Low Resistance Grounding Specifications
This specification covers the technical requirements of low resistance neutral grounding resistors.
2.0 CONFORMANCE TO NATIONAL STANDARDS
The neutral grounding resistors shall be designed and factory-tested to IEEE Standard 32. The neutral grounding resistors shall be designed to conform to Seismic, Zone 2 requirements of the Uniform Building Code unless otherwise specified.
3.0 SERVICE CONDITIONS
Neutral grounding resistors shall be suitable for outdoor service and will be mounted on permanent structures.
The neutral grounding resistors shall have the ratings indicated in the chart below. (These ratings will be specified by the customer).
5.0 DESIGN DETAILS
The neutral grounding resistor shall be provided with an outdoor safety enclosure. The enclosure will have a solid top, screened bottom, side covers, and top mounted eye-bolts for handling ease. The enclosure finish will be mill galvanized or ANSI 61 gray unless otherwise specified. The enclosure will have 4-inch legs unless otherwise specified. The resistor will consist of stainless steel stamped grid elements for higher currents or edge wound resistors for lower currents, double insulated. The resistor terminals must be stainless steel. All resistor end frames, hardware, and non-current carrying spacers must be zinc plated steel at a minimum. If more than one resistor frame is required, series connections must be solid copper bus for grid resistors and Teflon coated wire for edge wound resistors. The resistor bank or banks will be mounted on porcelain standoff insulators with a rating equal to or greater than the line to neutral voltage. Neutral grounding resistors must be delivered to the jobsite completely assembled and ready for installation.
Neutral grounding resistors shall be provided with a nameplate which shall be fixed to the exterior of the enclosure. Furthermore, each resistor bank must be identified with a nameplate on each resistor bank end frame.
7.0 DATA, DRAWINGS, TEST REPORTS AND MANUALS
The supplier shall submit approval drawings within 5 working days after notification of contract award.
7.2 TEST REPORTS
Supplier shall submit certified test reports in accordance with IEEE Standard 32-1972.
Supplier shall submit complete Instruction and Maintenance manuals at the time of shipment. The manuals shall give complete and detailed instructions for unpacking, installation, inspection, connection, and maintenance.