We are often asked by landlords and managing agents whether a plastic consumer unit, the box that holds the main switch and circuit breakers, is still allowed. Some have been told by an electrician that it must be replaced with a metal one, while others have an EICR marked satisfactory with the same unit in place. It is easy to see why the question causes confusion.
The short answer is that a plastic consumer unit is not automatically non-compliant, and there is no law requiring every existing plastic unit to be removed. Whether it is acceptable depends on the type of building, where the unit is located and its condition. Under the Regulatory Reform (Fire Safety) Order 2005, the real question is whether the fire risk it presents has been properly assessed and reduced. In this post we explain what the wiring standard says, how electricians code plastic units, and how a Responsible Person should approach them.
Why plastic consumer units became an issue
Around 2014, fire investigators, including the London Fire Brigade, reported a rise in fires that started at consumer units in homes. Most were caused by poor workmanship, such as connections that had not been tightened properly, which allowed heat to build up inside the unit. Once the plastic enclosure caught fire, flames could escape and spread to the surroundings.
In response, an amendment to BS 7671, the national standard for electrical installations, introduced a new requirement from 1 January 2016. Within domestic (household) premises, consumer units must now have an enclosure made of non-combustible material, such as steel, or be housed inside a non-combustible cabinet. The aim is to contain a fire inside the unit for long enough to stop it spreading.
What this means for existing plastic units
Three points are worth understanding. First, the requirement applies to new work. A plastic unit installed correctly before 2016 met the standard in force at the time, and BS 7671 does not require it to be replaced simply because the standard has changed. Second, the requirement applies to domestic premises only, so a plastic distribution board in an office, shop or warehouse can still meet the current standard. Third, BS 7671 is a British Standard and is not itself law, although it is the accepted way of showing that an installation is safe.
When an electrician carries out an EICR, they record a plastic unit according to its risk. Electrical Safety First's best practice guidance, which is widely used by inspectors, recommends a C3 code, meaning improvement recommended, where a plastic unit in a dwelling sits under a wooden staircase or within the sole route of escape. Elsewhere, it suggests no code is needed. A C3 does not make the report unsatisfactory. A plastic unit should only be coded as dangerous or potentially dangerous, C1 or C2, if there is an actual defect, such as signs of overheating, scorching or loose connections.
Ask your electrician to explain the codeIf you are told that a plastic consumer unit must be replaced, ask which code it has been given on the EICR and why. A unit coded C3 is a recommendation for improvement. A C1 or C2 should be supported by a description of the specific defect that makes it dangerous.
Where the Fire Safety Order comes in
The Fire Safety Order applies to workplaces and other non-domestic premises, and to the common parts of residential buildings, such as the shared hallways and stairs in blocks of flats and HMOs. It does not apply inside a single private home. This matters because many plastic consumer units, particularly in converted HMOs and older blocks, are located in exactly those common parts, often in a hallway cupboard or under the stairs.
The Order does not mention consumer units, and it does not use the idea of a unit being compliant or non-compliant. Instead, Article 9 requires the Responsible Person to make a suitable and sufficient assessment of the fire risk, and Article 8 requires them to take the general fire precautions needed to keep people safe. In practice, this means identifying sources of ignition, reducing the chance of a fire starting, and making sure that people can escape if one does.
A consumer unit is a recognised source of ignition. When it is located in the only escape route, a fire starting there could block the way out for everyone above it. That is why the location of a plastic unit is often more important to the fire risk than the material itself.
What a fire risk assessor will look at
When we find a plastic consumer unit during a fire risk assessment, we consider it in the context of the building as a whole, such as:
- whether it is in a protected escape route, and whether that route is the only way out
- whether it sits under a timber staircase, where a fire could quickly damage the stair
- whether the building has sleeping accommodation, such as an HMO, a hotel or a care home
- its condition, and whether a current EICR shows it to be in good order
- what is stored around it, as cupboards housing meters and consumer units often become storage for paint, cardboard and cleaning products
- whether the area is covered by fire detection, so a fire would be detected early
A sound plastic unit in a staff kitchen of a single-storey office is likely to present a low risk, and we would not normally recommend replacing it. The same unit in the communal hallway of a three-storey HMO, at the foot of the only staircase, is a different matter.
How to reduce the risk
Where a plastic unit presents a significant risk, there are several ways to deal with it. The right choice will depend on the building, the condition of the installation and your plans for the property:
- replace the unit with a metal consumer unit, which is often the simplest long-term solution and may be sensible if other electrical work is planned
- house the existing unit inside a suitable non-combustible cabinet installed by an electrician
- enclose the unit and meter in fire-resisting construction where they are located in an escape route, which many local authorities ask for in HMOs
- keep the area around the unit clear of storage, and keep any enclosure door shut
- make sure the installation is covered by a current, satisfactory EICR
Record your decisionWhatever approach you take, it should be recorded in your fire risk assessment. If you decide that a plastic unit can stay, the assessment should explain why the risk is acceptable. If you decide to replace or enclose it, keep the electrician's certificate with your fire safety records.
Need a fire risk assessment?
Our ABBE Level 3 and 4 qualified assessors look at electrical sources of ignition, including consumer units, as part of every fire risk assessment, and give clear, proportionate recommendations for each building. We work with landlords, managing agents and businesses across the North West, North Wales and the West Midlands. If you would like an assessment or a review of an existing one, please get in touch.
Get a quote Fire risk assessmentsThis article provides general guidance only and does not replace a fire risk assessment or professional advice specific to your premises. The Fire Safety Order applies in England and Wales. Other legislation and guidance referred to apply in England unless otherwise stated.