The National Electrical Code® (NEC®) has required Arc-Fault Circuit Interrupters in residential and limited commercial applications for many years, and they seem to expand requirements for every new Code cycle. There are receptacle based and circuit breaker based solutions. Each have their own unique advantages/disadvantages and applications. 

This blog isn’t about specific NEC requirements and where AFCIs are required.  There are enough videos and on-line instruction already available to address those concerns. Rather this blog is about how AFCIs function to help prevent electrical fires and the challenges electrical contractors face when installing them.  Nuisance tripping is the #1 complaint contractors have when installing AFCIs. After installation, homeowners may experience nuisance tripping when using a new vacuum cleaner or appliance. Then the contractor gets the call. The last thing they want to do is to go back for a warranty service call. 

To address this recurring issue the first thing contractors need to know is how and why AFCIs trip. AFCIs are a sophisticated piece of electronic equipment (almost like a computer) designed to detect arcing when a wire is punctured or damaged and when it does, cut power to the circuit. That’s how they help prevent electrical fires. The problem arises when an appliance or load is plugged into an outlet and its’ electrical signature is misinterpreted as an arc by the AFCI and the AFCI by design cuts power. Hence, nuisance trips. To address this problem, manufacturers of AFCI devices test many appliances known to cause tripping and record their electrical signature. That signature is logged into the memory of the AFCI device so it knows not to trip when that appliance is used.