In the NEC^®, Section 230.95 requires ground-fault protection (GFP) of equipment for solidly grounded wye electric services of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase for each service disconnect rated 1000 amperes or more. Similar requirements are found in 210.13 for branch circuit disconnects and in 215.10 for feeder disconnects.

The most common installation requiring GFP would be a 480 volt service disconnect of 1000 amps or larger on a solidly grounded wye electrical system.

When GFP is first installed, performance testing is required.

In Oregon, the OESC states the following:

OESC 230.95(C) Performance Testing. The ground-fault protection system shall be performance tested when first installed on site. This testing shall be conducted by a qualified person(s) having proper training and experience required to perform and evaluate the results of such performance testing, using a test process of primary current injection, in accordance with instructions that shall be provided with the equipment. A written record of this testing shall be made, signed by the person(s) performing this test, and shall be available to the authority having jurisdiction.

Oregon amendments to the 2023 NEC^® are located in “Table 1-E” of the Oregon Electrical Specialty Code (OESC) which can be seen using the following link or the OESC PDF file located near the bottom of the screen: 2023 OESC