GFCI BREAKER ON A DELTA SYSTEM

[DJK]

Hello to all,


I currently have a situation on a small restaurant where the AHJ wants the 3 phase, 40 amp circuit feeding the boost heater for the dishwasher to be protected by a GFCI.

The issue in this case is the utility voltage present is 120/240 volt open delta with a 208 volt high leg.

Square D does not make a GFCI breaker rated to work for the available voltage. They only manufacture 3 pole GFCI breakers rated 120/208Y. I suspect the other breaker manufacturers are also in the same boat.

NEC 2020 article 422.5 states the following


"Appliances identified in 422.5(A)(1) through (A)(7) rated 150 volts or less to ground and 60 amperes or less, single- or 3-phase, shall be provided with Class A GFCI protection for personnel. Multiple Class A GFCI protective devices shall be permitted but shall not be required.
(7)Dishwashers”

The way I interpret the above code reference is sense we have a 120/240 volt 3 phase open delta system with a 208 volt high leg we are not required to GFCI protect it sense one of the phases is over 150 volts to ground.

Am I interpreting the code correctly? I understand that it is optimal to have class A GFCI protection, but I'm not sure it is possible in this case without the installation of a dry type transformer to change the delta voltage to wye voltage.

Thoughts??

 

[tortuga]

I would ask your AHJ in writing for permission to use a RCD (Residual Current Device) to provide ground fault protection of personnel. They are considered equivalent to a Class A GFCI in performance outcome, as they have been used out side the US for decades on stuff like swimming pools.
There are old threads on here from years back debating the differences RCD vs GFCI, but as of 2025 the IEC standard for ground fault protection of personnel (RCD) is literally accepted in every country other than the US, Canada and Mexico as best in class.

 

[don_resqcapt19]

I would ask your AHJ in writing for permission to use a RCD (Residual Current Device) to provide ground fault protection of personnel. They are considered equivalent to a Class A GFCI in performance outcome, as they have been used out side the US for decades on stuff like swimming pools.
There are old threads on here from years back debating the differences RCD vs GFCI, but as of 2025 the IEC standard for ground fault protection of personnel (RCD) is literally accepted in every country other than the US, Canada and Mexico as best in class.

The AHJ would have to give written special permission, and I highly doubt that the legal counsel for the agency that governs the AHJ would permit that. I know our legal counsel has directed that no special permissions be granted.

 

[jaggedben]

...


"Appliances identified in 422.5(A)(1) through (A)(7) rated 150 volts or less to ground and 60 amperes or less, single- or 3-phase, shall be provided with Class A GFCI protection for personnel. Multiple Class A GFCI protective devices shall be permitted but shall not be required.
(7)Dishwashers”

The way I interpret the above code reference is sense we have a 120/240 volt 3 phase open delta system with a 208 volt high leg we are not required to GFCI protect it sense one of the phases is over 150 volts to ground.

Am I interpreting the code correctly? ...

In my opinion you are interpeting the code correctly. The voltage to ground of one of the 'given conductors' (see definition of voltage to ground) feeding the appliance is above 150V so that can be applied to the appliance as a whole. The fact they don't make the breaker you want is corroborating evidence; if it were commonly understood to be required, more likely that breaker would exist.

 

[tortuga]

The AHJ would have to give written special permission

You only need special permission if the AHJ is changing what the code says (permitting an alternate method) not what listing standards they approve. (see 110.3)

 

[don_resqcapt19]

You only need special permission if the AHJ is changing what the code says (permitting an alternate method) not what listing standards they approve. (see 110.3)

True, but if the code is requiring GFCI and you are using a RCD, that is an alternate method requiring special permission.
While the RCD is accepted elsewhere, it is not under the NEC.
However if the ground fault protection is not required by the code, there would be no issue.

 

[electrofelon]

I would ask your AHJ in writing for permission to use a RCD (Residual Current Device) to provide ground fault protection of personnel.

Just curious, as I have never looked: are those readily available in the states?

 

[jaggedben]

Just a thought:

If you can find any GFCI device for a 240V high-leg delta, and put it in series on the supply side of the appliance, then you don't need the panel breaker to be GFCI. If you can't that seems like further evidence that this is not considered to be required.

 

[tortuga]

Just curious, as I have never looked: are those readily available in the states?

