU does not automatically void home insurance but may complicate fire-damage claims. Verify with insurer if unsure.

• EICR codes. C1 (immediate danger), C2 (potentially dangerous), C3 (improvement recommended), FI (further investigation).
• Plastic CU pre-2016. Typically C3. EICR satisfactory with recommendation to upgrade.
• Plastic CU post-2016 in dwelling. Typically C2. Was non-compliant when installed.
• Plastic CU damaged or in escape route. May escalate to C2. Inspector judgment.
• Upgrade cost. Typically £500 to £900 depending on board type plus circuits.

For a fixed-quote consumer unit upgrade or EICR plus subsequent upgrade if needed, our Consumer Unit Upgrades Milton Keynes service handles assessment, metal CU specification plus full install with electrical certification.

This article is one chapter of a wider local resource. To see how plastic CU coding connects with consumer unit upgrades, latest regulations plus the bigger picture, head to our full Consumer Units hub. The hub indexes every related article we have written for local property owners.

For a fixed-quote EICR plus consumer unit upgrade if needed, our Consumer Unit Upgrades Milton Keynes service handles assessment, metal CU specification plus install with full electrical certification. NICEIC accredited workmanship across Milton Keynes plus surrounding postcodes.