Selective coordination is defined in NEC^® Article 100 as follows:

“Coordination, Selective (Selective Coordination). Localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the selection and installation of overcurrent protective devices and their ratings or settings for the full range of available overcurrents, from overload to the maximum available fault current, and for the full range of overcurrent protective device opening times associated with those overcurrents.” This definition makes it clear that there is no time delay allowed since the selective coordination is “for the full range of available overcurrents.”

In Oregon, the rules in 700.32 have been amended as follows:

700.32(A) General. Emergency system(s) overcurrent devices shall be selectively coordinated with all supply side overcurrent protective devices.

Selective coordination shall be selected by a licensed professional engineer or other qualified persons engaged primarily in the design, installation, or maintenance of electrical systems. The selection shall be documented and made available to those authorized to design, install, inspect, maintain, and operate the system.

For the purposes of this section, supply side overcurrent protection means those OCPDs on the emergency system supply side and not on the normal power supply side. The protection shall be selectively coordinated using the higher of the normal power supply fault current levels or emergency system fault current levels. OCPDs shall be selectively coordinated for .01 seconds and greater.

700.32(C) Modifications…

Exception No. 1: Selective coordination shall not be required between two overcurrent devices located in series if no loads are connected in parallel with the downstream device.

Exception No. 2: The requirements for selective coordination shall meet the coordination requirements in effect at the time of the original installation when the installation is being altered, maintained or repaired. The ground fault sensing function of overcurrent devices will only be required to selectively coordinate with the ground fault sensing functions of other protective devices.

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