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Home My WebLink About26 05 26 GroundingBEARDSLEY DESIGN ASSOCIATES CORNELL – NCP GROUNDING STANDARD SPECIFICATIONS 26 05 26 – PAGE 1 of 5 MARCH 29, 2013 SECTION 260526 - GROUNDING PART 1 GENERAL 1.1 RELATED DOCUMENTS A. The Contract Drawings and the General Provisions of the Contract, including the General Conditions of the Contract for Construction, Supplementary Conditions, Special Conditions and Division 1 Specification Sections apply to the work of this Section. B. The Work of Section 26 01 01 - Electrical Basic Materials and Methods applies to the Work of this Section. 1.2 WORK INCLUDED: A. Provide a complete, operating, tested, functioning, documented grounding system including all work shown, specified, or required for proper system operation. B. All grounding and grounding circuitry shall equal or exceed the requirements of NEC, latest issue, Article 250. C. The raceway system which includes all metal conduit, wireways, pullboxes, junction boxes, bus ducts, built-up enclosures, enclosures, motor frames, etc., shall be made to form a continuous, conducting permanent ground circuit of the lowest practical impedance to enhance the safe conduction of ground fault currents and to prevent objectionable differences in voltage between metal non-load current carrying parts of the electrical system. D. In addition to the raceway system ground, an additional green wire ground shall be run in each raceway, sized for the largest circuit in the raceway. E. Telecommunications ground system consists of telecommunications ground bar (TGB) in all ITR’s and MTR’s. Refer to drawing for TGB type and location. Minimum #6 grounding riser between each ITR and MTR per riser diagram on drawings. Bonding in each ITR and MTR shall be from the TGB in each room to the following: network equipment racks and cabinets, cable runways, cable trays, metallic cable sheaths and raised floor system (if existing). 1.3 SUBMITTALS: A. Provide product data for each type of ground bar and associated ground lugs, at a minimum. BEARDSLEY DESIGN ASSOCIATES CORNELL – NCP GROUNDING STANDARD SPECIFICATIONS 26 05 26 – PAGE 2 of 5 MARCH 29, 2013 1.4 DEFINITIONS: A. Earth: interpreted as absolute ground, a theoretical location of zero electrical potential. B. Ground: interpreted as a made conducting connection to earth by employing such devices as a driven metal rod, a buried metal plate, a metallic water pipe, etc., or any multiple or combination of these devices, and the conductors which may interconnect any of the foregoing. C. System ground: interpreted as a low impedance made conducting ground plane or system, with a conducting connection to ground, established for the benefit of a particular electrical system or related systems. PART 2 PRODUCTS 2.1 CONDUCTORS: A. All exposed grounding conductors such as bars, straps, cables, flexible jumpers, braids, shunts, etc., shall be bare copper unless specifically noted or approved otherwise. B. Cable size shall be as required by NEC Code, Section 250, stranded, soft drawn or soft annealed, unless otherwise shown on plans or specified. C. Cable insulation type and color shall be as shown or as specified. D. Manufacturer to be same as specified in Section 260101 - Basic Materials and Methods. 2.2 CONNECTORS, CLAMPS, TERMINALS: A. Mechanical connectors and clamps shall be silicon bronze. B. Solderless compression terminals shall be copper, long-barrel, two-bolt. C. Make: Anderson, Burndy, Penn-Union, T&B, approved for use intended. 2.3 SOLDER: A. Solder prohibited for connections, except for high voltage cable metallic tape shields. 2.4 MOLDED FUSION WELDS: A. Process shall be "Cadweld," "Metalweld," "Thermoweld." BEARDSLEY DESIGN ASSOCIATES CORNELL – NCP GROUNDING STANDARD SPECIFICATIONS 26 05 26 – PAGE 3 of 5 MARCH 29, 2013 2.5 HARDWARE: A. All hardware shall be silicon bronze alloy. B. Make: "Durium," "Everdur." PART 3 EXECUTION 3.1 INSTALLATION, GENERAL: A. Bare copper bars, cables, fittings, etc., shall not be installed in cinder fill nor shall be covered with soil containing cinders or other corrosive material. B. Cables shall be installed with enough slack to prevent breaking stresses. C. All grounding conductors subject to mechanical damage shall be protected by rigid steel conduit or other suitable steel guards and in all cases where so protected shall be permanently and effectively grounded to said enclosure at each end of its length. D. Where grounding conductors pass through floor slabs, walls, etc., and are not encased in metal conduit, they shall be sleeved in fiber, or approved non-metallic conduit. E. All equipment ground bus, ground pads, frames, enclosures, etc., shall have surfaces at point of connection thoroughly cleaned and brightened just prior to actually making the connection. Touch-up damaged painted surfaces. F. Splices in wire or cable grounding conductors are prohibited. 