Arc Fault Detection Devices

Most people know circuit breakers and fuses. Quite many also know ground fault circuit interrupter (GFCI) or Residual Current Device (RCD). But now a new protective device is coming to use in Europe and you might want to learn about it.  AFDD/AFCI Arc Fault Protection Device protects people and property against fires caused by arc flashes. An arc-fault circuit interrupter (AFCI) also known as an arc-fault detection device (AFDD) is a circuit breaker that breaks the circuit when it detects an electric arc in the circuit it protects to prevent electrical fires.

AFCI breakers have been required for circuits feeding electrical outlets in residential bedrooms by the electrical codes of Canada and the United States since the beginning of the 21st century; the U.S. National Electrical Code has required them to protect most residential outlets since 2014.The electronics inside an AFCI breaker detect electrical current alternating at characteristic frequencies, usually around 100 kHz, known to be associated with wire arcing, which are sustained for more than a few milliseconds. As of January 2008, only “combination type” AFCIs meet the NEC requirement. The downsides of AFCIs are that they do not protect against all kinds of faults and AFCIs are also known to be sensitive (false tripping) to the presence of radio frequency energy.

Now the use of AFDD is also noted and recommended on Europe.  The international standard IEC 60364-4-42:2010+A1:2014 and European standard HD 60364-4-42:2011+A1:2015 highly recommend using arc fault detection devices and consider them as the state-of-the-art devices in this area. According to IEC 60364-4-42 the installation of arc fault detection devices (AFDDs) is strongly recommended in many applications. The device is expected to attract particular interest from the residential sector. In the UK the 2018 edition of the wiring regulations is the first edition to make any mention of arc fault devices, and indicate they may be installed if the design has an unusually high risk of fire from arc faults.

AFDD is available as separate protective device and also as arc fault detection circuit breaker (MCB + Arc Fault Detection unit) that fits into a standard electrical panel.  Both are designed to disconnect power before an electrical fire starts.

Arc fault detection device (AFDD) – recommended acc. to IEC standard

Let’s dig deeper in what those AFDD devices are and how they work. AFDD  device tries to detect high frequency patterns on an electrical circuit that indicate an imminent arc flash and activates a trip switch to eliminate the risk. An AFDD/AFCI needs to selectively distinguishes between a harmless arc (incidental to normal operation of switches, plugs, and brushed motors), and a potentially dangerous arc (that can occur, for example, in a lamp cord which has a broken conductor). AFDD is designed to protect against three types of arc faults: Series fault arcs (conductor break or loss of contact in series with a load), parallel fault arcs L-N and parallel fault arcs L-PE.

AFDD – Arc Fault Detection Device – Part 1

AFDD Arc Fault Detection Devices Additional Tests (Part 2)

AFDD Regulations in BS7671, Other Information (Part 3)

The Arc Fault Detection Device (AFDD)

Arc Fault Detector / Demonstrator

ABB AFDD testing

Finally let’s take a look inside.

AFDD open box


  1. Tomi Engdahl says:

    Western Automation Arc Fault Protection Demonstration

    Western Automation Arc Fault Protection Demonstration

  2. Tomi Engdahl says:

    The difference between a circuit breaker and an arc-fault/ground-fault circuit breaker

    In this simple demo conducted at Eaton Corp.’s Power Systems Experience Center, Dan Carnovale explains what an arc fault is and why there is such a big deal made about detecting arc faults in circuits. Also explained are the components added to an ordinary circuit breaker that go into detecting both arc faults and ground faults.


    Well they cause problems in older homes. They are required in California and they are great for new homes but a lot of older homes trip them constantly when retrofitted. Most cities will allow you to go without them.

  3. Tomi Engdahl says:

    Arc Fault Circuit Interrupter

    A new type of electrical protection device is available to do a different function than either a circuit breaker or a ground fault circuit interrupter. This video introduces that device and compares its function and necessity to the previous two.

