Section 16060 GROUNDING AND BONDING

Section 16060

GROUNDING AND BONDING

PART 1 - GENERAL

1.1 THE REQUIREMENT

A. The Contractor shall furnish all tools, equipment, materials, and supplies and shall perform all labor required to complete the work as indicated on the drawings and specified herein.

B. Electrical grounding and bonding systems shall be installed as indicated herein and/or on the other Contract Documents with materials including, but not limited to, cables/wires, connectors, solderless lug terminals, grounding electrodes and plate electrodes, bonding jumper braid, exothermic connections, and additional accessories needed for a complete installation. Where materials or components are not indicated, provide products which comply with NEC, UL, and IEEE requirements and with established industry standards.

C. System ground conductors shall run continuously in duct banks and cable trays, through manholes, handholes, and other raceways. The system ground conductor shall be connected to the structure grounding systems to provide a continuous ground system.

1.2 RELATED WORK SPECIFIED ELSEWHERE

A. The requirements following divisions and sections applies to the work of this Section.

1. Section 01660

2. Division 11

3. Division 15

4. Division 16

5. Division 17

B. Materials, equipment and devices furnished and installed under Contracts with raceway and electrical conductors furnished, installed, and connected under Division 16, Electrical.

1.3 REFERENCED SPECIFICATIONS, CODES AND STANDARDS

A. All work specified herein shall conform to or exceed the applicable requirements of the referenced portions of the following publications to the extent that the provisions thereof are not in conflict with other provisions of these specifications.

B. Comply with the current provisions of the following Codes and Standards.

1. Codes and Standards

NEC National Fire Protection Agency (NFPA) – 70 National

Electrical Code (NEC), latest adopted version

CCR Title 8, Industrial Relations, Subchapter 5, Electrical

Safety Orders, California Code of Regulations.

2. Commercial Standards

ANSI/IEEE 80 Guide for Safety in AC Substation Grounding

ANSI/UL 467 Safety Standard for Grounding and Bonding Equipment

IEEE 142 Grounding of Industrial and Commercial Power Systems

C. All equipment furnished by the Contractor shall be listed by and shall bear the label of Underwriters' Laboratories, Incorporated, (UL) or of an independent testing laboratory acceptable to OCSD.

D. The construction and installation of all electrical equipment and materials shall comply with all applicable provisions of the CAL OSHA Safety orders. (Title 8 CCR, as applicable), State Building Standards, and applicable local codes and regulations.

1.4 CONTRACTOR SUBMITTALS

A. Submittals shall be made in accordance with the requirements of Section 16010.

B. General Provisions: Submittals shall conform to the requirements of Section 16080, Section 16120 and additional requirements specified herein. Submittals shall be made for, but not be limited to the following:

1. Catalog literature for all products.

2. Certified copies of ground test results.

3. Field test procedures including lists of test equipment to be used.

1.5 QUALITY ASSURANCE

A. Quality assurance shall be in accordance with the requirements of Section 16010 and

Section 16080.

PART 2 - PRODUCTS

2.1 GROUND RODS

A. Provide copper ground rods not less than 3/4 inch in diameter, 10-feet long driven full length into the earth. Special requirements shall be as shown and as specified herein. In chemical areas stainless steel rods 3/4" shall be used.

2.2 GROUND CONDUCTORS

A. Provide grounding conductors of the size shown and the type specified in Section 16120.

In no case shall the size of any grounding conductor be less than that stipulated by the

NEC for that specific application.

B. All grounding conductors furnished shall be composed of material resistant to any existing corrosive conditions or shall be suitably protected against such conditions.

2.3 GROUND CONNECTIONS

A. For below grade connections, provide exothermic-welded connectors. B. For above grade connections, provide bolted connectors.

C. Embed all conduits in betonite, 6” all sides of conductor.

PART 3 - EXECUTION

3.1 GENERAL

A. The grounding electrode system shall consist of concrete encased, bare #2/0 AWG copper ground conductors and/or ground rods. Each duct bank shall contain a concrete encased, bare #2/0 AWG system ground conductor.

B. The UFER concrete-encased ground conductor shall be at least 20 feet in length and laid in a straight line located approximately two-inches above the bottom of the concrete pour.

C. Each metallic raceway, panel, switchboard, and other metallic devices associated with the electrical and instrumentation systems shall be bonded to this system. All equipment enclosures, devices, etc. shall be grounded.

D. Ground rods shall be driven or concrete encased bare copper conductors installed before a building or structure is built, and ground conductors shall be brought through the concrete to accessible points for grounding equipment via a schedule 40 PVC pipe sleeve. Each structure or building where switchgear, MCCs, switchboards, panelboards, etc. is installed shall have a ground system.

E. Driven ground rods stainless steel ¾-inch diameter by 10 feet in length.

F. All connections of ground cable to rods or to cable shall be by means of exothermic welded connections or compression connectors or bolted as indicated in Section 2.3.

G. The Contractor shall ground the electrical service system neutral at the service entrance equipment to the grounding electrode system and ground each separately derived system, including the UPS, neutral to the nearest effectively grounded structural steel member or the grounding electrode system.

H. The Contractor shall connect together service equipment enclosures, exposed noncurrent carrying metal parts of electrical equipment, metal raceway systems, grounding conductor in raceways and cables, receptacle ground connectors, and plumbing systems as required by Section 250-80 of the National Electrical Code.

