26 05 26 - Grounding And Bonding For Electrical Systems.pdf

WVA Specifications for Grounding and Bonding for Electrical Systems

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SECTION 26 05 26

GROUNDING AND BONDING FOR ELECTRICAL SYSTEMS

PART 1 - GENERAL

1.1 DESCRIPTION

A. Scope:

1. CONTRACTOR shall provide labor, materials, equipment, and incidentals as shown, specified, and required to furnish and install complete grounding for electrical systems, structures, and equipment.

1.2 REFERENCES

A. Standards referenced in this Section are:

1. ASTM B8, Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard or Soft.

2. ASTM B189, Specification for Lead-Coated and Lead-Alloy-Coated Soft

Copper Wire for Electrical Purposes.

3. UL 467, Grounding and Bonding Equipment.

4. NETA Acceptance Testing Specifications.

1.3 QUALITY ASSURANCE

A. Qualifications:

1. Field Acceptance Testing Firm: Retain service of independent testing firm that shall perform acceptance field testing of grounding system. Testing firm shall have experience in testing grounding systems and shall be member company of

NETA.

B. Regulatory Requirements

1. National Electrical Code, (NEC).

a. NEC Article 250, Grounding and Bonding.

1.4 SUBMITTALS

A. Action Submittals: Submit the following:

1. Shop Drawings:

a. Listing of grounding connector types identifying where each is to be used.

b. Layouts of each structure’s ground grid.

c. Test point construction details.

2. Product Data:

a. Manufacturer’s technical information for grounding materials proposed.

3. Testing Plans:

a. Ground resistance test procedure.

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B. Informational Submittals: Submit the following:

1. Field Quality Control Submittals

a. Results of ground resistance tests at each test point.

PART 2 - PRODUCTS

2.1 MATERIALS

A. Bare Ground Cable:

1. Material: Soft drawn bare copper stranded cable conforming to ASTM B8 and

ASTM B189. No. 4/0 AWG minimum size unless otherwise noted on the

Drawings.

2. Manufacturers: Provide products of one of the following:

a. Cablec Corporation.

b. General Cable Corporation.

c. Southwire Cable Company.

d. Or equal.

B. Ground Rods:

1. Material: Copper-clad rigid steel rods, 3/4-inch diameter, ten feet long.

2. Manufacturers: Provide products of one of the following:

a. Copperweld, Bimetallics Division.

b. ITT Blackburn Company.

c. Or equal.

C. Grounding Connectors:

1. Material: Pressure connectors shall be copper alloy castings, designed specifically for items to be connected and assembled with Durium or silicone bronze bolts, nuts, and washers. Welded connections shall be by exothermic process utilizing molds, cartridges, and hardware designed specifically for connection to be made.

2. Products and Manufacturers: Provide one of the following:

a. Pressure Connectors:

1) O.Z./Gedney, Division of General Signal Corporation.

2) Burndy Corporation.

3) Or equal.

b. Welded Connections:

1) Cadweld by Erico Products, Incorporated.

2) Therm-O-Weld by Burndy Corporation.

3) Or equal.

D. Ground system components shall conform to UL Standard 467.

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PART 3 - EXECUTION

3.1 INSPECTION

A. Examine conditions for the Work and notify CONTRACTING OFFICER in writing of conditions detrimental to proper and timely completion of the Work. Do not proceed with Work until unsatisfactory conditions have been corrected.

3.2 STRUCTURE GROUND SYSTEM

A. Provide ground grids as shown on the Drawings.

B. Install No. 4/0 bare copper cable around the exterior perimeter of structures at minimum of 2.5 feet below grade, unless otherwise shown or indicated on the

Contract Documents.

C. Connect grids to continuous underground water pipe system, when practical.

D. For new structures with concrete foundation or footing, connect structure’s reinforcing steel or other concrete-encased electrode to grounding grid.

E. Provide accessible test points for measuring the ground resistance of each grid.

F. Weld all buried connections except for test points.

3.3 EQUIPMENT GROUNDING

A. Ground electrical equipment in compliance with Laws and Regulations and the

Contract Documents.

B. Equipment grounding conductors shall be bare stranded copper cable of adequate size installed in metal conduit where required for mechanical protection. Ground conductors, pulled into conduits with non-grounded conductors, shall be insulated.

Insulation shall be green.

C. Control panels grounding conductors shall be bare stranded copper cable of adequate size to ground grid from AC ground bus, and an insulated stranded copper cable of adequate size to ground grid from DC ground bus.

D. Connect ground conductors to conduit with copper clamps, straps, or with grounding bushings.

E. Connect to piping by welding or brazing. Use copper bonding jumpers on gasketed joints.

F. Connect to equipment by means of lug compressed on cable end. Bolt lug to equipment frame using holes or terminals provided on equipment specifically for

2118173 26 05 26-4 grounding. Do not use hold-down bolts. Where grounding provisions are not included, drill suitable holes in locations recommended by equipment manufacturer or designated by CONTRACTING OFFICER.

G. Connect to motors by bolting directly to motor frames, not to soleplates or supporting structures.

H. Connect to service water piping by means of copper clamps. Use copper bonding jumpers on gasketed joints.

I. Scrape bolted surfaces clean and coat with conductive oxide-resistant compound.

3.4 FIELD QUALITY CONTROL

A. Test completed ground systems for resistance to ground using an electrical three terminal ground resistance tester. Test all grounded cables and metal parts for continuity of connection. Testing shall be witnessed by CONTRACTING OFFICER.

B. Grounding system maximum resistance shall not exceed five ohms under normally dry conditions when measured by resistance tester. Resistance values above five ohms shall be brought to CONTRACTING OFFICER’s attention. Provide additional ground rods if necessary to attain a resistance to ground of less than five ohms for each ground grid. Grounding additive shall be added when installing additional ground rods to increase their effectiveness.

C. Acceptance Testing:

1. Perform acceptance testing of grounding system. Testing shall be performed by testing firm in accordance with latest NETA Acceptance Testing

Specifications.

2. Test Equipment, Calibration and Reporting: Test equipment, instrument calibration, and test reports conform to latest edition of NETA acceptance testing specification.

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