What is a Ground Fault Circuit Interrupter (GFCI)?

A Ground Fault Circuit Interrupter is a device designed to protect people from electrical shock caused by ground faults. A ground fault occurs when current strays outside its intended path, such as through a person to the ground. GFCIs detect differences in current between the ungrounded (hot) and grounded (neutral) conductors, typically at a threshold of 4-6 milliamperes, and quickly disconnect the circuit.

GFCI devices are required in locations where the risk of electric shock is high, such as:

• Bathrooms
• Kitchens
• Outdoor receptacles
• Garages
• Crawl spaces

Note: This list is not all-inclusive. For a complete list of required locations, always refer to NEC 210.8.

What is an Arc Fault Circuit Interrupter (AFCI)?

An Arc Fault Circuit Interrupter is designed to mitigate the risk of fire caused by arcing faults. Arcing faults can occur when electrical wiring is damaged, such as from a nail piercing a cable, loose connections, or deteriorated insulation. AFCIs detect the unique signatures of hazardous arcing and interrupt the circuit before the fault leads to ignition.

NEC 210.12 mandates AFCI protection in various locations, including:

• Bedrooms
• Living rooms
• Dens
• Hallways

Note: This list is not all-inclusive. For a complete list of required locations, always refer to NEC 210.12.

Combination Ratings for AFCI Devices

The term "Combination" in the context of AFCI devices often leads to confusion. It does not mean the device combines GFCI and AFCI functions. Instead, Combination AFCIs are tested to provide protection against both series arcing faults (occurring within a single conductor) and parallel arcing faults (occurring between conductors).

This is an important distinction introduced by UL 1699 to ensure a higher level of protection against potential fire hazards. The term indicates the device’s capability to address multiple types of arc faults, not that it performs dual functions like protecting against ground faults.

Dual Function Devices: GFCI + AFCI

Dual Function devices combine both GFCI protection (for shock hazards) and AFCI protection (for fire hazards) into a single device. These devices are increasingly used to simplify installation while meeting the requirements of NEC 210.8 and 210.12.

Key benefits of Dual Function devices include:

• Reduced need for separate GFCI and AFCI devices in areas where both are required.
• Simplified wiring, especially in retrofits.
• Space savings in electrical panels.

It’s important to note that Dual Function refers to the simultaneous provision of both GFCI and AFCI protections, whereas Combination pertains specifically to the arc fault capabilities of an AFCI.

Dual Function vs. Combination: UL 1699 and NEC 210.12

UL 1699

UL 1699 establishes the performance and testing requirements for AFCIs. The term Combination AFCI under UL 1699 refers solely to the device's ability to detect and mitigate both series and parallel arcing faults. This term has no bearing on GFCI protection.

NEC 210.12

NEC Article 210.12 requires AFCI protection in dwelling units, particularly for branch circuits supplying outlets in designated locations. Where both AFCI and GFCI protections are required, the NEC allows the use of Dual Function devices to achieve compliance efficiently. However, the code does not use the term "Combination" to describe devices with GFCI and AFCI functionality; it reserves that term for the dual arc fault protection provided by AFCIs.

Practical Considerations for Installation

1. Panelboard Space: Using Dual Function breakers can save space in a panelboard by eliminating the need for separate AFCI and GFCI devices.
2. Compatibility: Not all electrical panels can accommodate Dual Function devices. Always verify compatibility with the panel manufacturer.
3. Troubleshooting: Dual Function devices provide diagnostic indicators, which help identify whether a trip is due to a ground fault or an arc fault, simplifying troubleshooting.
4. Code Compliance: Carefully review the NEC to determine whether both AFCI and GFCI protections are required for a given circuit. Dual Function devices can streamline compliance with such requirements.

Conclusion

Understanding the distinctions between GFCI devices, AFCI devices, Combination AFCIs, and Dual Function devices is essential for ensuring safety and compliance with the 2023 NEC. GFCIs protect against electric shock, AFCIs mitigate fire risks, Combination AFCIs address multiple arc fault types, and Dual Function devices integrate both GFCI and AFCI protections. By clarifying these terms and their applications, electricians can make informed decisions that enhance safety and streamline installations.

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