Arc Fault Detection Devices (AFDD)

Arcs are visible plasma discharges caused by electrical current passing through a normally nonconductive medium. This is caused when the electrical current ionizes gases in the air. Temperatures created in this instance are sufficient to start a fire and cause extensive damage.

What Causes Arcs?

An arc is created when the electrical current jumps a gap between two conductive materials. The most common causes of arcs include worn contacts in electrical equipment, damage to insulation, break in a cable and loose connections.

What are Arc Fault Detection Devices?

AFDDs are protective devices installed in consumer units to provide protection from arc faults. They use microprocessor technology to analyse the waveform of the electricity being used to detect any unusual signatures which would signify an arc on the circuit. They are far more sensitive to arcs than conventional circuit protective devices.

In terms of physical size, Protek’s AFDDs are a single module device which, like a standard circuit-breaker, will fit a standard Protek consumer unit.


Do I need to install Arc Fault Detection Devices?

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 example, stores 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 buildings and items with sentimental value.

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

Do I need to install an AFDD on every circuit?

In some cases, it may be appropriate to protect particular final circuits and not others but if the risk is due to fire propagating structures, for example, a timber-framed building, the whole installation should be protected.

Protek's Range of AFDD

2 Pole 1 module 30mA Trip 'B' curve 6kA Type A AFDD for use with 35mm DIN rail. Compatible with all Protek enclosures and consumer units.

  • Voltage - 230V
  • Current type - 'A'
  • 2 Pole 1 Module 30mA 'B' Curve 6kA
  • Arc fault protection
  • Short circuit protection
  • Earth leakage protection
  • Max cable IN 25mm / OUT 10mm
  • Screw terminal clamp
  • Positive trap indication
  • Reset button  

Click here to view the AFDD range