CQD Spotlight features questions and answers from NECA and ELECTRICAL CONTRACTOR’s Code Question of the Day program.
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From the archives—April 10, 2023
I very much enjoy reading your daily questions and improving my electrical code knowledge. I often find myself anxiously waiting for the installment. I have an outdoor kitchen with an electric food smoker at my house. The smoker constantly trips my GFCI receptacle. I've had the same experience using different smokers and different GFCI receptacles. Is there an exception in the code that would permit the installation of a single dedicated receptacle, with an in-use cover without GFCI protection, as opposed to a GFCI-protected duplex receptacle for this type of use?
Glad to hear you enjoy the forum, and thank you for participating. There is no exception for the installation you described. It may be beneficial to contact the manufacturer of the GFCI devices you have used, informing them of the nuisance tripping issues. Most major manufacturers have a technical support contact phone or email, where a report of product issues can be documented, and in some cases solutions may be available.
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The question above highlights a situation that inspectors, installers and homeowners encounter: equipment that trips GFCI protection, even when installations fully comply with the National Electrical Code. The NEC does not provide an exception allowing the removal of GFCI protection because it trips on a load. Quite often, it trips for a good reason. Safety cannot be compromised for convenience.
However, this question provides an excellent opportunity to discuss an important advancement in GFCI technology that was a direct response to unwanted tripping due to the use of the equipment grounding conductor (EGC) for leakage currents and other uses for which it was not intended. In some cases, the EGC is the dumping ground for high-frequency leakage currents. Traditional Class A GFCIs are evaluated and calibrated based on 60-Hz sinusoidal leakage currents, but they respond to all currents that go outside of the normal path. For decades, this approach has been highly effective at reducing the risk of electrocution. The challenge today is that many modern appliances such as electric smokers, refrigerators, variable-speed motor-driven equipment and devices with switch-mode power supplies produce leakage currents that travel across the EGC, which happens to be outside of the normal path of current. These loads can introduce high-frequency components onto the grounding path, which a GFCI will detect and open.
Recognizing this mismatch between modern loads and legacy protection devices, enhancements were introduced to UL 943, Standard for Ground-Fault Circuit-Interrupters, which introduce a new GFCI classification: Class A-HF (high-frequency). A Class A-HF GFCI is still a Class A GFCI device, providing the same 4–6 mA personnel protection required by the NEC and OSHA, but it is additionally evaluated for immunity to high-frequency leakage currents up to 150 kHz. This allows the device to distinguish between hazardous ground faults and nonhazardous, high-frequency leakage produced during normal appliance operation.
From an NEC perspective, this distinction is critical. The code does not require a specific type of Class A GFCI—only that a Class A GFCI be installed. Because Class A-HF devices still meet the fundamental definition and performance requirements of a Class A GFCI, they can be installed today in any location where the NEC requires GFCI protection. This is true even ahead of explicit recognition in the 2026 NEC. It’s not different than a receptacle marked ”WR” for weather-resistant or a receptacle marked ”TR” for tamper-resistant. These are still receptacles and can be used anywhere a receptacle is required.
This advancement offers a practical, code-compliant option to address those applications where leakage currents are a challenge. Instead of seeking exceptions that do not exist, installers and homeowners can select a GFCI designed for compatibility with modern electronic loads—maintaining safety while reducing unnecessary interruptions.
As electrical systems continue to evolve, solutions like Class A-HF GFCIs demonstrate how standards and products can adapt without compromising the life safety principles that remain at the core of the NEC.