3.2 INSTALLATION, RACEWAY SYSTEMS: A. All metal supports, cable trays, messenger cables, frames, brackets, races, etc., for any part of the raceway system, panels, switches, boxes, starters, controls, etc., which are not rigidly secured to and in contact with the raceway system, or which are subject to vibration and loosening, shall be bonded to the raceway system, the size of the bonding conductor in accordance with NEC Table 250-94. B. Termination of rigid conduit at all boxes, cabinets, and enclosures shall be made up tightly with a double locknut arrangement and a bushing, bushings being of the insulated type where required by NEC. C. Conduit which runs to or from all boxes, cabinets, or enclosures having BEARDSLEY DESIGN ASSOCIATES CORNELL – NCP GROUNDING STANDARD SPECIFICATIONS 26 05 26 – PAGE 4 of 5 MARCH 29, 2013 concentric or eccentric knockouts which partially perforate the metal around the conduit and hence impair the continuity of system ground circuits shall be provided with bonding jumpers sized in accordance with NEC Table 250-95 connected between a grounding type bushing/locknut on the conduit and a ground bus or stud inside the box, cabinet, or enclosure and attached thereto. D. Conduit expansion joints and telescoping sections of metal raceways shall be provided with bonding jumpers sized in accordance with NEC Table 250-95. E. Where flexible metallic conduit or liquid tight conduit is used, a bonding jumper shall be provided, sized in accordance with NEC Table 250-95. F. All non-metallic runs of conduit or raceway shall be provided with a system ground conductor sized according to Table 250-95. G. Where conduit enters or leaves any electrical enclosure with removable coverplates, provide conduit grounding bushings and bonding jumpers sized in accordance with NEC Table 250-95 between the grounding bushings and the enclosure rigid frame or ground bus. H. The ground conductors contained in the interstices of interlocked armor cable shall be connected to ground at every splice and termination point. 3.3 INSTALLATION, ATTACHMENT TO STRUCTURAL STEEL: A. Location of attachment bonds of ground conductors shall be at points not subject to mechanical damage, but if possible where accessible for inspection. B. Attach preferably by molded fusion welding process. C. Where welding is prohibited, attach by bolting, 7/16 inch hole in steel, 3/8 inch silicon bronze bolt, bolt end peened, steel surface bright and flat prior to bolting, just prior to bolting contact surfaces lightly coated with Vaseline or "NO-OX-ID-A Special." 3.4 INSTALLATION, SECONDARY ELECTRICAL SYSTEMS: A. The neutral conductor of each and every low voltage, single or polyphase, system or distribution system, except special isolated double insulated systems, shall be solidly connected at one point only; at the main secondary switchgear; to system ground and shall be sized for current carrying capacity, not to be less than the following, which are listed in preferential order: a. As shown or specified. b. As required by NEC, latest issue, Table 250-95. BEARDSLEY DESIGN ASSOCIATES CORNELL – NCP GROUNDING STANDARD SPECIFICATIONS 26 05 26 – PAGE 5 of 5 MARCH 29, 2013 c. Not less than 25 percent of the transformer full load current or main protective device rating, whichever is greater, based on NEMA standard bus size. B. Provide equipment grounding conductor, green colored insulation, with phase conductors, to primary side of all transformers rated 600 volts or less circuited to case and secondary neutral bushing, to motors, to motor control equipment, and to all convenience outlets, insulation shall be same type as phase conductors. C. Transformer secondary neutral bushings shall also to be circuited to nearest metallic water pipe, building steel, or ground rod. END OF SECTION 26 05 26