Q&A for How to Determine when to Use Arc Fault Circuit Interrupters (Af Circuit Breakers)

AFCI circuit breakers need to be installed in the circuit breaker or service panel. If your dwelling has armored cable or pipe from the service panel to the first box, and that first box is constructed of metal (not plastic or fiber), you can remove the receptacle and replace it with an AFCI receptacle. If the first box does not contain a receptacle (is a switch or ceiling box of a fan or light) it will not be possible to install a receptacle in those boxes and will require that an AFCI breaker be installed in the electric panel instead.

Be careful, regular breakers do not monitor the neutral wire from that circuit. You must remove the neutral from the neutral bar and land it on the arc fault breaker so that it will now monitor the current peaks, and will shut the circuit off then it senses a problem.

It depends on local ordinances. Here in San Antonio, what you just described would be a violation of our local code, because nothing smaller then #12 wire is acceptable. Just remember, a 20 amp breaker is for wire rated for 20 amps, hence the #12. If the code allows #14 wire then you must protect it with a 15 amp breaker.

AFCI is required in dwelling units only (commercial and industrial locations are not required to have this protection). A dwelling unit is defined by the NEC as: "A single unit providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation." A detached garage does not meet this definition, and therefore is not required to have AFCI protection. Of course, the local AHJ may require it, so checking with him/her can't hurt. Swapping standard circuit breakers to AFCI combination breakers is easy to do though.

Any normal household light switch should not trip an AFCI unless there is a serious problem with the switch.

Each 120 volt circuit (black / red hot wire and white neutral wire) is connected to the respective terminals ON the AFCI device for the circuit. For this reason, a fault on one AFCI should not cause any other AFCI devices in the panel to open. Make sure both hot AND neutral conductors of the branch circuit are connected to the correct terminals on the AFCI. (Do NOT connect the branch circuit neutral wire to the neutral bar in the panel.) The curly white pigtail wire that is factory connected to the AFCI must be connected to the neutral bar in the panel.

Yes. Branch circuit conductors can be spliced, neutral and or line (hot). Since AFCIs are installed on 120 volt circuits rated at 20 amps or less, all of these circuits are considered branch circuits.

They start at around $30 but can go much higher. A 20 amp Murry brand AFCI is $39 at Home Depot.

AFCI (arc fault circuit interrupters) devices are installed in the electrical panel. GFI (ground fault interrupters) are available in a circuit breaker package (called a combo device - circuit overload and ground fault protection) and an outlet package. GFI is designed to protect people, not property or short circuits - except in the case of the combo device.

Since AFCI protection is not required for circuits that supply more than 20 amps, it is unlikely that AFCI breakers larger than that will be made available by manufacturers.

Yes. If code is calling for a service upgrade, that will include all of the components of the attached panel, including breakers.

Yes. You should be able to find 30 amp GFCI breakers in single pole and two pole.

This is generally the case, yes. However, you should first check with the AHJ to be sure.

The AHJ is your guide here. In many places, it has been determined to be unreasonable to require that an existing installation (installed to then-current code regulations) be brought to current code standards when there is less than a 50% renovation.

Use a dual-function breaker, it offers both AFCI and GFCI protection. You could also use an AFCI breaker and place a dead-front GFCI over the dishwasher above the counter.

Yes. Install the AFCI breaker in the panel and replace the first receptacle with a GFCI type; be sure to land the supply wires on the line terminals and the wires that feed the downstream receptacles on the load terminals.

You may be overloading the circuit. A typical refrigerator uses approx 615 watts, a computer 300 watts, and a home use printer 50 watts.

Yes, if you are modifying or extending the existing circuit or installing a new one, or replacing a receptacle on that branch circuit, and it is 120 volts and either a 15- or 20-amp circuit, unless local rules have been modified. NEC(2017):210.12(A).

Yes, it requires AFCI protection for a "120-volt, 15- or 20-amp branch" serving "outlets or devices in dwelling unit kitchens" specified in NEC 210.12(A) and GFCI protection under NEC 210.8(D)., 2017 edition.

This could be loose connections (panel, receptacle outlets at screw or back-stabbed), a foreign body penetrating the wiring (romex staple, nail, screw), faulty AFCI breaker, faulty appliance (microwave in your example). Like the GFCI, the AFCI has micro electronics on board that can go bad from excessive heat, current (indirect lightning strikes), floating service neutral (a leg exceeds 150v peak-to-peak). Consult your certified and bonded electrician for his/her expertise and skillset. Electricity is not the domain for a non-electrician handyman or DYI property owner.

Yes, if it is going to be used in kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas.

Not by the National Electrical Code, but your state or locals may adopt amendments that change it. The NEC only requires them on 15- or 20-A branches serving kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas.