How many electrical fires occur in the UK each year?

Electrical Safety First reports that electricity causes over half of all accidental house fires in the UK, and that electrical products, rather than the fixed wiring, are behind most of them; damaged wiring and misused equipment such as overloaded extension leads account for many of the rest. The fatality risk from electrical fires is higher than from most other causes because electrical fires often start in concealed locations (wall voids, roof spaces, under floors) and can burn for a significant time before being detected.

What is an AFDD and does BS 7671 require them?

An Arc Fault Detection Device (AFDD) is a protective device that detects the electrical signatures of arc faults — abnormal electrical discharges that can occur in damaged, corroded, or deteriorating wiring and connections. Unlike RCDs (which detect earth leakage currents) and MCBs (which detect overcurrent), AFDDs detect the specific waveform characteristics of arcing faults that do not cause sufficient current to trip a standard protective device. Under BS 7671:2018+A4:2026, Regulation 421.1.7 requires them on single-phase socket-outlet circuits up to 32 A in high rise residential buildings, houses in multiple occupation, purpose-built student accommodation and care homes (since A2:2022), and recommends them elsewhere. So in an ordinary owner-occupied home they are recommended rather than mandatory, but in an HMO, care home, student block or high rise residential building they are required. Many electricians now fit them in ordinary homes too as part of comprehensive fire protection.

Why are metal consumer units required in dwellings?

Amendment 3 to BS 7671:2008, published in 2015 and in force from January 2016, introduced Regulation 421.1.201: a consumer unit in domestic premises must have a non-combustible enclosure, or sit in a non-combustible cabinet. Steel is the usual material. The requirement came from analysis of fires caused by arcing faults inside plastic consumer unit enclosures. When an arcing fault occurs inside a plastic enclosure, the arc can ignite the plastic and the fire can spread before any protective device operates. A metal enclosure contains the arc and any initial fire, giving the protective devices time to operate and preventing the fire from spreading to the surrounding structure. Plastic consumer units installed before 2015 do not need to be replaced immediately (unless there are other grounds for replacement), but any new consumer unit installed in a dwelling must have a metal enclosure.

What type of smoke alarm is best for bedrooms and living rooms?

Optical (photoelectric) smoke alarms are generally preferred for bedrooms and living rooms. Optical alarms detect smoke particles by measuring the scattering of light by smoke — they are more sensitive to slow-burning, smouldering fires, which are common in electrical fires that start in concealed locations. Ionisation smoke alarms are more sensitive to fast-flaming fires but are also more prone to nuisance alarms from cooking and toast. For comprehensive protection, a combination of optical and ionisation alarms (or combination alarms that incorporate both) provides the best coverage. Heat alarms (which detect a rapid rise in temperature) are recommended by BS 5839-6 for kitchens and other cooking areas where smoke alarms would cause frequent nuisance alarms.

How do I know if my home wiring is a fire risk?

Warning signs of dangerous wiring include: scorch marks or heat discolouration around socket outlets or switches; socket outlet face plates that are hot or warm to the touch; flickering or dimming lights, particularly on one circuit; circuit breakers that trip frequently without an obvious cause; a burning plastic smell from outlets, the consumer unit, or from the ceiling near light fittings; and wiring that is old (rubber-insulated wiring from before the 1960s is a significant fire risk as the insulation becomes brittle and cracks). If any of these signs are present, an EICR should be commissioned immediately to assess the installation condition.

Can overloaded extension leads cause fires?

Yes. Overloaded extension leads are one of the leading causes of electrical fires in UK dwellings. The total load connected to an extension lead must not exceed its rated current (typically 13A for a standard 4-way extension lead). High-power appliances such as kettles (3kW, 13A), toasters (2kW, 8.7A), and portable heaters (2kW to 3kW) must not be connected to extension leads with other high-power appliances. The rule is simple: one high-power appliance per socket outlet. Extension leads are for convenience — they are not intended to be used as a permanent substitute for additional socket outlets. If socket outlets are insufficient, additional sockets should be installed permanently by a qualified electrician.

How often should an EICR be carried out to prevent electrical fires?

The recommended period for EICRs in owner-occupied dwellings is every 10 years, or on change of ownership. For rented dwellings in England (private, and since 2025 social lettings), an EICR is now a legal requirement every 5 years under the Electrical Safety Standards in the Private Rented Sector and Social Rented Sector (England) Regulations 2020. However, for older installations (particularly those with rubber-insulated wiring, rewireable fuses, or no RCD protection), a shorter period — 3 to 5 years — is more appropriate. An EICR that identifies C1 (danger present) or C2 (potentially dangerous) deficiencies must be remediated promptly. Regular EICRs are the most effective way to identify deteriorating wiring before it causes a fire.

