AC Units tripping GFI protection

[mwm1752]

It's a compressor motor - trips GFI breaker - Industry has not caught up - what now can be done besides "change the unit"

 

[mwm1752]

Crickets? No one has had this issue?

 

[don_resqcapt19]

There are issues with some AC equipment having VFDs and the new GFCI requirements. As you said, the code and the HVAC industry are out of sync. Texas just removed 210.8(F) from their code for this reason.

There is a pool pump manufacture that also has this issue, but has found that their equipment will work just fine with Siemens GFCI breakers, but sometimes trip when other brands are used. I have not read anything about someone trying this fix with AC equipment.

 

[Dennis Alwon]

I thought there is a TIA about this issue that extends the date to 2023 before gfci is required for ac units

 

[Dennis Alwon]

Here is the article about this issue

NFPA 70 - NFPA Journal, November/December 2020

Addressing issues around new GFCI requirements in the 2020 NEC

www.nfpa.org

Excerpt taken from the article

Because of this, the NEC is processing a Tentative Interim Amendment on 210.8(F) in order to delay the implementation for these mini-split systems until January 1, 2023. This TIA is currently in the public comment stage before it goes back to the committee for deliberation and action.

 

[gadfly56]

I thought there is a TIA about this issue that extends the date to 2023 before gfci is required for ac units

Dennis, I looked on line at the current and proposed TIA's for the 2020 and 2017 editions and didn't see anything about GFCI's for AC equipment.

 

[gadfly56]

Here is the article about this issue

NFPA 70 - NFPA Journal, November/December 2020

Addressing issues around new GFCI requirements in the 2020 NEC

www.nfpa.org

Excerpt taken from the article

Still nothing currently in the docket for 210.8(F) that I could find.

 

[Dennis Alwon]

Still nothing currently in the docket for 210.8(F) that I could find.

I couldn't find it either so I am not sure... That article may be incorrect

 

[Dennis Alwon]

There is a thread by Texie about this https://forums.mikeholt.com/threads/texas-and-gfcis-for-a-c.2561154/

Apparently Texas amended the requirement.

 

[Dennis Alwon]

When we finally get to accept the 2020-- October 2021 supposedly, we (NC) already have an amendment to delete 210.8(F) altogether. That is assuming it passes the building council

 

[don_resqcapt19]

There were two attempts to get a TIA for this issue, but they both failed ballot.

 

[Dennis Alwon]

Thanks Don, I thought I had read something about it. It's ridiculous to think that it is required even if the a/c won't work with it.... It is mostly the mini splits that are the issue...I am told

 

[don_resqcapt19]

Thanks Don, I thought I had read something about it. It's ridiculous to think that it is required even if the a/c won't work with it.... It is mostly the mini splits that are the issue...I am told

There are a number of issues with this. One is that listed equipment that is intended to be only hard wired, is not evaluated for use with GFCIs, and in addition, some of those product standards permit a leakage current over twice the level needed to trip a Class GFCI. The product standards assume that leakage current is not really an issue with hardwired equipment as the required EGC will take care of any shock or safety issues from the leakage current.

In addition, it appears that the VFDs used in some of this equipment do not play nicely with GFCIs.
Much the same as with the pool pumps where one manufacturer only recommends the use of Siemens' GFCI breakers for their pool pumps as other brands of GFCI breakers tend to nuisance trip.

I wonder if anyone has looked at this for the AC equipment?

 

[Dennis Alwon]

I thought I would share this with everyone. It was sent to Mike Holt in an email and if you subscribe to his messages you will see this. NC has already delete this section from the 2020 if it gets adopted which they expect it will.

Maybe someone would like to explain why their is normal leakage in speed drives-- inverters also are an issue

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.

 

[mbrooke]

Maybe someone would like to explain why their is normal leakage in speed drives-- inverters also are an issue

I think it boils down to the equation XC=1/(2πfC), where f = frequency. The high frequency output of the inverter increases leakage current to ground to the point 5ma is exceeded.

Personally I think a simple code table rule limiting the run length of any given wire size would be the most fair for everyone on all sides.

 

[romex jockey]

the '20 went pro-gfci far more than previous cycles, but for all the wrong reasons

~RJ~

 

[mwm1752]

I think it boils down to the equation XC=1/(2πfC), where f = frequency. The high frequency output of the inverter increases leakage current to ground to the point 5ma is exceeded.

Personally I think a simple code table rule limiting the run length of any given wire size would be the most fair for everyone on all sides.

impossible to inspect such a rule - Maybe we need to be more observant of wiring methods so equipment frames will not be energized(oh we do that now)

 

[mbrooke]

impossible to inspect such a rule - Maybe we need to be more observant of wiring methods so equipment frames will not be energized(oh we do that now)

IMO, CMP-5 is more concerned about potential inadequacies from 250.4 A 5 and 430.52. Their plan to gradually mandate GFCIs on all circuits.

However, IMO, where the the EGC is connected to the AC unit capable of clearing a short circuit quickly a GFCI should not be required on AC units.

 

[don_resqcapt19]

IMO, CMP-5 is more concerned about potential inadequacies from 250.4 A 5 and 430.52. Their plan to gradually mandate GFCIs on all circuits.

However, IMO, where the the EGC is connected to the AC unit capable of clearing a short circuit quickly a GFCI should not be required on AC units.

I don't believe that there is any GFCI rule in an article that is handled by CMP5. Most of the GFCI rules are in Article 210 which is under CMP2.

 

[mbrooke]

I don't believe that there is any GFCI rule in an article that is handled by CMP5. Most of the GFCI rules are in Article 210 which is under CMP2.

Right, however, IMO... CMP-5 is waving the flag...