What does the consumer unit do?
The consumer unit—often called the fuse box—distributes electricity to the property’s final circuits and contains protective and isolation devices. Depending on its age and design, these may include rewireable fuses, MCBs, RCDs, RCBOs, surge protection and the main switch.
Replacing it can improve protection and circuit separation, but it does not renew the cables, sockets, lights or accessories on the existing circuits.
When is replacement normally considered?
- Damage, overheating, burning, loose parts or accessible live components.
- Protective devices that are defective, unsuitable or no longer safely supportable.
- No practical way to provide Scotland’s required 30 mA RCD protection using the existing arrangement.
- Insufficient capacity or ways for planned circuits.
- Poor circuit separation that creates avoidable disruption or safety concerns.
- An EICR identifies defects for which replacement is the proportionate remedy.
- Major alteration, extension, electrification, solar, battery or EV work requires redesigned distribution.
An EICR recommendation needs a reason
Ask which observation drives the recommendation, its classification, what risk exists, whether another compliant remedy is available and what the replacement quotation includes.
Does an old fuse box automatically fail an EICR?
No. Electrical installations are assessed for safety, not simply against the age of their equipment. Rewireable fuses or older breakers do not automatically prove danger, although the installation may lack protection expected by current standards and may have defects that need attention.
In a Scottish rental, there is also a specific baseline: one or more RCDs rated at no more than 30 mA must be present in the main or principal consumer unit, normally protecting socket circuits at minimum. No RCD means the house does not meet the Repairing Standard.
Does a plastic consumer unit need replacing?
Not solely because its enclosure is plastic. Industry Best Practice Guide 1 expressly says a consumer unit need not be replaced only because it is made from combustible material. Location, signs of thermal damage, enclosure condition and the wider risk must be considered.
Current BS 7671 practice generally calls for non-combustible enclosures for new domestic consumer units. That requirement for new work should not be turned into a blanket claim that every existing plastic unit is automatically unsafe.
Can RCD protection be added without replacement?
Sometimes. Electrical Safety First guidance notes that a complete replacement is not always necessary merely because an existing board lacks RCD protection. Depending on compatibility, condition and available space, protection might be provided using a separate enclosure or another designed alteration.
A full replacement may still be the cleaner or more economical option when several circuits need protection, existing equipment is obsolete, separation is poor or further work is planned. The contractor should compare the viable options.
RCD arrangements or individual RCBOs?
A shared RCD can protect a group of circuits. An RCBO combines residual-current and overcurrent protection for one circuit. Individual RCBOs usually improve separation: one fault is less likely to disconnect unrelated lighting, alarms, heating or refrigeration.
The design should also consider the correct RCD type for connected electronic equipment, any surge-protection assessment, main-switch rating, fault-current capacity and future circuits. Product selection belongs in the electrical design, not a generic specification copied between properties.
What testing happens before and after replacement?
Existing circuits should be assessed before final commitment because a new, more sensitive protective device may reveal insulation leakage, borrowed neutrals, incorrect connections or other defects. These issues are not caused by the new consumer unit; the testing exposes existing problems.
After installation, the electrician should inspect and test the work and connected circuits as required, label the devices and provide certification. Do not accept an unexplained board change with no schedules of inspections and results.
What certification should the landlord receive?
A consumer-unit replacement is normally covered by an Electrical Installation Certificate with schedules of inspections and test results. Keep it with:
- the preceding EICR and quotation;
- evidence resolving each relevant observation;
- the final circuit schedule and device information;
- instructions for RCD or RCBO test buttons;
- any surge-protection documentation; and
- building-warrant or completion evidence where applicable.
Confirm Scottish building-standards requirements before work starts. Whether a warrant is needed depends on the scope, property and circumstances; the electrical certificate is not a substitute for any required statutory approval.
How should work be planned around tenants?
- Give appropriate notice and agree access.
- Explain the expected shutdown and which facilities will be unavailable.
- Protect refrigerated goods, medical equipment, alarms, heating and remote-working needs.
- Arrange safe temporary measures if work cannot finish in one visit.
- Test all relevant circuits before re-energising them.
- Update labels and give occupants clear instructions.
- Record unforeseen circuit repairs separately and transparently.
What should a quotation make clear?
- The proposed enclosure, main switch and protective devices.
- Whether circuits receive shared RCDs or individual RCBOs.
- Whether surge protection is included and the assessment behind the decision.
- Pre-work testing and the treatment of discovered defects.
- Earthing, bonding and meter-tail work included or excluded.
- Labelling, certification, making good and waste removal.
- Access assumptions and expected duration.
Consumer-unit work does not normally include decorating, plaster repairs, flooring or unrelated circuit rewiring unless specifically itemised.
Frequently asked questions
Will a new consumer unit make an unsatisfactory EICR satisfactory?
Only if it resolves all observations responsible for the unsatisfactory result. Circuit, earthing, bonding or accessory defects may require separate remedial work and evidence.
Does the property need a full rewire at the same time?
Not automatically. Testing determines whether existing circuits are safe for continued service or need repair or replacement.
Can the landlord choose the cheapest board?
The selected equipment must be suitable for the installation, fault conditions, connected loads and expected use. Compare the design, included testing and certification—not only the enclosure price.
General information only. Consumer-unit work and EICR classification require competent assessment of the actual installation. Confirm building-standards requirements and the precise scope before authorising work.