Electrical safety in UK homes has evolved significantly over the years. From basic fuses to modern consumer units with MCBs and RCDs, each step has reduced the risk of electric shock and fire. However, electrical fires still occur, often due to faults that traditional protection devices cannot detect. This is where Arc Fault Detection Devices (AFDDs) come in.

AFDDs are one of the most important yet least understood developments in UK domestic electrical protection.

What Is an Arc Fault?

An arc fault occurs when electrical current jumps across a damaged or loose connection instead of flowing smoothly through a conductor. This creates intense heat, sometimes exceeding several thousand degrees Celsius, without drawing enough current to trip a standard circuit breaker.

Common causes of arc faults in UK homes include:

• Damaged appliance flexes
• Loose plug pins
• Crushed cables behind furniture
• Ageing wiring insulation
• Poor DIY electrical work

These faults can smoulder for long periods before igniting surrounding materials such as timber, carpets, or insulation.

Why Traditional Protection Is Not Enough

MCBs are designed to protect against overloads and short circuits. RCDs protect against electric shock caused by current leakage to earth. Neither device is designed to detect the electrical signature of an arc fault.

This means an appliance with a damaged cable could continue operating while producing dangerous heat, without triggering any protection device. AFDDs are designed specifically to close this gap.

How AFDDs Work

AFDDs continuously monitor the waveform of electrical current. Arc faults create distinct, irregular patterns in current flow that differ from normal appliance operation.

Using advanced electronic monitoring, AFDDs can:

• Detect series and parallel arc faults
• Distinguish dangerous arcing from normal switching sparks
• Disconnect the circuit before a fire starts

This level of monitoring is particularly important in modern homes filled with electronic appliances.

AFDDs and UK Wiring Regulations

The UK Wiring Regulations (BS 7671) increasingly recommend AFDDs in specific environments, particularly:

• Bedrooms
• Care homes
• Student accommodation
• Properties with increased fire risk

While not mandatory in all homes, AFDDs are strongly advised in many new installations and rewires. Their adoption is expected to increase as awareness grows.

Appliance-Related Fire Risks

Many domestic electrical fires originate from everyday appliances, including:

• Portable heaters
• Washing machines
• Tumble dryers
• Extension leads
• Older kitchen appliances

AFDDs are particularly effective at detecting faults within appliance flexes, which are a common source of hidden arcing.

Installation and Cost Considerations

AFDDs are typically installed within the consumer unit, often combined with MCB and RCD functions. While they cost more than traditional breakers, the added protection significantly reduces fire risk.

Installation must be carried out by a qualified electrician, as incorrect fitting can cause nuisance tripping or reduced protection.

Are AFDDs Worth It for UK Homes?

For older properties, homes with ageing wiring, or households with heavy appliance usage, AFDDs provide a valuable additional layer of safety. As UK homes become more electrically dependent, protection against arc faults is becoming increasingly relevant.

Conclusion

AFDDs represent a major step forward in electrical fire prevention. While they may not yet be standard in every UK home, their ability to detect faults that other devices miss makes them a powerful safety upgrade, especially in appliance-heavy households.