An arc fault circuit interrupter (AFCI) is a circuit breaker designed to prevent fires by detecting non-working electrical arcs and disconnect power before the arc starts a fire. The AFCI should distinguish between a working arc that may occur in the brushes of a vacuum sweeper, light switch, or other household devices and a non-working arc that can occur, for instance, in a lamp cord that has a broken conductor in the cord from overuse. Arc faults in a home are one of the leading causes for household fires.
AFCIs resemble a GFCI/RCD (Ground-Fault Circuit Interrupt/Residual-Current Device) in that they both have a test button, though it is important to distinguish between the two. GFCIs are designed to protect against electrical shock, while AFCIs are primarily designed to protect against fire.
The testing of AFCI's is a little more difficult as we need to simulate an arc. The MeasureSafe 36B has the ability to simulate an arc that the AFCI will detect as an arc profile and then trip. Only the trip time is measured as the arc current is of little concern. Extensive work has been undertaken to generate a simulated “faulty arc” current profile.