October 14, 2016

How To Choose Whether GFCI Or AFCI

Know if you need GFCI and AFCI outlets

GFCI (ground fault circuit interrupter) outlets protect you from electrocution. They contain a small circuit breaker that trips if it detects a short circuit. AFCI (arc fault circuit interrupter) outlets help protect your home from electrical fires. Similar to GFCI outlets, AFCI outlets contain a small breaker that trips when it detects a dangerous arc. (Electrical arcs create heat that can light insulation, framing and other building materials in your home.)

GFCI and AFCI explanation.

Ground Fault Circuit Interrupters VS Arc Fault Circuit Interrupters

GFCI and AFCI protection have both become fundamental safety devices in electrical systems. Understanding the basics of ground-fault protection for people, and arc-fault protection for 15- and 20-amp branch circuits in dwelling units can ensure that your installations are code-compliant and help you in troubleshooting a circuit. As of the time this article was written (late January 2012), the NFPA code-making panels have met to consider proposals for the 2014 NEC. While the 2014 NEC code development process still has a long way to go, a number of GFCI and AFCI proposals are in the works, once again revising where these devices get installed. We’ll discuss a few of them along with some product standard and technology changes.

Ground-Fault Circuit Interrupter (GFCI). A device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a Class A device.

How does a GFCI work?

The operation of a GFCI is really quite simple. It compares the amount of current going out to the load with the amount of current coming back from the load. In a single-phase device both the hot and neutral conductors pass through a current transformer (CT). This is why the load neutral conductor must be connected to a GFCI circuit breaker. If the current going out to the load equals the current coming back, there is no leakage to ground and the output from the CT is zero, but if there is an imbalance, an electronic circuit will determine if the leakage is enough to necessitate an interruption of the current flow.

Arc-Fault Circuit Interrupter (AFCI). A device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected.

How does an AFCI work?

The operation of an AFCI is far more complex than that of a GFCI. Unfortunately, there is no single characteristic that is unique to hazardous arcs, so an AFCI must look for multiple characteristics, usually occurring at the same time or within a short period of time, to determine whether or not to interrupt the current flow. This usually involves monitoring both the current and the voltage.

The Importance Of GFCI And AFCI Breakers

GFCI’s trip when they sense a short to ground by measuring the difference in current between the line and neutral of the circuit. These can prevent electrical shock when water presents an opportunity for a short. AFCI breaker trips when it senses low or high current arcs that can be caused by damaged wiring or loose connections which can cause fires.

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