FIRE SAFETY GUIDE

Electrical Fire Prevention: AFDDs, Consumer Units, and Warning Signs

Electricity causes over half of all accidental house fires in the UK, according to Electrical Safety First. This guide covers arc fault detection devices (AFDDs), metal consumer units, smoke detector selection, and the warning signs of dangerous wiring that electricians and homeowners must recognise.

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Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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Key takeaways

01Electrical Safety First reports that electricity causes over half of all accidental house fires in the UK, and that electrical products, rather than the fixed wiring, are behind most of them. Overloaded extension leads and damaged wiring account for many of the rest.
02Arc Fault Detection Devices (AFDDs) can detect the electrical signatures of arcing faults before they develop into fires. BS 7671 recommends (but does not mandate) AFDDs for most domestic installations.
03Metal consumer unit enclosures have been mandatory for new installations in dwellings since Amendment 4 to BS 7671 (2015). Plastic consumer units are a fire risk if a fault causes arcing inside the enclosure.
04Optical smoke alarms are more effective than ionisation alarms for slow-burning fires (which are common in electrical fires starting in wall voids). BS 5839-6 recommends heat alarms rather than smoke alarms in kitchens, where cooking fumes would cause nuisance alarms from smoke detectors.
05Warning signs of dangerous wiring include scorch marks around sockets or switches, hot socket outlet plates, flickering lights, frequent circuit breaker trips, and the smell of burning plastic.

01 · Fire Safety Guide

Electrical Fire Statistics in the UK

Electrical fires are one of the leading causes of accidental house fires in the United Kingdom. Electrical Safety First reports that electricity causes over half of all accidental house fires. These fires cause deaths and serious injuries every year.

Over half

Of accidental house fires are caused by electricity

3,500+

Home fires a year from faulty appliances

Figures: Electrical Safety First.

The risk is not evenly distributed across all properties. Older properties with deteriorating wiring, properties with overloaded circuits and extension leads, and properties with plastic consumer units and no RCD protection are at significantly higher risk. Properties with modern installations, metal consumer units, RCD protection, and appropriate smoke and heat detection are much safer.

For electricians, understanding the causes of electrical fires and the protective measures available is essential — both for advising customers and for ensuring that installed work does not contribute to the problem.

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02 · Fire Safety Guide

Common Causes of Electrical Fires

The majority of electrical fires fall into three categories: faulty wiring, faulty or misused appliances, and poor installation workmanship. Understanding these causes helps electricians identify and remediate risks during EICR inspections and new installation work.

Deteriorating wiring and connections
Old rubber-insulated wiring (pre-1960s) becomes brittle and cracks, exposing conductors that can arc against each other or against earthed metalwork. Loose connections at socket outlets, switches, light fittings, and the consumer unit cause resistance heating and arcing. These faults are a leading cause of electrical fires in older properties.
Overloaded circuits and extension leads
Connecting more load than a circuit is rated to carry causes the cable to overheat. Standard twin-and-earth cable buried in thermal insulation has a significantly reduced current-carrying capacity. Overloaded extension leads in poor condition are a common ignition source.
Arcing faults
Arc faults occur when electricity jumps between damaged conductors, corroded connections, or degraded insulation. Arcing generates extremely high temperatures (over 6,000°C) that can ignite surrounding materials — including plastic cable insulation and timber joists — even when the arc current is too low to trip a standard MCB. AFDDs are specifically designed to detect and interrupt these faults.
Poor workmanship
Incorrectly rated fuses, undersized cables, joints made in ceiling voids or wall cavities without a junction box, and cables damaged during installation (penetrated by nails or screws) are all workmanship issues that can cause fires years after the installation was completed.

03 · Fire Safety Guide

Arc Fault Detection Devices (AFDDs) — BS 7671 Guidance

Arc Fault Detection Devices (AFDDs) detect the electrical signatures of arcing faults — abnormal electrical discharges that can develop in damaged or deteriorating wiring and connections. AFDDs continuously monitor the current waveform in a circuit and use algorithms to distinguish between the normal current waveform of household loads and the irregular waveform characteristic of an arc fault.

