VA 26 05 26-2010 GROUNDING AND BONDING FOR ELECTRICAL SYSTEMS.pdf

1、09-10 26 05 26 - 1 SECTION 26 05 26 GROUNDING AND BONDING FOR ELECTRICAL SYSTEMS SPEC WRITER NOTE: Delete / _ / if not applicable to project. Also delete any other item or paragraph not applicable in the section and renumber the paragraphs. Insert additional provisions as required for this project.

2、PART 1 - GENERAL 1.1 DESCRIPTION A. This section specifies the general grounding and bonding requirements for electrical equipment and operations to provide a low impedance path for possible ground fault currents. B. “Grounding electrode system” refers to all electrodes required by NEC, as well as m

3、ade, supplementary, and lightning protection system grounding electrodes. C. The terms “connect” and “bond” are used interchangeably in this specification and have the same meaning. 1.2 RELATED WORK A. Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS: General electrical requirements and i

4、tems that are common to more than one section of Division 26. B. Section 26 05 21, LOW-VOLTAGE ELECTRICAL POWER CONDUCTORS AND CABLES (600 VOLTS AND BELOW): Low Voltage power and lighting wiring. C. Section 26 13 00, MEDIUM-VOLTAGE SWITCHGEAR: Medium voltage distribution switchgear. D. Section 26 13

5、 13, GENERATOR PARALLELING CONTROLS: Generator paralleling controls. E. Section 26 18 41, MEDIUM-VOLTAGE SWITCHES: Medium voltage switches. F. Section 26 22 00, LOW-VOLTAGE TRANSFORMERS: Low voltage transformers. G. Section 26 23 00, LOW-VOLTAGE SWITCHGEAR: Low voltage switchgear. H. Section 26 24 1

6、1, DISTRIBUTION SWITCHBOARDS: Low voltage distribution switchboards. I. Section 26 24 16, PANELBOARDS: Low voltage panelboards. J. Section 26 24 19, MOTOR CONTROL CENTERS: Low voltage motor control centers. K. Section 26 24 21, MOTOR CONTROL PANELBOARDS: Low voltage motor control panelboards. L. Sec

7、tion 26 32 13, ENGINE-GENERATORS: Engine-generators. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 26 - 2 M. Section 26 36 23, AUTOMATIC TRANSFER SWITCHES: Automatic transfer switches. N. Section 26 41 00, FACILITY LIGHTNING PROTECTION:

8、 Requirements for lightning protection. 1.3 QUALITY ASSURANCE Refer to Paragraph, QUALIFICATIONS, in Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS. 1.4 SUBMITTALS A. Submit in accordance with Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS. B. Shop Drawings: 1. Clearly pres

9、ent enough information to determine compliance with drawings and specifications. 2. Include the location of system grounding electrode connections and the routing of aboveground and underground grounding electrode conductors. C. Test Reports: Provide certified test reports of ground resistance. D. C

10、ertifications: Two weeks prior to final inspection, submit four copies of the following to the /Resident Engineer/ /COTR/: 1. Certification that the materials and installation are in accordance with the drawings and specifications. 2. Certification by the contractor that the complete installation ha

11、s been properly installed and tested. 1.5 APPLICABLE PUBLICATIONS Publications listed below (including amendments, addenda, revisions, supplements, and errata) form a part of this specification to the extent referenced. Publications are referenced in the text by designation only. A. American Society

12、 for Testing and Materials (ASTM): B1-07 Standard Specification for Hard-Drawn Copper Wire B3-07 Standard Specification for Soft or Annealed Copper Wire B8-04 Standard Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft B. Institute of Electrical and Electronics E

13、ngineers, Inc. (IEEE): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 26 - 3 81-1983 IEEE Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System C2-07 National Electrical Safety Code C. N

14、ational Fire Protection Association (NFPA): 70-08 National Electrical Code (NEC) 99-2005 Health Care Facilities D. Underwriters Laboratories, Inc. (UL): 44-05 . Thermoset-Insulated Wires and Cables 83-08 . Thermoplastic-Insulated Wires and Cables 467-07 Grounding and Bonding Equipment 486A-486B-03 W

15、ire Connectors PART 2 - PRODUCTS 2.1 GROUNDING AND BONDING CONDUCTORS A. Equipment grounding conductors shall be UL 44 or UL 83 insulated stranded copper, except that sizes No. 10 AWG 6 mm and smaller shall be solid copper. Insulation color shall be continuous green for all equipment grounding condu

16、ctors, except that wire sizes No. 4 AWG 25 mm and larger shall be identified per NEC. B. Bonding conductors shall be ASTM B8 bare stranded copper, except that sizes No. 10 AWG 6 mm and smaller shall be ASTM B1 solid bare copper wire. C. Conductor sizes shall not be less than shown on the drawings, o

