Get to know AFCI outlets and how Arc Fault Circuit Interrupters deliver safer electrical services to your home
First let's take a quick look at what an AFCI receptacle is and how it's different form the GFCI Outlets that we all know.
The Difference between AFCI outlets and GFCI Outlets
The main difference between AFCI and GFCI outlets are what they are designed to protect against. GFCI style receptacles are outlets designed to prevent electric shock and accidental electrocution. The acronym GFCI stands for Ground Fault Circuit Interrupter. It's purposefully designed to “trip” or toggle off when it detects that the electrical current is flowing through an unintended source, such as liquid, or the human body. Because of the increased risk of electric shock and electrocution that occurs when an electric current comes into contact with liquid, GFCIs are required by code in Minnesota to be installed in rooms, where liquids are present (Kitchen, Restroom...)
The outlet itself looks much like a typical power outlet, except for the addition of two control buttons marked "Test" & "Reset. The reset button is designed to reset or reactivate the outlet after it has been tripped. The test button will test to make sure the GFCI is actually working. If the GFCI outlet is working properly as designed, pressing the test button will cut power to the outlet, and whatever you have plugged into the outlet, will not turn on. The reset button will return normal power supply back to the outlet, after it has been tripped (or after using the test button).
So now that we have looked at GFCI outlets, let’s take a look at AFCIs.
What is an AFCI?
AFCI stands for Arc Fault Circuit Interrupter. While the GFCI is designed to protect against shock and electrocution, AFCI recepticals / outlets are designed to protect against fires caused by rapid escalations of electric power known as "electrical arcs". Electrical arcs can cause overheating and electrical currents to spill out from their intended pathways which can lead to fires. Electrical arcs are one of the main causes of electrical fires, and electrical fires are the main causes of property fires period, so the importance of AFCIs cannot be overstated.
AFCIs may not be always as obvious as GFCIs. While they may have reset and test functions easily accessible through the outlet faceplate, the AFCI device may be under the faceplate. AFCI outlets are required in all rooms that are primary areas of residential dwelling (think all of the places in your home that your family spends time in: bedrooms, dens, living rooms, family rooms, dining rooms..(well let's be honest - how much time do you actually spend in that beautiful formal dining room...but still: Be Safe and add them their as well. The concept of how AFCIs work is similar to how GFCIs work. When the AFCI senses a power arc, it trips the normal supply of power to the outlet to shut off the power in much a similar way that a circuit breaker switches.
Options for AFCI type receptacles are growing. Requirements for residential arc-fault circuit-interrupters (AFCIs) were first mandated in the 1999 National Electrical Code (NEC) and their application has been expanded in every code cycle since. Until recently, installers have had to rely on circuit breaker type AFCI devices to address these requirements. Now it's far more accessible at the outlet or receptacle level to add these Minnesota Code Compliant AFCI outlets.
The actual operation of an AFCI is sometimes misunderstood. Unlike ground-fault circuit-interrupters (GFCI) that provide fatal electrical shock protection to people by detecting leakage current and quickly disconnecting power, AFCIs protect structures from fires and related hazards by detecting arcing and quickly interrupting the power in the circuit. Since the wires are in the wall, it's nice to know that your home and family have an additional layer of protection to mitigate loss, injury, house fires, and failing electrical equipment.
AFCI devices are designed to detect two types of ARC faults: Series Arc Faults and Parallel Arc Faults.
What is a Parallel Arc Fault: Parallel arcs also occur due to a break, yet electrically jump between line, neutral or ground.
New AFCI outlets addresses the dangers associated with both Series Arc Faults and Parallel Arc Faults. Similar to GFCI devices, AFCI receptacles provide feed-through protection and are able to detect downstream arc-faults, both parallel and series, as well as upstream series arc faults. (protecting the outlet at the outlet with an eye on the overall electrical system.
Effective Jan. 1, 2014, NEC Article 406.4 will require that where a receptacle outlet is supplied by a branch circuit that requires AFCI protection according to 210.12(A), a replacement receptacle at this outlet may be one of the following:
• a listed OBC type AFCI receptacle,
• a receptacle protected by an upstream listed OBC type AFCI receptacle, or
• a receptacle protected by a combination (series/parallel) type AFCI circuit breaker.
Early proposals for the 2014 NEC suggest an expansion of the AFCI branch circuit protection requirements to include the kitchen and laundry areas of a dwelling. In addition, changes will allow AFCI receptacles to be installed with standard nonmetallic-sheathed (NM) type cable to protect the entire branch circuit in any of the areas specified in Article 210.12 (A) with the following caveats:
AFCI receptacles must be installed as the first outlet on the branch circuit, that first AFCI receptacle must be within 70 feet of the overcurrent protection device for 12 gauge conductors and within 50 feet of the 14 gauge conductors, and AFCI receptacles must be listed for compatibility with specific magnetic circuit breakers commonly found on the market today or used downstream from a new type of breaker called a supplemental arc protection (SAP) breaker that enhances the parallel arc protection close to the overcurrent device.