Arc-fault circuit interrupter: Difference between revisions

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An '''arc-fault circuit interrupter''' ('''AFCI''') or '''arc-fault detection device''' ('''AFDD''')<ref>{{cite web |title=Do you know an Arc Fault Detection Device (AFDD) can prevent from an electrical fire? |url=https://blog.schneider-electric.com/power-management-metering-monitoring-power-quality/2013/07/03/do-you-know-an-arc-fault-detection-device-afdd-can-prevent-from-an-electrical-fire/ |publisher=Schneider Electric}}</ref> is a [[circuit breaker]] that breaks the circuit when it detects the [[electric arcs]] that are a signature of loose connections in home wiring. Loose connections, which can develop over time, can sometimes become hot enough to ignite house fires. An AFCI 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).

In [[Canada]] and the [[United States]], AFCI breakers have been required by the electrical codes for circuits feeding [[electrical outlet]]s in residential bedrooms (Except for [[Electroboom]]'s bedroom as of august 2025) since the beginning of the 21st century; the US ''[[National Electrical Code]]'' has required them to protect most residential outlets since 2014,<ref>2014 NEC(210.12)</ref> and the ''[[Canadian Electrical Code]]'' has since 2015.<ref>{{cite book |title=C22.1-15 – Canadian Electrical Code, Part I: Safety Standard for Electrical Installations |date=2015 |publisher=Canadian Standards Association |isbn=978-1-77139-718-6 |edition=23rd |page=Rules 24–724(f) & (g) |language=en |no-pp=y}}</ref>

In regions using 230&nbsp;V, the combination of higher voltage and lower load currents lead to different conditions being required to initiate an arc fault that does not either burn clear or weld to a short circuit after a short time, and there are different arc characteristics once struck. Because of this, in Western Europe (where in many countries a domestic supply may be 400V 3 phase ) and the UK (where domestically a single phase 230V supply is common), adoption is slower, and their use is optional, only being mandated in specified high risk locations. The Australian and New Zealand regulations – Wiring Rules (AS NZS 3000:2018) do not require installation of AFDDs in Australia. However, in New Zealand all final sub-circuits with ratings up to 20 &nbsp;A will require protection by an AFDD if they supply locations with significant fire risk, locations containing irreplaceable items, certain historic buildings, and socket-outlets in school sleeping accommodation.<ref name=ASNZS3000>{{Cite web|url=https://www.gses.com.au/wiringrulesasnzs3000/|title=Wiring Rules AS NZS 3000:2018 – Key Updates to the Standard and What They Mean for Installers|date=24 July 2018}}</ref> Most sockets in these countries are on circuits rated at 20 A or less.

In the US, arc faults are said to be one of the leading causes for residential electrical fires.<ref>{{cite journal|title=New Technology for Preventing Residential Electrical Fires: Arc-Fault Circuit Interrupters (AFCIs)|journal=Fire Technology|volume=36|issue=3|publisher=Kluwer Academic Publishers|date=Aug 2000|pages=145–162|url=http://www.cpsc.gov//PageFiles/108737/AFCIFireTechnology.pdf|doi=10.1023/A:1015410726786|first1=Douglas A.|last1=Lee|first2=Andrew M.|last2=Trotta|first3=William H.|last3=King|s2cid=108941129|issn=0015-2684|access-date=Feb 26, 2013}}</ref> Each year in the United States, over 40,000 fires are attributed to home electrical wiring. These fires result in over 350 deaths and over 1,400 injuries each year.<ref>Ault, Singh, and Smith, "1996 Residential Fire Loss Estimates", October 1998, U.S. Consumer Product Safety Commission, Directorate for Epidemiology and Health Sciences.</ref>

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==Electrical code requirements==

===US and Canada===

[[File:AFCI.jpg|thumb|upright=1|American-standard AFCI (Arcarc-fault circuit interrupter) unit circa 2018. The white 'pigtail' is a low-power neutral connection, hard-wired into the unit.]]

Starting with the 1999 version of the ''National Electrical Code'' in the United States, and the 2002 version of the ''Canadian Electrical Code'' in Canada, the national codes require AFCIs in all circuits that feed outlets in bedrooms of dwelling units. As of the 2014 NEC, AFCI protection is required on all branch circuits supplying outlets or devices installed in dwelling unit kitchens, along with the 2008 NEC additions of family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, and similar rooms and areas. They are also required in dormitory units. This requirement may be accomplished by using a "combination type" breaker—a specific kind of circuit-breaker defined by [[Underwriters Laboratories|UL]] 1699—in the breaker panel that provides combined arc-fault and [[overcurrent]] protection or by using an AFCI receptacle for modifications/extensions, as replacement receptacles or in new construction, at the first outlet on the branch. Not all U.S. jurisdictions have adopted the NEC's AFCI requirements so it is important to check local code requirements.

