Prevent Fires Before They Start: The Critical Role of Arc Fault Detection Devices (AFDDs) in Electrical Safety

Why AFDDs?

Did you know that a significant number of building fires are sparked by faults in electrical installations?


Aging cables, improper installation, or even a nibble from a curious rodent can damage cable insulation, leading to arc faults. These dangerous discharges of electricity between wires generate intense heat, posing a serious fire risk if not swiftly interrupted.


This is where Arc Fault Detection Devices (AFDDs) become your silent guardians. By instantly detecting arc faults and cutting off the power, AFDDs minimize the risk of fire by immediate detection of arc faults, safeguarding both your property and lives.


Arc Fault Detection Devices (AFDDs) are crucial in places with a high risk of electrical fires, such as premises used for sleeping and accommodation. These include hotels, hospitals, houses, hostels, and apartments. Such buildings often contain personal belongings that are highly combustible and can be easily destroyed by fire. Therefore, AFDDs are widely applied in the electrical installation systems of these premises to enhance safety and prevent fire hazards. If you are living in such buildings, ensuring the presence of AFDDs can significantly reduce the risk of electrical fires.


The IET Wiring Regulations, BS 7671: 2018 regulations 421.1.7 states the following:


Arc Fault Detection Devises (AFDDs) conforming to BS EN 62606 shall be provided for single-phase AC final circuits supplying socket-outlets with rated current not exceeding 32A in:

  • Higher risk Residential Buildings (HRRB)
  • Houses in Multiple Occupation (HMO)
  • Care homes

Types of ARCs

Parallel Arc Fault

A parallel arc fault occurs when two power phases or a power phase and ground are close together. This typically happens when insulation material is degraded or contaminated. Loose connections in the circuit or loose screw rivets on the busbar can also cause parallel arc faults.

Series arc fault

A series arc fault occurs when there is a loose connection between terminals and the cord in the circuit, causing it to be in series with the current load. Incomplete cord connections can also generate this fault. These conditions increase contact resistance, leading to the generation of high-temperature arcs, especially if the potential difference across the circuit is high.

How AFDDs Work

Conventional protective devices like Miniature Circuit Breakers (MCBs) and Residual Current Devices (RCDs) often miss arc faults, which can lead to fires. Arc Fault Detection Devices (AFDDs) are designed to detect these dangerous arcs. An AFDD is equipped with a digital microcontroller and advanced electronics to continuously monitor the power waveform in the circuit. It compares the observed waveforms to known safe patterns. When it detects a waveform typical of an arc fault, the AFDD immediately interrupts the power flow, preventing potential fires and ensuring safety.


While MCBs and RCCBs are crucial for protecting against overcurrent, short circuits, and earth faults, AFDDs provide an additional and essential layer of protection by detecting and preventing arc faults, which are a common cause of electrical fires. By integrating AFDDs into electrical systems, especially in high-risk areas, you can significantly enhance overall safety and reduce the risk of fire, offering comprehensive protection for both property and lives.

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