You can get them as a din rail mount and put it in its own enclosure.
The main OCPD stays in the panelboard.

 

[ramsy]

as of 2025 the IEC standard for ground fault protection of personnel (RCD) is literally accepted in every country other than the US, Canada and Mexico as best in class.

Half the states have been motivated enough to remove AFCI, and several sections of GFCI, bypassing NFPA thru legislative amendment.

code is requiring GFCI and you are using a RCD, that is an alternate method requiring special permission.

If amendment authorized 2025 IEC standard for ground fault protection of personnel (RCD) in place of xFCI, 120v RCD devices may happen, appliances may work again, and the NFPA may not matter.

 

[Jraef]

They are considered equivalent to a Class A GFCI in performance outcome, as they have been used out side the US for decades on stuff like swimming pools.
There are old threads on here from years back debating the differences RCD vs GFCI, but as of 2025 the IEC standard for ground fault protection of personnel (RCD) is literally accepted in every country other than the US, Canada and Mexico as best in class.

Not entirely true. Yes it is true that these devices are what is used in other parts of the world, but RCDs have a 30mA trip threshold (or higher), 6x higher than that of a Class A GFCI. They are not equivalent and the NEC does not recognize them as valid replacement. If UL listed as a Class B or higher device, they can be used for GFEP (Ground Fault Equipment Protection), but the term “Class A GFCI” is specific to what we use here.

 

[tortuga]

Yes it is true that these devices are what is used in other parts of the world,

Yeah thats whats interesting pretty much everywhere else besides Canada and Mexico, and they are made by all the major manufacturers

but RCDs have a 30mA trip threshold (or higher), 6x higher than that of a Class A GFCI. They are not equivalent

Thats a myth, I know of no evidence to support the claim that the ma makes a difference on a 240V boost heater (fixed equipment) with a equipment grounding conductor bonding all metal parts like we're discussing.
The miliamp difference your taking about is 0.024 amps. barely x4 higher than that of a GFCI.
Consider duration of exposure at the moment of contact with a live part, I will be hit by a full electric surge so that makes virtually no difference as the RCD trips in 10-30ms which is faster than a GFCI.

Dont take my word let me quote our pals at Eaton on page 4 of their RCD application guide:

It might appear that the higher the sensitivity the better. Highly sensitive RCD are very likely to frequent tripping due to
leaking currents and their contribution to safety is not high. Incase of a human being’s contact with a live part, current will pass
through the body, being only limited by the body’s impedance, and the residual current device will only react after certain time (10 -
- 30 milliseconds).
At the moment of contact with a live part, the person will be hit by a full electric surge and it makes virtually no
difference if a residual current device with a sensitivity of 10 or 30 mA is applied.

 

[jim dungar]

There is no personnel level GF protective device that prevents electric shock.

I know of no major manufacturer that has ever made an effort to introduce or promote their line of RCD in any market that requires Listed products. To my knowledge UL943 is the only standard that can be used for Listing GFCI.

I would check with my liability insurance underwriter/ legal advisor before suggesting unListed RCD products in lieu of Listed Class A devices.

 

[kwired]

There is no personnel level GF protective device that prevents electric shock.

I know of no major manufacturer that has ever made an effort to introduce or promote their line of RCD in any market that requires Listed products. To my knowledge UL943 is the only standard that can be used for Listing GFCI.

I would check with my liability insurance underwriter/ legal advisor before suggesting unListed RCD products in lieu of Listed Class A devices.

There likely is no listed class A device that is intended to use on high leg, corner grounded or even ungrounded delta, and NEC doesn't require it on those types of supplies per the section mentioned either.

Bottom line OP's inspector is wrong to require GFCI protection for this appliance.

NEC was wrong to require GFCI back when they first added dishwasher to the list of items requiring GFCI. The device manufacturers as well as the appliance manufacturers applauded them though. It was initially a fix to a problem that really needed other solutions, now it has just become a "because we can" reason to add more items to the list of things that need GFCI protection and I expect that list to grow in years to come with little justification in most of the additions.

 

[tortuga]

There is no personnel level GF protective device that prevents electric shock.