I. Unless otherwise indicated on the Contract Documents, the Contractor shall provide electrical grounding conductors for grounding system connections that match power supply wiring materials and are sized according to NEC. All equipment grounding conductors shall consist of a separate insulated equipment grounding conductor run in the conduit or multiconductor cable from the equipment to the MCC, panelboard, switchgear, etc. equipment ground bus. A separate equipment grounding conductor, in addition to the cable shields, shall be provided in each raceway containing medium voltage power cables.

J. The Contractor shall terminate feeder and branch circuit insulated equipment-grounding conductors with grounding lug, or bushing.

K. The Contractor shall connect together metal raceway systems, cable tray systems, and grounding conductors in raceways and cables, as required by Section 250-80 of the National Electrical Code. The cable tray ground cable shall be sized for the largest circuit breaker serving the cable tray system.

L. The Contractor shall tighten grounding and bonding connectors and terminals, including screws and bolts, to the manufacturer's recommended torque values. Where manufacturer’s torque values do not exist, comply with torque values specified in UL

486A.

M. Except where specifically indicated otherwise, ground all exposed noncurrent-carrying metallic parts of electrical equipment, raceway systems, and the neutral of all wiring systems in strict accordance with the state, and other applicable laws and regulations.

N. Where grounding conductors are shown, bond the wires to metallic enclosures at each end and to all intermediate metallic enclosures. Connect grounding conductors to all grounding bushings on raceways. Where any equipment contains a ground bus, extend and connect grounding conductors to that bus. Connect the enclosure of the equipment containing the ground bus to that bus. Use insulated ground conductors when ground conductor is installed inside conduits enclosing the power conductors.

O. Ground connection to equipment and ground buses shall use ground lugs compatible with copper. Connections to enclosures not provided with ground buses or ground terminals shall be by clamp type lugs added under permanent assembly bolts or under new bolts drilled and added through enclosures other than explosion proof, or by grounding locknuts or bushings. Explosion proof enclosures not provided with any of the above grounding means shall be grounded by the addition of an adjacent junction box with a ground lug. Ground cable connections to anchor bolts, against gaskets, paint, or varnish, or on bolts holding removable access covers will not be permitted.

P. Install sufficient ground rods in addition to code required grounding so that resistance to ground as tested by standard methods does not exceed 1 ohm unless otherwise accepted. Where more than one rod is required, install rods at least 6-feet apart.

Q. Ground shields of any shielded power cable at each splice or termination in accordance with recommendations of the splice or termination manufacturer. Ground shields of any control cables in accordance with the details shown.

R. Ground metal sheathing and any exposed metal vertical structural elements of buildings.

Ground metal fences enclosing electrical equipment. Bond any metal equipment platforms which support electrical equipment to that equipment. Provide good electrical contact between metal frames and railings supporting pushbutton stations, receptacles, instrument cabinets, etc., and raceways carrying circuits to these devices.

S. Bond neutrals of transformers within buildings to the system ground network, or to any additional indicated grounding electrodes.

T. Ground cable penetrations through building exterior walls shall enter within 3 feet below finish grade and shall be prepared with a water stop. Unless otherwise indicated, the water stop shall include filling the space between the strands with solder and soldering a

12 inch copper disc over the cable.

U. Ground cable near the base of a structure shall be in earth and as far from the structure as the excavation permits but not closer than 6 inches.

V. The main grounding conductor when exposed within a building shall be copper bar supported with suitable spacers to one inch from the structure. Unless otherwise indicated on the drawings, the ground bus shall not be smaller than 1/4 by one inch rectangular.

W. Lighting fixtures and convenience outlets shall be grounded with a separate ground conductor.

X. The grounding system shall be bonded to station piping by connection to the first flange inside the building on either a suction or discharge pipe which will form a good ground connection. The connection shall be made with a copper bar or strap by drilling and tapping the flange and providing a bolted connection.

Y. Ground conductors on equipment shall be formed to the contour of the equipment and firmly supported. 250-92-C2 ex. #6 wire and larger shall be in a raceway to prevent physical damage.

Z. All ground connection hardware, bolts, and nuts shall be high strength, high conductivity copper alloy.

AA. Ground cables with encased underground conduit banks shall be as indicated on the drawings.

BB. Ground cables in underground circuits shall be bonded with main ground cables in each maintenance hole and handhold. Maintenance hole hardware and cover shall be effectively grounded.

CC. Liquid tight flexible conduits shall be provided with separate equipment grounding conductors sized in accordance with the NEC. The equipment grounding conductor shall be bonded to an approved grounding bushing and terminal lug. The grounding conductor can be installed outside the conduit if the required size is greater that No. 10.

DD. Exposed splices and connections for bare copper conductors and buses shall be protected by wrapping with heat shrink tape or covering.

3.2 GROUNDING CONNECTIONS

A. Unless shown otherwise, make connections of grounding conductors to ground rods at the upper end of the rod with the end of the rod and the connection point below finished grade.

B. Make connections of sections of outdoor ground mats (counterpoise) for substations or other equipment underground. Make connections of other grounding conductors generally accessible.

C. In manholes, install ground rods with ends 4 to 6-inches above the floor with connections of grounding conductors fully visible and accessible. Contractor shall bury at least 8 feet of rod.

D. When making exothermic welds, wire brush or file the point of contact to a bare metal surface. Use exothermic welding cartridges and molds in accordance with the manufacturer's recommendations. After welds have been made and cooled, brush slag from the weld area and thoroughly clean the joint.

E. Use connectors of proper size for conductors and ground rods specified. Use connector manufacturer's compression tool. Notify the Engineer and the Inspector prior to backfilling any ground connections.

3.3 FIELD TESTS

A. The grounding system shall be tested in accordance with Section16080.

END OF SECTION