The Importance of AFDDs (Arc Fault Detection Devices)

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Arc Fault Detection Devices (AFDD)

Arcs are visible plasma discharges caused by electrical current passing through a normally non-conductive medium such as air. This phenomenon occurs when the current ionises gases in the air, generating temperatures exceeding 6,000 degrees Celsius—high enough to start a fire.

An arc is created when electrical current bridges the gap between two conductive materials. The most common causes include worn contacts in electrical equipment, insulation damage, cable breaks, and loose connections.

Fire statistics show that in 2017/18, there were 74,118 primary fires, 13,070 of which were linked to electrical distribution or appliance faults—a significant figure. While AFDDs may not prevent all such incidents, they are likely to reduce fire occurrences. For this reason, installing AFDDs is highly recommended.

Waht are AFDDs?

AFDDs (Arc Fault Detection Devices) are protective devices installed in consumer units to safeguard against arc faults. They employ microprocessor technology to analyse the electrical waveform, detecting any unusual signatures that signify an arc in the circuit. This enables them to cut off power to the affected circuit, potentially preventing fires. Compared to conventional circuit protective devices, they are far more sensitive to arcs.

Like a Residual Current Circuit Breaker (RCCB) or Residual Current Breaker with Overcurrent protection (RCBO), AFDDs typically incorporate a test button that end users can operate to verify the device’s mechanical function.

In terms of physical size, MK Circuit Protection’s AFDDs are the same size as a standard circuit-breaker (whereas many AFDDs on the market are typically twice the size of a circuit-breaker and require a larger consumer unit for installation), so they do not need a larger consumer unit for installation.

Below IET introduce when and where we need to install an AFDD.Do I need to install Arc Fault Detection Devices?

The electrical designer/installer is best placed to offer advice on the installation of AFDDs.

In the current edition of the IET Wiring Regulations, BS 7671:2018, it is a recommendation to install AFDDs but the customer can choose to omit them. However, this decision should be based considering any relevant risk and safety factors against the cost of installation.

AFDDs are worth consideration if there is an increased risk of fire, such as:

  • Premises with sleeping accommodation, for example houses, hotels, and hostels.
  • Locations with a risk of fire due to the nature of processed or stored materials, for examplestores of combustible materials.
  • Locations with combustible constructional materials, for example wooden buildings.
  • Fire propagating structures, for example thatched buildings and timber framed buildings.
  • Locations with endangering of irreplaceable goods, for example museums, listed buildingsand items with sentimental value.

It may also be worth speaking to people insurance company, to see if they would pay out in the event of a fire if AFDDs were not installed as recommended in BS 7671:2018.

MK Circuit Protection’s AFDDs have safely protected a large number of circuits since 2021. If people would like to learn more about MK Circuit Protection’s AFDDs, please contact our sales team. For technical queries, please get in touch with our technical team. For more information on electronic products, please refer to the link below.

AFDD Archives – MK CIRCUITPROTECTION

Thanks for IET professional share. For more knowledge, can also visit https://electrical.theiet.org/courses-resources-and-career/free-resources/consumer-guidance/arc-fault-detection-devices/

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