In the 2020 NEC section 210.8(F) was added requiring that outlets providing power to residential split style air conditioners have GFCI protection. Unfortunately, this new section places a never-before tested requirement on residential HVAC equipment, which makes the possibility of nuisance tripping on new HVAC equipment highly likely. The highest efficiency HVAC equipment includes inverter or variable speed drive technology for these units to achieve the Department of Energy’s higher efficiency ratings.
All variable speed drives / inverters have some amount of leakage current at high frequencies, much higher than the 60hz leakage current that a GFCI seeks to protect against. This high frequency leakage current is not hazardous as it is understood that as the frequency increases the risk of shock decreases. GFCI breakers are sensitive to this high frequency leakage current and will trip even though there is no issue with the installation or the equipment.
Currently the UL standard that HVAC equipment is listed to (UL 1995) has no requirements for leakage current if the unit is hard wired, as most residential air conditioners/heat pumps are. In the future, HVAC equipment will be listed to UL 60335-2-40, which sets a limit of 10 milliamps of leakage current. However, this new standard is not mandatory until 1/1/2024. UL 943 is the standard to which GFCI breakers are listed and are required to trip at 5 milliamps of current. Even if HVAC equipment is listed to the UL 60335-2-40 standard, there is no guarantee it will be compatible with UL listed GFCI breakers This lack of coordination is what is leading to the nuisance tripping that customers are dealing with.
Because the authors of the 2020 NEC and UL have not communicated or coordinated with HVAC manufacturers; electricians and AHJs are forced to choose between a code compliant installation or one that allows the equipment to operate. HVAC manufacturers have made the NEC’s authors aware that some leakage current is unavoidable in variable speed units built in line with DoE’s requirements.
Because of this, many states that have adopted the 2020 NEC are choosing to delete/modify section 210.8(F) as they recognize that customers need their HVAC equipment to operate, especially as we go into the summer cooling season (including OR, MA, IA, UT and NC). This mismatch in code requirements has already resulted in nuisance trips of new residential HVAC equipment in several markets.
We urge each of you to contact your local state electrical board and bring this issue to their attention. Furthermore if your state is considering adopting the 2020 edition of the NEC, implore them to delete/modify section 210.8(F) as part of their adoption process so customers can have a functioning HVAC installation that is code compliant.
