Grounding and Bonding For Electrical SystemsME- Building Group

SECTION 260526–GROUNDING AND BONDING FOR ELECTRICAL SYSTEMS

PART 1 - GENERAL

1.1RELATED DOCUMENTS

  1. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division01 Specification Sections, apply to this SectionProvide all items, articles, materials, operations or methods listed, mentioned or scheduled on drawings and/or herein, including all labor and materials necessary and required for their completion.to complete the project

1.2SUMMARY

  1. This Section includes the basic requirements for grounding of electrical systems and equipment.
  2. Other Sections may supplement or replace requirements specified in this Section. Description of Systems
  3. Provide grounding system as indicated or specified.
  4. Grounding Conductors:
  1. Use bare for General Use Above and Below Grade
  2. Use bare In Ducts / Duct Banks
  3. Use green insulated in Conduit with Phase Conductors
  4. Insulated for Isolated Grounding Systems
  5. Grounding Connections:
  1. Use exothermic weld In Earth or Inaccessible Locations.
  1. Use exothermic weld to Structural Steel Used for Main Building Framing.
  2. To NonPermanently Fixed Equipment. Lugs bolted to the equipment.
  1. Related Work Specified In Other Sections:
  2. Division 16 Section “Electrical Acceptance Testing”.
  3. Division 16 Section “Wire and Cable (600V and Below)”.
  4. Division 3 Section “Concrete Work”.

1.3QUALITY ASSURANCE

  1. Comply with NFPA70.
  2. At a minimum, provide grounding per Article250.
  3. Comply with Contract Documents where specific types, larger sizes, or additional conductors as indicated exceed the minimum requirements.
  4. Comply with UL467.
  5. Listing and Labeling: Provide products specified in this Section that are listed and labeled.
  6. The Terms "Listed" and "Labeled": As defined in the National Electrical Code, Article 100.

PART 2 - PRODUCTS

2.1MANUFACTURERS

  1. Manufacturers: Unless otherwise directed by the Owner, provide products by one of the following:
  2. Chance: A. B. Chance Co.
  3. Erico Inc.; Electrical Products Group.
  4. Kearney.
  5. O-Z/Gedney Co.
  6. Thomas & Betts, Electrical.

2.2GROUNDING AND BONDING PRODUCTS

  1. Governing Requirements: Where types, sizes, ratings, and quantities indicated are in excess of National Electrical Code (NEC) requirements, the more stringent requirements and the greater size, rating, and quantity indications govern.

2.3WIRE AND CABLE GROUNDING CONDUCTORS

  1. Comply with Division26 Section "Low-Voltage Electrical Power Conductors And Cables." Conform to NEC Table8, except as otherwise indicated, for conductor properties, including stranding.
  2. Material: Use only copper wire for both insulated and bare grounding conductors.
  3. Equipment Grounding Conductors: Insulated with green color insulation.
  4. Grounding-Electrode Conductors: Stranded cable.
  5. Underground Conductors: Bare, tinned, stranded, except as otherwise indicated.
  6. Bare Copper Conductors: Conform to the following:
  7. Solid Conductors: ASTMB3.
  8. Assembly of Stranded Conductors: ASTMB8.
  9. Tinned Conductors: ASTMB33.

2.4CONNECTOR PRODUCTS

  1. Pressure Connectors: High-conductivity-plated units.
  2. Bolted Clamps: Heavy-duty type.

B.Exothermic-Welded Connections: Provided in kit form and selected per manufacturer's written instructions for specific types, sizes, and combinations of conductors and connected items.

C. Copper Compression Grounding:

  1. Anderson
  2. Burndy
  3. Panduit
  4. Penn Union
  5. Thomas & Betts

D.Grounding Fittings for Connecting to Water Pipe:

  1. Burndy GD or GG
  2. Thomas & Betts Series 2818 to 3821, 3824 and 3890
  3. Anderson Type GC

E.Grounding Fittings for Bonding a Ground Conductor to Its Own Conduit:

  1. Appleton Type GIB
  2. Burndy NE
  3. Penn Union BD
  4. O-Z Type GB
  5. Thomas & Betts Type TIG or 3800 Series

F.Grounding Fittings for Connection of Grounding Conductor to Fencing:

  1. Burndy GL or GD
  2. Penn Union GU or GH
  3. Anderson GC-110 or GC-143

2.5GROUNDING ELECTRODES

  1. Ground Rods: Copper-clad steel; 3/4 inches diameter, a minimum of10 feet long.

PART 3 - EXECUTION

G.Equipment Grounding Conductors: Comply with NEC Article250 for types, sizes, and quantities of equipment grounding conductors, except where specific types, larger sizes, or more conductors than required by NEC are indicated.

