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.