17、r not less than required by the NEC, whichever is greater. SPEC WRITER NOTE: Remove the paragraph below if not required for the project. /D. Isolated Power System: Type XHHW-2 insulation with a dielectric constant of 3.5 or less./ 2.2 GROUND RODS A. Steel or copper clad steel, 0.75 in 19 mm diameter

18、 by 10 ft 30 M long, conforming to UL 467. B. Quantity of rods shall be as required to obtain the specified ground resistance, as shown on the drawings. 2.3 CONCRETE ENCASED ELECTRODE Concrete encased electrode shall be No. 4 AWG bare copper wire, installed per NEC. Provided by IHSNot for ResaleNo r

19、eproduction or networking permitted without license from IHS-,-,-09-10 26 05 26 - 4 2.4 MEDIUM VOLTAGE SPLICES AND TERMINATIONS Components shall meet or exceed UL 467 and be clearly marked with the manufacturer, catalog number, and permitted conductor size(s). 2.5 GROUND CONNECTIONS A. Below Grade:

20、Exothermic-welded type connectors. B. Above Grade: 1. Bonding Jumpers: Compression-type connectors, using zinc-plated fasteners and external tooth lockwashers. 2. Connection to Building Steel: Exothermic-welded type connectors. 3. Ground Busbars: Two-hole compression type lugs, using tin-plated copp

21、er or copper alloy bolts and nuts. 4. Rack and Cabinet Ground Bars: One-hole compression-type lugs, using zinc-plated or copper alloy fasteners. 2.6 EQUIPMENT RACK AND CABINET GROUND BARS Provide solid copper ground bars designed for mounting on the framework of open or cabinet-enclosed equipment ra

22、cks with minimum dimensions of 0.375 in 4 mm thick x 0.75 in 19 mm wide. 2.7 GROUND TERMINAL BLOCKS At any equipment mounting location (e.g., backboards and hinged cover enclosures) where rack-type ground bars cannot be mounted, provide screw lug-type terminal blocks. SPEC WRITER NOTE: Include Stand

23、ard Detail on drawings. Edit detail to suit project requirements. 2.8 GROUNDING BUS Pre-drilled rectangular copper bar with stand-off insulators, minimum 0.25 in 6.3 mm thick x 4 in 100 mm high in cross-section, length as shown on drawings, with 0.281 in 7.1 mm holes spaced 1.125 in 28 mm apart. PAR

24、T 3 - EXECUTION 3.1 GENERAL A. Ground in accordance with the NEC, as shown on drawings, and as specified herein. B. System Grounding: 1. Secondary service neutrals: Ground at the supply side of the secondary disconnecting means and at the related transformers. 2. Separately derived systems (transfor

25、mers downstream from the service entrance): Ground the secondary neutral. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 26 - 5 SPEC WRITER NOTE: Remove the paragraph below if not required for the project. /3. Isolation transformers and

26、isolated power systems shall not be system grounded./ C. Equipment Grounding: Metallic structures, including ductwork and building steel, enclosures, raceways, junction boxes, outlet boxes, cabinets, machine frames, and other conductive items in close proximity with electrical circuits, shall be bon

27、ded and grounded. SPEC WRITER NOTE: If appropriate for project, include details involving grounding for patient equipment and areas on plans. D. Special Grounding: For patient care area electrical power system grounding, conform to NFPA 99 and NEC. 3.2 INACCESSIBLE GROUNDING CONNECTIONS Make groundi

28、ng connections, which are normally buried or otherwise inaccessible (except connections for which access for periodic testing is required), by exothermic weld. 3.3 MEDIUM VOLTAGE EQUIPMENT AND CIRCUITS A. Switchgear: Provide a bare grounding electrode conductor from the switchgear ground bus to the

29、grounding electrode system. SPEC WRITER NOTE: Include duct bank and manhole grounding Standard Detail(s) on plans. B. Duct Banks and Manholes: Provide an insulated equipment grounding conductor in each duct containing medium voltage conductors, sized per NEC except that minimum size shall be 2 AWG 2

30、5 mm. Bond the equipment grounding conductors to the switchgear ground bus, to all manhole hardware and ground rods, to the cable shielding grounding provisions of medium-voltage cable splices and terminations, and to equipment enclosures. C. Pad-Mounted Transformers: 1. Provide a driven ground rod

31、and bond with a grounding electrode conductor to the transformer grounding pad. 2. Ground the secondary neutral. D. Lightning Arresters: Connect lightning arresters to the equipment ground bus or ground rods as applicable. Provided by IHSNot for ResaleNo reproduction or networking permitted without

