Mike Dolt Enterprises
Mike Dolt Enterprises
User: DJK, Location: SAINT AUGUSTINE FLORIDA
Asked on: Thursday, January 30, 2025 at 2:05 pm EST
Answered on: Thursday, March 6, 2025 at 8:02 am EST
Question: 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??
You are interpreting the code correctly. The key phrase is "rated 150 volts or less to ground."Since you have a 240V open delta system with a 208V high leg, one of the phases (the high leg) has a voltage to ground of 208V. Therefore, the requirement for GFCI protection in 422.5(A)(7) does not apply to your dishwasher boost heater circuit.Your interpretation is valid. Here's a breakdown: NEC 422.5 focuses on voltage to ground
The code specifically limits the GFCI requirement to appliances rated "150 volts or less to ground."
Open Delta High Leg = >150V to Ground: With a 240V open delta system and a 208V high leg, one phase has 208V to ground. This exceeds the 150V threshold in the code.Because of this, it's not possible to install the required equipment. Flag for review