  1. Install equipment grounding conductor with circuit conductors for the items below in addition to those required by Code:
  2. All branch circuits, feeders and branch feeders
  3. Indoor Switchgear and Substations comply with the following:
  4. Install a suitable ground for each indoor switchgear and substation room. From a mat covering the entire area beneath the switchgear or substation room. Construct this mat of a continuous stranded bare copper cable connected to driven ground rods. Size ground conductors for the magnitude of the maximum available fault current, but not less than No. 4/0 AWG.
  5. Ground indoor switchgear and substations, all equipment structures, potheads, cable sheaths, cable trays, feeder conduits, equipment frames, instrument transformers and switch rooms to a grounding mat.
  6. Install a continuous substation room perimeter ground bus, exposed on room walls, unless otherwise indicated.
  7. Install an additional grounding electrode conductors where the total length of the main grounding bus exceeds 100 feet, and for each additional foot or part thereof. Evenly space. These grounding electrode conductors shall be at least No. 4/0 AWG bare stranded copper wire in continuous unspliced lengths.
  8. At least two (2) grounding electrode conductors shall be provided to bond the main grounding bus to building steel. Each substation incoming line section, transformer section and secondary switchgear section shall be connected to the main grounding bus.
  9. In all cases, the grounding electrode conductor shall be securely bonded to its enclosing conduit at both ends of each run.
  10. Busway Supply Circuits: Install separate equipment grounding conductor from the grounding bus in the switchgear, switchboard, or distribution panel to equipment grounding-bar terminal on busway.
  11. Isolated Grounding-Receptacle Circuits: Install a separate insulated equipment grounding conductor connected to the receptacle grounding terminal. Isolate grounding conductor from raceway and from panelboard grounding terminals.

H.Outdoor Equipment Grounding:

  1. Each outdoor switchgear and substation shall be provided with a suitable ground grid to form a mat covering the entire area of the switchgear or substation. This mat shall consist of a continuous stranded bare copper cable connected to driven ground rods. The size of ground conductors shall be determined by the maximum available fault current but shall not be less than No. 4/0 AWG.
  2. All outdoor switches or bus structures, cable sheaths, potheads, equipment frames, conduits, etc., and building steel, shall be effectively grounded to the mat.
  3. Steel fence enclosures, etc., surrounding an outdoor substation shall be grounded. A ground conductor of a minimum No. 4/0 AWG bare copper wire shall be installed around the fence approximately 12 inches below grade and 12 to 24 inches from the fence. The wire shall be connected to ground rods installed at each corner and at intervals of approximately 20 feet around the fence. The fence posts and fence shall be connected to the grounding wire at each ground rod. All gates shall be bonded to the fence with flexible braided copper jumpers having cross sectional area equal to the grounding conductors. When the fence is separated from the station equipment or structure, the fence shall be bonded to the building steel, unless another method is required by the utility company.

I.Metal Poles Supporting Outdoor Lighting Fixtures: Ground pole to a grounding electrode in addition to separate equipment grounding conductor run with supply branch circuit.

J.Connections to Lightning Protection System: Bond grounding conductors, including grounding-conductor conduits, to lightning protection down conductors or lightning protection grounding conductors in compliance with NFPA 780.

K.Common Ground Bonding with Lightning Protection System: Bond electric power system ground directly to lightning protection system grounding conductor at closest point to electric service grounding electrode. Use bonding conductor sized same as system grounding conductor and install in conduit.

3.1APPLICATION

  1. Separately Derived Systems: Provide grounding for separately derived systems according to NEC 250-26.

3.2INSTALLATION

  1. General:
  2. Provide copper conductors only.
  3. Install a separate equipment grounding conductor for each all branch circuit.
  4. Routing: Route along the shortest and straightest paths possible or as otherwise indicated. Avoid obstructing access or placing conductors where they may be subjected to strain, impact, or damage.
  5. Underground Grounding Conductors: Unless otherwise indicated, provide bare copper wire buried at least 24 inches below grade.
  6. Ground Rods: Install according to NEC requirements, except where Drawings or Specifications exceed NEC requirements.

3.3CONNECTIONS

  1. General: Make connections to minimize galvanic action or electrolysis. Select connectors, connection hardware, conductors, and connection methods for compatibility.
  2. Use electroplated or hot-tin-coated materials.
  3. Make connections with clean, bare metal at points of contact.
  4. Coat and seal connections between dissimilar metals with inert material to prevent penetration of moisture.
  5. Exothermic-Welded Connections: Use for connections made underground, and from foundation reinforcing steel to structural steel at columns indicated. .
  6. Comply with manufacturer's written instructions.
  7. Welds that are puffed up or indicating improper cleaning are not acceptable.
  8. Wire Terminations:
  9. Terminate #10AWG and smaller conductors with winged pressure-type connectors.
  10. Terminate #8AWG and larger conductors with pressure-type grounding lugs.
  11. Screw and Bolt Connections:
  12. Tighten screws and bolts according to manufacturer's published torque values.
  13. Use UL486A and UL486B where manufacturer's torque values are not available.
  14. Compression-Type Connections:
  15. Use hydraulic compression tools to provide correct circumferential pressure.
  16. Use tools and dies recommended by manufacturer of connectors.
  17. Provide an embossing die or other standard method to make a visible indication that compression has been adequate.

3.4FIELD QUALITY CONTROL

  1. Tests:
  2. Perform resistance to ground tests according to the IEEE81, 2-point method.
  3. Perform earth resistance measurements not less than two full days after the last trace of precipitation, without additional of moisture by any means other than natural drainage or seepage, and without chemical treatment or other means of reducing resistance.
  4. Excessive Ground Resistance: Where resistance exceeds specified values, notify Owner promptly and make recommendations to reduce ground resistance to specified values.
  5. System maximum grounding resistance value shall not exceed 5 ohms.
  6. Individual ground rod resistance shall not exceed 25 ohms.

END OF SECTION

Page 1 of 6

Revision Date: 01/21/14 Project & Bid Package

File name: 260526 GROUNDING AND BONDING FOR ELECTRICAL SYSTEMS