32、license from IHS-,-,-09-10 26 05 26 - 6 3.4 SECONDARY VOLTAGE EQUIPMENT AND CIRCUITS A. Main Bonding Jumper: Bond the secondary service neutral to the ground bus in the service equipment. B. Metallic Piping, Building Steel, and Supplemental Electrode(s): 1. Provide a grounding electrode conductor si

33、zed per NEC between the service equipment ground bus and all metallic water pipe systems, building steel, and supplemental or made electrodes. Provide jumper insulating joints in the metallic piping. All connections to electrodes shall be made with fittings that conform to UL 467. 2. Provide a suppl

34、emental ground electrode and bond to the grounding electrode system. C. Service Disconnect (Separate Individual Enclosure): Provide a ground bar bolted to the enclosure with lugs for connecting the various grounding conductors. D. Switchgear, Switchboards, Unit Substations, Panelboards, Motor Contro

35、l Centers and Panelboards, Engine-Generators, and Automatic Transfer Switches: 1. Connect the various feeder equipment grounding conductors to the ground bus in the enclosure with suitable pressure connectors. 2. For service entrance equipment, connect the grounding electrode conductor to the ground

36、 bus. 3. Provide ground bars, bolted to the housing, with sufficient lugs to terminate the equipment grounding conductors. 4. Connect metallic conduits that terminate without mechanical connection to the housing, by grounding bushings and grounding conductor to the equipment ground bus. E. Transform

37、ers: 1. Exterior: Exterior transformers supplying interior service equipment shall have the neutral grounded at the transformer secondary. Provide a grounding electrode at the transformer. 2. Separately derived systems (transformers downstream from service equipment): Ground the secondary neutral at

38、 the transformer. Provide a grounding electrode conductor from the transformer to / the nearest component of the grounding electrode system / / the ground bar at the service equipment /. 3.5 RACEWAY A. Conduit Systems: Provided by IHSNot for ResaleNo reproduction or networking permitted without lice

39、nse from IHS-,-,-09-10 26 05 26 - 7 1. Ground all metallic conduit systems. All metallic conduit systems shall contain an equipment grounding conductor. 2. Non-metallic conduit systems, except non-metallic feeder conduits that carry a grounded conductor from exterior transformers to interior or buil

40、ding-mounted service entrance equipment, shall contain an equipment grounding conductor. 3. Conduit that only contains a grounding conductor, and is provided for its mechanical protection, shall be bonded to that conductor at the entrance and exit from the conduit. 4. Metallic conduits which termina

41、te without mechanical connection to an electrical equipment housing by means of locknut and bushings or adapters, shall be provided with grounding bushings. Connect bushings with a bare grounding conductor to the equipment ground bus. B. Feeders and Branch Circuits: Install equipment grounding condu

42、ctors with all feeders and power and lighting branch circuits. C. Boxes, Cabinets, Enclosures, and Panelboards: 1. Bond the equipment grounding conductor to each pullbox, junction box, outlet box, device box, cabinets, and other enclosures through which the conductor passes (except for special groun

43、ding systems for intensive care units and other critical units shown). 2. Provide lugs in each box and enclosure for equipment grounding conductor termination. D. Wireway Systems: 1. Bond the metallic structures of wireway to provide 100% electrical continuity throughout the wireway system, by conne

44、cting a No. 6 AWG 16 mm bonding jumper at all intermediate metallic enclosures and across all section junctions. 2. Install insulated No. 6 AWG 16 mm bonding jumpers between the wireway system, bonded as required above, and the closest building ground at each end and approximately every 50 ft 16 M.

45、3. Use insulated No. 6 AWG 16 mm bonding jumpers to ground or bond metallic wireway at each end for all intermediate metallic enclosures and across all section junctions. 4. Use insulated No. 6 AWG 16 mm bonding jumpers to ground cable tray to column-mounted building ground plates (pads) at each end

46、 and approximately every 49 ft 15 M. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 26 - 8 E. Receptacles shall not be grounded through their mounting screws. Ground receptacles with a jumper from the receptacle green ground terminal to

47、the device box ground screw and a jumper to the branch circuit equipment grounding conductor. F. Ground lighting fixtures to the equipment grounding conductor of the wiring system when the green ground is provided; otherwise, ground the fixtures through the conduit systems. Fixtures connected with f

48、lexible conduit shall have a green ground wire included with the power wires from the fixture through the flexible conduit to the first outlet box. G. Fixed electrical appliances and equipment shall be provided with a ground lug for termination of the equipment grounding conductor. H. Raised Floors:

49、 Provide bonding of all raised floor components. /See details on the drawings. / I. Panelboard Bonding in Patient Care Areas: The equipment grounding terminal buses of the normal and essential branch circuit panel boards serving the same individual patient vicinity shall be bonded together with an insulated continuous copper c