BS 7671 (18th Edition) addresses the use of AFDDs. It recommends that AFDDs should be provided in specific circumstances:

Bedroom circuits in single-family dwellings (recommended)
Locations where a fire would have particularly serious consequences
Locations where evacuation in the event of fire is difficult
Circuits supplying combustible materials (e.g. cable runs through timber-framed structures)

Required in some premises, recommended elsewhere: Under BS 7671:2018+A4:2026, Regulation 421.1.7 requires AFDDs on single-phase socket-outlet circuits up to 32 A in high rise residential buildings, HMOs, purpose-built student accommodation and care homes (a requirement since A2:2022). In all other premises, including an ordinary owner-occupied home, they are recommended on those circuits. Electricians should discuss AFDD options with customers during consumer unit replacements and new installations.

AFDDs are combined with MCBs in a single unit (AFDD+MCB) and replace standard MCBs on the ways they protect. They are currently more expensive than standard MCBs (typically £30 to £60 per way) but prices have reduced significantly and continue to fall. For bedroom circuits — where occupants are asleep and less likely to detect the early signs of a fire — the additional cost is a reasonable investment in safety.

04 · Fire Safety Guide

Smoke and Heat Detectors for Electrical Fire Protection

Smoke and heat detectors provide the earliest warning of an electrical fire, giving occupants time to escape and contact the fire brigade before the fire spreads. The type of detector and its location are important — the wrong type in the wrong location provides false security and nuisance alarms.

Optical (Photoelectric) Smoke Alarm

Detects smoke particles by measuring light scattering. More sensitive to slow-burning, smouldering fires — the type of fire commonly associated with electrical faults in wall voids and roof spaces. Less prone to nuisance alarms from cooking than ionisation alarms.

Best locations:

Living rooms, hallways, bedrooms, landings

Ionisation Smoke Alarm

More sensitive to fast-flaming fires. Can give nuisance alarms from cooking and toast. Less effective at detecting slow-burning electrical fires in their early stages.

Best locations:

Older recommendations — optical preferred in most domestic locations now

Heat alarm for kitchens — a heat alarm (detects rapid temperature rise) rather than a smoke alarm is required in kitchens where cooking fumes and steam would trigger nuisance alarms from a smoke detector. Heat alarms are slower to activate than smoke alarms but are appropriate for high-humidity, high-fume environments.
Interlinked alarms — BS 5839-6 recommends interlinked alarms (wired or wireless) so that when one alarm activates, all alarms in the property sound. This ensures occupants in remote rooms are alerted. Interlinked systems are required in new dwellings under Building Regulations Approved Document B.
Carbon monoxide alarms — not directly related to electrical fires, but BS 7671 encourages electricians to recommend CO alarms in properties with gas or oil appliances. Many modern combination smoke/CO alarm units are available.

05 · Fire Safety Guide

Consumer Unit Fire Protection — Metal Enclosures

Consumer units are the most common location for electrical arc faults in domestic installations — connections loosen over time, ageing protective devices develop faults, and the concentration of circuits in one location increases the risk.

Amendment 3 to BS 7671:2008 (2015) introduced Regulation 421.1.201: consumer units in domestic premises must have a non-combustible enclosure, which in practice means steel. This requirement exists because plastic consumer units, when subjected to an internal arc fault, can ignite — and the plastic enclosure then becomes fuel for the fire. A metal enclosure contains the arc and any combustion products within the enclosure, giving the protective devices time to operate and preventing fire spread.

New consumer units must be non-combustible — any consumer unit installed as a new installation or as a replacement in a domestic dwelling must have a metal (or other non-combustible) enclosure. This applies to both the main consumer unit and any sub-distribution board in a dwelling.
Existing plastic units — properties with plastic consumer units installed before 2015 are not required to replace them immediately. However, if the EICR reveals that the installation is due for a consumer unit replacement for other reasons (overloaded, no RCD protection, insufficient ways), the new unit must be metal.
Location matters — consumer units should not be installed in locations where they are exposed to moisture, thermal insulation, or combustible materials in direct contact with the enclosure. A metal consumer unit in a poorly ventilated location can still develop heat problems if the protective devices are overloaded.

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06 · Fire Safety Guide

Warning Signs of Dangerous Wiring

Homeowners and electricians should be aware of the warning signs that indicate dangerous or deteriorating electrical wiring. Early identification of these signs can prevent an electrical fire.

