Current through Register Vol. 54, No.43, October 26, 2024
Section 208.600 - Sensitive ground faultAll three-phase electrically operated equipment operated on a working section inby the last open crosscut must receive power from a circuit equipped with a sensitive ground fault protection as specified in this section.
(1)Sensitive ground fault.(i) A sensitive ground fault protective device must be connected so that the associated circuit will be instantaneously interrupted upon the occurrence of a ground fault which may not exceed 300 milli-amperes nominally.(ii) A sensitive ground fault protective device on these circuits on equipment utilizing variable speed drives must be connected so that the associated circuit will be instantaneously interrupted upon the occurrence of a ground fault which may not exceed 300 milli-amperes nominally. If nuisance tripping occurs on these circuits, the devices shall be permitted to be adjusted to the minimum setting necessary to prevent nuisance tripping. In no case shall a device be adjusted greater than the lower value of 500 milli-amperes or 1/2 of the neutral ground resistor's current rating.(iii) The secondary main circuit breaker protecting any sensitive ground fault circuit subject to this section must also provide backup sensitive ground fault protection. Relay settings may include a short time delay (250mS) or a higher current setting, or both, to provide coordination. In no case shall a device be adjusted greater than the lower value of 500 milli-amperes or 1/2 of the neutral ground resistor's current rating.(2)Implementation schedule. This section is effective January 13, 2018, for load centers that power equipment that operates inby the last open crosscut and that are purchased after January 13, 2018, and load centers that are rebuilt at new mines after January 13, 2018. For load centers that power equipment that operates inby the last open crosscut that are located in or at a mine on January 13, 2018, sensitive ground fault protection shall be installed by January 13, 2023.The provisions of this §208.600 adopted January 12, 2018, effective 1/13/2018, 48 Pa.B. 251.The provisions of this §208.600 issued under sections 106 and 106.1 of the Bituminous Coal Mine Safety Act (52 P.S. §§ 690-106 and 690-106.1).