Abstract: The Nuisance Current Blocker (NCB) is a unique protective device that utilizes resistors, gas discharge tube arrestors and choke/inductors to block low level current on equipment grounding conductors while maintaining an effective ground fault path to quickly activate overcurrent protective devices. EPRI reported that 60% of the electric grid's primary return current travels back through the earth. The NEC addresses this “Objectionable Current” in Section 250.6 and provides options to remediate in (B)(3) with “Interrupt the continuity of the conductor . . . ” or (B)(4) “Take other suitable remedial and approved action” and also in 250.6(E). Residential grounding systems have no protection against primary return current.