Tech Talk – How AFCIs Help Protect Your Home from Electrical Fires

How AFCIs Help Protect Your Home from Electrical Fires

The Consumer Product Safety Commission estimates more than 50% of electrical fires that occur every year could be prevented by Arc Fault Circuit Interrupters (AFCI)*.  That’s an important statistic worth paying attention to for the improved safety of your family and home. But, what exactly is an AFCI and how does it work?

An AFCI is an electrical device designed to help prevent electrical fires that can be caused by potentially dangerous arc-faults in an electrical circuit. Leviton Outlet Branch Circuit (OBC) AFCI Outlets provide this important protection at the outlet level, making them easy to install and easy to reset should the device trip.

What is an Arc-Fault?

Let’s start with a brief primer on what an arc-fault is.  An arc-fault is a potentially dangerous electrical problem caused by damaged, overheated or stressed electrical wiring or devices.  Arc-faults can occur when older wires become frayed or cracked, when a nail or screw damages a wire behind a wall, or when outlets or circuits are compromised.

Arc Fault Causes

OBC AFCI outlets contain electronic components that constantly monitor a circuit for the presence of “normal” and “dangerous” arcing conditions.  Based upon an established threshold of arc energy, the OBC AFCI can be triggered to quickly react and cut power if “dangerous” arcing is detected.  It is important for all residents of a home to understand the difference between “normal” arcing, which is normally safe, and “dangerous” arcing.  Below are a few typical examples of each:

Low Energy/Operational Arcs – Typically Safe

  • Naturally occur when contact or switch opens/closes
  • When a motor with brushes runs
  • Generated by household appliances such as refrigerators, air conditioners, tools, or fans

High Energy/Hazardous Arcs – Potentially Dangerous

  • Should not occur or should be safely contained
  • When insulation on a wire has been damaged
  • Loose connections that expose wire
  • Loose connections where wires separate causing an arc to jump from one place to another

The images below depict potentially dangerous arcing:

Parallel Arc Fault  Series Arc Fault

OBC AFCIs are engineered to sense minute, fleeting fluctuations in the frequency and amplitude of the electricity’s 60-cycle-per-second waveform. Such fluctuations occur all the time when current flows. The key is their ability to differentiate between the common background fluctuations and detect only the ones that exhibit the signature of a dangerous arc fault —either a parallel arc fault between two conductors, or a series fault where there’s a break in a single conductor as seen in the image above.

AFCI Protection

When installed as the first outlet on a branch circuit, OBC AFCI outlets provide series arc protection for the entire branch circuit. They also provide parallel arc protection for the branch circuit starting at the OBC AFCI outlet. OBC AFCI outlets may be used on any wiring system regardless of the load center and for this reason are ideal for older homes, which often have load centers that may not be compatible with AFCI circuit breakers.

Learn more about AFCI Protection from Leviton

* Economic Considerations – AFCI Replacements. Memorandum. United States Consumer Products Safety Commission, March 2003.