Arc-fault circuit interrupters (AFCIs) serve an important role in building construction by preventing electrical fires. In this, AFCI electronics differ from ground-fault interrupters (GFCI) designed to prevent electrical shocks. This is an important and notable difference because they are two different types of hazards, and AFCIs use a different detection system. While a GFCI is designed to detect a ground fault before engaging, an AFCI instead detects arc faults.
About Arc Faults
Parallel Faults: This fault involves the hot conductor and the return conductor. The root cause is often a screw or a nail that inadvertently pierces your cables, often resulting in damage to both conductors or a partial grounding of the hot wire. Where the AFCI comes in is that it can detect this incorrect electrical pattern and the associated increased heart. This type of fault is often more dangerous than a total short.
Partial Faults: This type of fault involves the misplaced screw or nail piercing your wiring, but the current conductor is not severed. It causes components to overheat, but there is never a current overload, making this type of fault dangerous and hard to detect. An AFCI guards against this particular issue.
Loose Wires: Arc faults can be caused by loose wiring. Connections and wiring must be properly tightened to the correct torque to ensure safety. It is also important to note that wires should not be over-tightened as this can cause damage which leads to permanent electrical issues.
Other Wiring Concerns
In many buildings, the electrical system will use many splices and terminations to effectively power the entire structure. This has the unfortunate side effect of creating several possible points of failure due to loose wiring or wiring that has been over-tightened. Installation of AFCIs addresses this hazard. AFCIs monitor the current waveform of your electrical circuits, looking for signs of an arc fault and cutting the electricity to prevent dangers such as shorts or electrical fires.
AFCI Notes and Tips
AFCIs are available in breaker and receptacle formats just like GFCIs, and provide downstream protection. AFCIs, when installed, allow any downstream protection against arc faults. While this does allow for proper monitoring, it does not protect the wiring, and the wiring itself must be properly and safely installed. AFCIs also come equipped with reset and test buttons which allow for proper configuration. AFCIs are not sensitive to low voltage; however, they can be prone to false alarms during situations such as electrical storms, so it is essential to carefully monitor your devices.