What Is an Arc Fault and How Do I Prevent It?

Wondering what is an arc fault? When unplugging your iron, you may have seen a spark that comes from the electrical outlet. Or maybe you’ve been dumbfounded by a light switch in your home that makes an unusual buzzing or hissing sound. Such occurrences are no accident; rather, they’re the result of what is known as an arc fault. If you recognize damage from an arc fault, consult a local electrician to determine the cause and best next steps.

What Is an Arc Fault? 

An arc fault occurs when loose or corroded wires come in contact, causing an electrical current to spark, or arc, as the metal wires touch. Arcing generates high-intensity heating, which can wear down the wire’s insulation and cause electrical fires. For this reason, arc faults are considered a dangerous electrical problem. When wires are damaged, overheated, stressed, or compromised in some way, arc faults are a likely result. 

Arc Fault vs. Short Circuit vs. Ground Fault: What’s the Difference?

An arc fault is often incorrectly interchanged for a short circuit or ground fault—two other hazardous electrical occurrences requiring prevention. However, it’s important to note that these terms are different, thus also requiring different preventative measures. 

A short circuit results from an electric current traveling down a shorter, unintended route rather than its intended path. Short circuits can cause fires, electrical burns, and electrocution, all of which can cause serious injury and even death. 

A ground fault occurs when electricity flows through an unintended path in trying to reach the ground. While shock is the most common danger, ground faults can cause fires and burns. 

While an arc fault can eventually result in a short circuit or ground fault, it’s a phenomenon entirely of its own. And since it may not shut down a ground fault circuit interrupter (GFCI) or a circuit breaker, other safety precautions are needed to prevent arcing.

How to Use AFCI Protection

Beginning in 1999, the National Electrical Code (NEC) required that AFCI protection be installed in all circuits connected to bedroom outlets. By 2014, the mandate was updated to require that all circuits connected to living spaces have AFCI protection. 

Arc fault circuit interrupters, or ACFI, are protective devices that prevent faulty connections that cause arcing. In the event of an electrical arc, such devices break the circuit and stop electrical fires. AFCI protection usually comes in the form of a circuit breaker that protects outlets and devices along the circuit. However, there are also ACFI outlets available when breakers cannot be used. 

Why AFCI Should Not Replace GFCI

GFCIs are designed to prevent shock while AFCIs guard against fires. That’s why one type of protection should never replace the other. On the contrary, you should use both in your home to provide arcing fault protection and ground fault protection. The most common way to do this is to use an ACFI circuit breaker and a GFCI receptacle. Keep in mind the importance of maintaining both types of features to protect your home from an electrical emergency.