Scorch marks around socket outlets or switches — discolouration or scorch marks indicate that arcing has already occurred at that point. This is a serious warning sign requiring immediate investigation and remediation.
Hot or warm socket outlet face plates — a socket outlet that is warm to the touch indicates a loose connection or overloaded circuit. This is abnormal — socket outlets should not be warm under normal conditions.
Flickering or dimming lights — particularly if limited to one circuit or correlated with operating specific loads. This indicates a loose connection or overloaded circuit — both fire risks.
Burning plastic smell — the smell of burning plastic from sockets, the consumer unit, or ceiling voids is a serious warning sign. This can indicate that insulation is overheating or that a small fire has already started.
Frequent circuit breaker trips — a circuit that frequently trips without an obvious cause (such as a known high-load appliance) is overloaded or has a developing fault. Resetting a frequently tripping breaker without investigating the cause is dangerous.
Old wiring types — rubber-insulated wiring (black rubber outer sheath, pre-1960s), aluminium wiring (1960s to 1970s), and lead-sheathed wiring (pre-WWII) are all significantly past their design life and represent a serious fire risk. Any property with these wiring types should have an EICR and prioritise rewiring.

07 · Fire Safety Guide

EICR and Electrical Fire Prevention

An Electrical Installation Condition Report (EICR) is the most systematic way to identify electrical fire risks in an existing installation. The EICR assesses the condition of the fixed electrical installation — wiring, accessories, consumer unit, and earthing — and identifies deficiencies that could lead to fire or electric shock.

Deficiencies are classified as:

C1Danger present — risk of injury. Immediate remedial action required. The circuit or equipment presenting the danger should be disconnected until remediated.
C2Potentially dangerous — urgent remedial action required. Not immediately dangerous but could become so. Remediation should be completed as soon as possible.
C3Improvement recommended — not immediately dangerous but improvement would enhance safety. Typically for installations that do not meet current standards but are not inherently unsafe.

An EICR that reveals C1 or C2 deficiencies — such as deteriorating wiring, no earth bonding, or inadequate RCD protection — must be addressed promptly. An installation with known deficiencies and no remedial action taken represents a serious and preventable fire risk. Use the EICR certificate app to complete condition reports on site and provide customers with a clear, professional assessment of their installation's safety.

08 · Fire Safety Guide

For Electricians: Advising on Electrical Fire Prevention

Electricians are uniquely positioned to advise homeowners on electrical fire prevention. Every consumer unit replacement, EICR, and new installation is an opportunity to discuss AFDDs, smoke alarm placement, RCD protection, and the condition of existing wiring.

EICR Certificate App

Complete Electrical Installation Condition Reports on your phone. AI-assisted inspection guidance, code classification, and instant PDF for the homeowner. Every EICR is an opportunity to identify and address fire risks.

EIC for Consumer Unit Upgrades

Consumer unit replacements (to metal enclosures with RCD protection and AFDDs) require an EIC. Complete it on site with AI board scanning and send the PDF to the homeowner immediately.

Frequently Asked Questions About Electrical Fire Prevention

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Electrical Fire Prevention: AFDDs, Consumer Units, and Warning Signs

Key takeaways

Electrical Fire Statistics in the UK

Get the BS 7671 A4:2026 Cheat Sheet — free

Common Causes of Electrical Fires

Arc Fault Detection Devices (AFDDs) — BS 7671 Guidance

Smoke and Heat Detectors for Electrical Fire Protection

Optical (Photoelectric) Smoke Alarm

Ionisation Smoke Alarm

Consumer Unit Fire Protection — Metal Enclosures

Issue EICs for consumer unit upgrades on site

Generate RAMS in minutes

Warning Signs of Dangerous Wiring

EICR and Electrical Fire Prevention

For Electricians: Advising on Electrical Fire Prevention

EICR Certificate App

EIC for Consumer Unit Upgrades

Frequently Asked Questions About Electrical Fire Prevention

How many electrical fires occur in the UK each year?

What is an AFDD and does BS 7671 require them?

Why are metal consumer units required in dwellings?

What type of smoke alarm is best for bedrooms and living rooms?

How do I know if my home wiring is a fire risk?

Can overloaded extension leads cause fires?

How often should an EICR be carried out to prevent electrical fires?

Continue reading

AFDD Guide

EICR Certificate App

Electrical Safety Checks for a New Home

Consumer Unit Upgrade Guide

Electrical Handover Documentation

EIC Certificate App

What electricians say

One App for Everything!

Fantastic app for electricians

Absolutely amazing

Trusted by electricians across the UK

Complete EICRs and Consumer Unit Upgrade Certificates On Site