Update: Resolving the GFCI Nuisance Trip Issue for HVACR
Recently ACCA and an industry coalition successfully convinced the National Fire Protection Association Standards Council to approve an exception to the National Electrical Code (NEC) regarding the requirement for a ground-fault circuit interrupter (GFCI) device for outdoor equipment. The new exception to 210.8(F) exempts listed outdoor HVACR equipment from having to comply until September 1, 2026. This change was approved for the existing 2020 NEC and also appears in the newly published 2023 edition. However, when the above date expires, what then? There’s a lot going on in the new year to prepare for the expiration date, so read on.
How We Got Here
Over the past few code change cycles (they occur every three years), the NEC was revised to expand the applications requiring GFCIs for personnel protection to mitigate the risk of electric shock. The application of GFCI devices in the 2020 NEC was expanded to include outdoor heat pumps and air conditioners. However, when GFCIs were installed on such equipment in the field to comply with the new code, it created numerous nuisance trips, rendering the equipment inoperable. This occurred primarily in early adopting states like Minnesota and Texas. The prevailing theory is that the tripping may be caused by high-frequency harmonic signals emitted by nonlinear electrical loads, such as variable speed drives or frequency inverters. This technology is becoming more prevalent for heat pumps and air conditioners complying with the new Department of Energy (DOE) efficiency standards, which took effect on January 1 of this year.
Fixing the Code: NEC 2026
The ink is barely dry on the 2023 edition and now a new NEC code change cycle has begun. We must work fast not only to find and verify the cause of the nuisance trip problems in the field but also to propose solutions for the relevant safety standards and potentially for the NEC itself. In order to provide our industry’s input to the upcoming NEC code cycle, ACCA and other industry allies applied for voting membership on the NEC Code-Making Panel 2, which is responsible for the GFCI coverage in the NEC.
Standards Activities Related to GFCI Issues
Several UL standards address the electrical incompatibility issues between HVACR equipment and Class A GFCI devices. On the equipment side, there is UL 60335-2-40, which is the safety standard for electric heat pumps and air conditioners. Current proposals seek to distinguish between the terms “leakage current” and “touch current,” which is defined as the electric current through a human body when it touches one or more accessible parts of an installation or equipment. Another proposed option provides a dual “protective earthing conductor” system with a monitoring device that interrupts all supply conductors when it detects an open circuit on the protective earthing conductors. It is believed that this latter feature is intended to be utilized in lieu of a GFCI device. In addition, the UL 101 Standard for Leakage Current for Utilization Equipment has recently proposed a “GFCI Interoperability Test.” This test is intended to evaluate the appliance’s ability to operate as intended on a circuit that is protected by a Class A GFCI. Currently, this investigation has been focused only on household appliances, and other types of permanently connected products, such as 240 V HVAC equipment, have not yet been studied. It is expected that the UL 101 proposals will ultimately be coordinated with the other UL standards, such as UL 60335-2-40 and the UL 943 standard for GFCI devices.
GFCI Research Project
In response to the nuisance tripping issues, the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) began a research project last year to find and document the causes of the problem. The research is being conducted by the Electric Power Research Institute (EPRI). Phase 1 of the project has been completed, and a report is expected sometime this spring. Once the problems have been identified and verified in the laboratory, the research is expected to determine proposed technical solutions, coordinate those solutions with the above-mentioned UL standards groups, and potentially support additional proposed changes to the NEC.
Other Nuisance Tripping Problems
ACCA is investigating other nuisance tripping issues created by Class A GFCI devices, which are required on basement receptacles per the NEC. One example is condensing furnace condensate pumps located in basements, which according to contractor reports, has resulted in flooding damage. Another potential tripping issue includes condensate pumps used for air-handling equipment in basements or the furnace itself if it has a variable speed ECM blower motor. The issue has been raised that all electronically commutated motors (ECMs) can be impacted by Class A GFCI devices in the same way as variable speed compressors. At this time, it is not determined if this is an installation practice issue or an issue that must be resolved in the codes and standards arena.
ACCA is Involved
ACCA continues to lead the way in working with allied associations to resolve the GFCI nuisance issues in codes and standards. We are coordinating with groups such as the National Association of Home Builders (NAHB), the Leading Builders of America (LBA), the AHRI, and others to achieve this goal. ACCA’s Codes Subcommittee also provides guidance in this effort. Our contractor members are in a precarious position in that any potential nuisance tripping issues in the field can adversely affect their reputation and business as well as create customer doubts about the equipment they are installing. We will continue to keep our members informed as developments dictate throughout the year.
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