One of the leaders in RCD technology is Schnieder Electric (its the parent company of Square D).
They are a pioneer in RCD's, which unlike UL's proposals, is a product that exists and is readily available ( just not in the US listed market)
As you can see this old promo video on their RCD's they advertise RCD's prevent electric shocks:

Schnieder (Square D) has probably invested millions (perhaps tens of millions) on R&D and testing of RCD's and has a wealth of internal data on RCD's.
If they got a signal that a large US state would accept RCD's they could very easily leverage their vast experience with RCD's and hop thru the hoops needed to reach the US market as a Class-A device. They have been leaders and experts in harmonizing IEC &CSA & UL standards.

The problem is if AHJ's keep drinking the UL 6ma trip current kool-aid there wont be a market, which is why we should dispel the myth that a RCD and a GFCI provide different outcomes.
UL keeps blocking and ignoring existing technology, not because it does not work, as companies like Schnieder have proven it does provide the shock protection for personell as intended by the NEC.

 

[don_resqcapt19]

Yeah thats whats interesting pretty much everywhere else besides Canada and Mexico, and they are made by all the major manufacturers

Thats a myth, I know of no evidence to support the claim that the ma makes a difference on a 240V boost heater (fixed equipment) with a equipment grounding conductor bonding all metal parts like we're discussing.
The miliamp difference your taking about is 0.024 amps. barely x4 higher than that of a GFCI.
Consider duration of exposure at the moment of contact with a live part, I will be hit by a full electric surge so that makes virtually no difference as the RCD trips in 10-30ms which is faster than a GFCI.

Dont take my word let me quote our pals at Eaton on page 4 of their RCD application guide:

Probably the only time it would make a difference is where the current flow through the person is above 5mA and below 30 mA. That could result in the person not being able to let go of the energized conductor and that can be fatal after a minute or two. I expect that a path through a person that would limit the current to that level would be somewhat rare.

 

[don_resqcapt19]

One of the leaders in RCD technology is Schnieder Electric (its the parent company of Square D).
They are a pioneer in RCD's, which unlike UL's proposals, is a product that exists and is readily available ( just not in the US listed market)
As you can see this old promo video on their RCD's they advertise RCD's prevent electric shocks:

Schnieder (Square D) has probably invested millions (perhaps tens of millions) on R&D and testing of RCD's and has a wealth of internal data on RCD's.
If they got a signal that a large US state would accept RCD's they could very easily leverage their vast experience with RCD's and hop thru the hoops needed to reach the US market as a Class-A device. They have been leaders and experts in harmonizing IEC &CSA & UL standards.

The problem is if AHJ's keep drinking the UL 6ma trip current kool-aid there wont be a market, which why we should dispel the myth that a RCD and a GFCI provide different outcomes.
UL keeps blocking and ignoring existing technology, not because it does not work, as companies like Schnieder have proven it does provide the shock protection for personell as intended by the NEC.

Yet they have at least one member on the UL 943 technical panel and they have never presented a proposal for change in the UL 943 standard. ( at least not in the past 7 or 8 years) The same can be said for the other worldwide manufacturers that have members on that panel.

Remember the UL standards are much like the NEC...changed based on submitted proposals and those are acted on in a manner that is identical to that used for the NEC as the product standards and the NEC are both ANSI consensus documents covered by the same ANSI rules for the development of consensus standards.

 

[jim dungar]

As you can see this old promo video on their RCD's they advertise RCD's prevent electric shocks:

All of these devices allow some amount of current to flow before they react. Current flowing through the human body is an electrical shock.

If a major manufacturer thought it was worth it they would be pushing their products in North America.

 

[ramsy]

Remember the UL standards are much like the NEC...changed based on submitted proposals and those are acted on in a manner that is identical to that used for the NEC as the product standards and the NEC are both ANSI consensus documents covered by the same ANSI rules for the development of consensus standards.

UL, ANSI, & NEC 110.3(B) make end users responsible to push xFCI breaker reset buttons that fail while energized.

To my knowledge UL943 is the only standard that can be used for Listing GFCI.

Besides the end-user test, what standard checks Thermal-Magnetic function after push-button resets fail?

 

[don_resqcapt19]

UL, ANSI, & NEC 110.3(B) make end users responsible to push xFCI breaker reset buttons that fail while energized.

Besides the end-user test, what standard checks Thermal-Magnetic function after push-button resets fail?

The push button AFCI or GFCI test has nothing to do with the thermal magnetic function of the breaker. That function is mechanical, while the AFCI or GFCI have an electronic function that engages a solenoid to cause the breaker to open.