Not automatically. A plastic consumer unit can pass an EICR if it’s safe, correctly installed, and shows no signs of overheating or damage.
However, it may be coded (C1/C2/FI/C3) if the enclosure is cracked, heat-damaged, poorly sited, or if there’s evidence of burning/loose connections that increase fire risk. Since the 18th Edition (BS 7671), metal consumer units are strongly preferred for improved fire containment.
Last updated: 2026
Reviewed by: London Safety Certificate compliance team
Key Takeaways
- A plastic consumer unit alone does not automatically fail an EICR based solely on material.
- EICR assesses compliance with safety standards, including risks posed by flammable materials.
- Findings of thermal damage, brittleness, or degradation in plastic units could result in failing codes like C1 or C2.
- Updated regulations recommend metal over plastic for fire safety, influencing EICR evaluations on older plastic units.
- Regular EICRS can lead to recommendations (C3) to upgrade plastic units to metal for enhanced safety compliance.
Table of Contents
Understanding the Role of Plastic Consumer Units in an EICR
Plastic consumer units were common in older UK homes. During an EICR, the electrician isn’t “failing plastic” – they’re assessing risk. The unit is checked for heat damage, cracks/brittleness, secure terminations, signs of arcing, and whether the enclosure helps contain fire if a fault occurs.
What EICR codes can a plastic consumer unit get?
A plastic consumer unit is not an automatic fail. The electrician EICR codes what they find.
- C1 (Danger present): immediate risk (e.g., signs of burning, exposed live parts, severe heat damage).
- C2 (Potentially dangerous): urgent remedial work needed (e.g., overheating evidence, enclosure compromised, serious defects increasing fire risk).
- FI (Further investigation): testing/inspection couldn’t confirm safety (e.g., suspected heat damage/loose connections that require investigation).
- C3 (Improvement recommended): not unsafe today, but upgrading to metal is advised for best practice.
Quick verdict: will it pass or fail?
| What the electrician sees | Likely EICR outcome |
|---|---|
| Plastic unit is intact, no heat marks, terminations sound | Often Pass (may still get C3 upgrade recommended) |
| Discolouration, slight melting, burning smell, loose tails | C2 (urgent remedial) |
| Exposed live parts, severe burning/charred busbar/terminals | C1 (danger present – immediate action) |
| Can’t confirm safety without opening/isolating/testing further | FI (further investigation) |
Common EICR outcomes for plastic consumer units (what usually triggers each code)
- C3 (upgrade recommended): plastic unit is intact, no heat damage, terminations are sound – but metal is preferred for fire containment (especially in higher-risk setups).
- C2 (urgent): heat marks, melting, brittle/cracked enclosure near live parts, loose/overheating signs, or inadequate containment risk.
- C1 (immediate danger): burning/charred parts, exposed live conductors, severe overheating/arcing evidence.
- FI (further investigation): suspected overheating/loose connections where inspection/testing can’t confirm safety without deeper checks.
This alone will improve quality massively.
When does a plastic consumer unit become a fire risk?
A plastic enclosure becomes a concern when heat or arcing is already happening. Common triggers:
- loose or overheated terminals inside the unit
- discoloration/brown marks, melted plastic, burning smell
- cracked/brittle enclosure (age/heat damage)
- poor installation location (limited ventilation, combustible surroundings)
If these are present, the unit may be coded C2 or C1 depending on severity.
Top 7 reasons plastic boards get coded
The 7 most common reasons a plastic consumer unit gets coded on an EICR
- Heat damage around MCBs/RCBOs (brown marks / distortion)
- Loose tails / loose main switch terminations (classic overheating cause)
- Cracked or brittle enclosure near live parts (age/impact/heat)
- Poor siting (combustible surface, cramped cupboard, poor ventilation)
- Signs of arcing (black soot marks, buzzing, intermittent power issues)
- Missing/incorrect blanks (gaps that expose accessible live parts)
- General poor workmanship (untidy conductors, damaged insulation, non-credible alterations)
Metal vs plastic consumer units (what BS 7671 expects)
BS 7671 (18th Edition) strongly favours non-combustible consumer unit enclosures (typically metal) in many domestic settings because they help contain fire and hot debris if a fault occurs.
This doesn’t mean every plastic unit automatically fails – EICR outcomes depend on risk, condition, and installation quality – but upgrading is commonly recommended where fire risk is higher or the existing unit is deteriorating.
Should landlords replace plastic consumer units?
Landlords must ensure electrics are safe and maintained. A plastic consumer unit may be acceptable if it’s safe and tested, but upgrading to metal is often recommended if:
- the unit is heat damaged, cracked, or poorly installed
- EICR returns C2/C1/FI linked to the board or its condition
- you want stronger compliance evidence for agents/insurers
- the property is higher risk (HMOs, older wiring, repeated faults)
See Our full guide on landlord electrical safety certificate rules.
How to reduce the chance of a fail ?
How to reduce the chance of a failed visit (without DIY)
- Make the consumer unit accessible (not boxed in, not blocked by storage).
- Ensure the electrician can access the meter area and main switch.
- If the property is tenanted, arrange access to all rooms and notify about short interruptions.
- Have any previous EICR handy (helps spot repeat issues and saves time).
- If you’ve had tripping/burning smells, mention it before the visit so testing is planned properly.
How much does it cost to replace a plastic consumer unit in London?
Most consumer unit upgrades in London vary based on circuits and protection required. Consumer Unit Cost usually depends on:
- number of circuits / complexity
- whether RCBOs, SPD, or other protection is needed
- condition of existing wiring and tails
- access and isolation requirements (tenanted homes often take longer)
Rule of thumb: a simple upgrade is usually cheaper than one that also needs remedial fixes discovered during the changeover.
If you want an accurate quote, send bedrooms + photos of the consumer unit + how many boards.
Frequently Asked Questions
Will a plastic consumer unit automatically fail an EICR?
No. It’s coded based on safety, condition, installation, and fire risk – material alone doesn’t automatically fail.
What EICR code is given for a plastic consumer unit?
Often C3 (recommend upgrade) if otherwise safe, but C2/C1/FI if defects or evidence of overheating is found.
Do landlords have to replace plastic consumer units?
Not automatically – landlords must keep electrics safe. Replacement is usually recommended when risk or defects exist, or to strengthen compliance.
How long does an EICR take?
Most homes take a few hours depending on size, circuits, and access.
Can you replace the consumer unit and do EICR at the same time?
Often yes – if access and safe isolation is possible. Any faults found may require additional remedial work.
Conclusion
A plastic consumer unit does not automatically fail an EICR, but it can be coded if it shows heat damage, cracking, poor installation, or any defect that increases fire risk. BS 7671 (18th Edition) generally favours metal enclosures for better fire containment, so upgrading is often recommended – especially for landlords who need clean compliance evidence for agents, insurers, or councils. If you want a fast answer, book an EICR or send a clear photo of your consumer unit and we’ll advise whether it’s likely to pass or needs upgrading.