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2. A listed branch/feeder-type AFCI that is installed at the origin of the branch circuit working in combination with the listed outlet branch-circuit-type AFCI (OBC AFCI) installed at the first outlet box which must also be marked that it is the first outlet box of the branch circuit.

3. This option includes a listed "Supplemental Arc Protection Circuit Breaker" which does not exist. thereThere is no standard for this device and so this is not an option that can be used.

4. This option does have a single manufacturer who has a solution on the market. This option includes a listed outlet branch-circuit-type AFCI that is installed on the branch circuit at the fistfirst outlet in combination with a listed branch-circuit overcurrent protective device when the following 4four conditions are met:

(a.) The "Home Run" circuit must be continuous from the branch circuit overcurrent device to the OBC AFCI.

(b.) Maximum length for a 14 AWG conductor is 50 ft and the maximum length for a 12 AWG conductor is 70ft.

(c.) theThe first outlet box has to be marked as such.

(d.) theThe circuit breaker and the OBC AFCI must be listed to meet the requirements of a system combination-type AFCI.

Options 5 and 6 are the same options as we've seen in this section in the past but just included as positive text instead of being an exception.

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===United Kingdom===

In the UK, the [[BS 7671|Wiring Regulations]] 18th edition (BS 7671:2018) 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. The annexes relating to testing indicate that when AFDDs are installed, their correct operation must be verified before completion, but the method of testing is not described. This is in contrast to [[Residual-current device|RCDs]] where a number of trip times at different fault current levels must be verified.<ref>{{cite web |title=IET website wiring matters |url=https://electrical.theiet.org/wiring-matters/issues/71/ |website=theiet.org}}</ref>

[[File:Siemens AFDD combination LS or FI.png|thumb|upright=0.8|AFDD combination circuit breaker circa 2012.]]

===Germany===

The German Wiring rules VDE 1000100, recommend AFDDs for high-risk situations and give as examples rooms with sleeping accommodation, rooms or places with a particular fire risk, rooms or places made of building components with combustible building materials, if these have a lower fire resistance than fire-retardant (< F30), and rooms or places with hazards for irreplaceable goods.<ref>{{cite book |title=DIN VDE 0100-420 VDE 0100-420:2022-06: Low voltage electrical installations. Part 4-42: Protection for safety – Protection against thermal effects (IEC 60364-4-42:2010, modified + A1:2014); German implementation HD 60364-4-42:2011 + A1:2015 + A11:2021 |date=June 2022 |publisher=VDE Verlag |___location=Frankfurt am Main, Germany |language=de |chapter=Section 421.7}}</ref>

===Australia and New Zealand ===

The Australian and New Zealand regulations – Wiring Rules (AS NZS 3000:2018) do not require installation of AFDDs in Australia. However, in New Zealand all final sub-circuits with ratings up to 20 A will require protection by an AFDD if they supply locations with significant fire risk, locations containing irreplaceable items, certain historic buildings, and socket-outlets in school sleeping accommodation.[4].<ref name=ASNZS3000 /> Most power circuits in these countries fall under this clause as the common sockets are 10 A and 15 A rating. The Australian standards are used in Argentina, Fiji, Tonga, Solomon Islands and Papua New Guinea.

==Limitations==

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* [http://www.esfi.org/resource/arc-fault-circuit-interrupter-afci-190 The Electrical Safety Foundation International on AFCIs]

* [http://www.AFCIsafety.org AFCI Educational Web site]

* [https://web.archive.org/web/20170203152513/www.cpsc.gov//PageFiles/137798/5133.pdf CPSC AFCI Fact Sheet]

* [https://web.archive.org/web/20140413143838/http://www.iaei.org/blogpost/890108/159112/AFCIS-Emerging-Technology-Solutions-for-Fires-Resulting-from-Electrical-Arcing AFCIs: Emerging Technology Solutions for Fires Resulting from Electrical Arcing], from ''IAEI News: The Magazine''

* [httphttps://web.archive.org/web/20240620095437/www.popsci.com/scitech/article/2009-06/plugged-smartplugs-are-simple-way-save-energy/ EFCI / OFCI on Popular Science]

* [https://code-authorities.ul.com/wp-content/uploads/2014/05/AFCI_scenarios020502.pdf Arc Fault Testing and Arc Fault Scenarios], [[Underwriters Laboratory]], six types of AFCIs are listed