  4. Tomi Engdahl says:

    Dual Function AFCI/GFCI Circuit Breaker | Volt Stream Video Series

    Dual Function AFCI/GFCI Circuit Breaker
    Two state-of-the-art technologies combined in one device

  5. Tomi Engdahl says:

    John Ward Talks New Consumer Units, RCD’s, SPD’s and AFDD’s LIVE to the Learners of Tresham College

    To a live audience at Tresham College John Ward (JW) talks about new consumer units, RCD’s, SPD’s and AFDD’s.

  6. Tomi Engdahl says:

    Insulation resistance and RCDs

    Tracing the troublesome tripping of an RCD!

    A closer look at how poor insulation resistance on final circuits affects an RCD, and how detecting poor insulation resistance can point you to the problem.

  7. Tomi Engdahl says:

    MCG Arc Fault Detection Device & General AFDD Info

    Another AFDD, this one is a single full height module with permanently connected neutral. MCG Industrial, available from CEF. Also a look at the documents supplied with it, which cover general AFDD information.

  8. Tomi Engdahl says:

    Four AFDDs Compared – Arc Fault Detection Devices

  9. Tomi Engdahl says:

    AFDD Regulations in BS7671, Other Information (Part 3)

  10. Tomi Engdahl says:

    The Arc Fault Detection Device (AFDD)

    All about the AFDD (or AFCI).
    Also available in article form on my website with some updated information:

  11. Tomi Engdahl says:

    Arc Fault Detection Devices (AFDD) From Wylex Practical Demonstration (18th Edition BS 7671)

    AFDD identify dangerous faults caused by arcing in electrical circuits and are designed to switch off the circuit before a fire occurs. Under the 18th Edition of the Wiring Regulations and beyond wider use of these types of devices is expected. This video shows a practical demonstration of an AFDD clearing an arc fault in circuit,

  12. Tomi Engdahl says:

    The arc fault detection device (AFDD) S-ARC1

    The arc fault detection device (AFDD) S-ARC1 provides maximum safety in the electrical installation of all buildings, thus protecting people and valuable assets. By early detecting arc faults and disconnecting the affected circuit the AFDD offers reliable protection with easy installation, bridging the gap of series arc faults which cannot be detected by MCBs.
    Combined with a Residual Current Circuit Breaker (RCCB) as upstream device, the S-ARC1 series provides the best solution for complete protection in the switchboard.

  13. Tomi Engdahl says:

    Arc Fault Detection Devices (AFDDs) #e5 Vienna Visit to Eaton’s Test Centre to Validate AFDD’s PT 1

    So the two Pauls took a trip to Vienna to the R&D labs of Eaton to gain assurance, learning, and confidence in what is new to the UK in AFDD devices.

  14. Tomi Engdahl says:

    Arc Fault Detection Device, Circuit Protection | Eaton

    Eaton AFDD+ – Incorporating the next generation of detection technology, the Eaton AFDD+ provides enhanced fire protection, what reduces the risk of electrically ignited fires, by detecting arc fault currents other protection devices can’t.

  15. Tomi Engdahl says:

    AFDDs & BS7671 Amendment 2 – What you need to know!

    The latest version of IET wiring regulations BS7671 Amendment 2 is now a requirement for new UK electrical installations. One of the major changes is the mandatory use of Arc Fault Detection Devices AFDDs in certain types of buildings and applications.

    BS7671 AMD2 Effective date 28th September 2022

    In partnership with Lewden Palazzoli, we’ve produced this training module to help update electricians, specifiers and electrical wholesalers.

    For more FREE Training modules, checkout eFIXX Know How
    00:00 AFDDs
    00:39 Content elements
    01:11 Circuit protection
    01:50 Overload
    02:07 Short circuit
    02:35 Old fuses
    03:03 Insulation
    03:35 RCD
    04:07 Arc faults
    05:34 Series and parallel arcs
    06:11 What is a parallel arc
    06:57 Exception to the rule
    07:54 Protection for the pugged in load(s)
    08:25 AC waveform
    08:37 Arc fault waveform
    08:53 Inside an AFDD
    09:40 Will sparks cause an AFDD to trip
    10:44 Overvoltage protection
    10:57 Do I still need a type 2 SPD
    12:40 Self-test function
    13:33 The LED on the AFDD
    14:06 What the Regs say about AFDDs
    16:00 What does recommend mean

    Complete the AFDD CPD training module


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