260526 - ELECTRICAL GROUNDING.pdf

TABLE OF CONTENTS

SECTION 260526 – ELECTRICAL GROUNDING

PART 1 - GENERAL

1.1 REFERENCES

1.2 SCOPE

1.3 SHOP DRAWING SUBMITTALS

PART 2 - PRODUCTS

2.1 EQUIPMENT GROUNDS

2.2 GROUND FAULT PROTECTION

2.3 GENERAL USE GROUND BUSSES

2.4 MATERIALS

PART 3 - EXECUTION

3.1 INSTALLATION - GENERAL

3.2 EQUIPMENT GROUNDS

3.3 IDENTIFICATION

3.4 TESTS

BETHANY MIDDLE SCHOOL JUNE 6, 2025

FIRE PUMP REPLACEMENT VAN ZELM #2024090.00

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SECTION 260526 - ELECTRICAL GROUNDING

PART 1 - GENERAL

1.1 REFERENCES

A. This Section covers the specification of grounding for electrical equipment and systems. Refer to Section – COMMON WORK RESULTS FOR ELECTRICAL WORK, GENERAL CONDITIONS, SUPPLEMENTARY CONDITIONS, applicable Sections of DIVISION 1, and all other project instructions for other requirements.

B. THIS PROJECT WILL BE COMMISSIONED. REFER TO COMMISSIONING

SPECIFICATION SECTIONS FOR COMMISSIONING INFORMATION AND

REPSONSIBILITIES. THE COMMISSIONING PROCESS WILL REQUIRE ADDITIONAL

LABOR, MATERIAL AND/OR OTHER COSTS WHICH MUST BE PROVIDED BY THE

CONTRACTOR AS PART OF THIS PROJECT.

1.2 SCOPE

A. Provide labor, materials, services, equipment and transportation necessary for complete and operational grounding systems as indicated on Contract Drawings and specified herein, including but not limited to following:

1. Equipment grounds

2. Ground fault protection

3. Building and piping ground system

4. Systems Commissioning

1.3 SHOP DRAWING SUBMITTALS

A. Submit for review shop drawings for the following:

1. Ground rods

2. Bus

3. Bushings and pressure lugs

4. Pipe clamps

5. Circuit breakers

6. Grounding conductors

7. Receptacles

8. Plug-in tester unit

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PART 2 - PRODUCTS

2.1 EQUIPMENT GROUNDS

A. Provide green insulated copper equipment grounding conductor between the ground bus of the source distribution panel or switchboard and each load being served. Conductor shall be sized according to NEC Article 250, Table for “Minimum size of Equipment Grounding Conductors”.

B. Provide separate grounding conductor for each branch circuit.

2.2 GROUND FAULT PROTECTION

A. If excessive ground current flows in feeders to 480 V main switchboard, main breakers and/or circuit breakers with ground fault sensing shall trip to protect switchboard against arcing ground faults.

B. Provide ground fault circuit interrupter protection for receptacles as required and indicated.

2.3 GENERAL USE GROUND BUSSES

A. Provide ground busses where shown and/or indicated. Busses shall be pre-drilled, with standard NEMA two-bolt hole sizing and spacing, 1/4” thick by 4” wide by 18” long (minimum). Bus bar shall be electro tin plated copper, and include thermoset polyester insulators, and steel mounting brackets.

B. Bonding and Grounding Jumper Cable

1. Provide products meeting the requirements of the Drawings and Specifications, Belden No. 8669 or equivalent.

2. Jumper cable shall be hollow braided, 60 Amp capacity, copper.

3. Jumpers shall have compression or exothermic type terminals on both ends of cables.

Terminals shall be compatible with jumper cable material and equipment material in order to not have any degenerative reaction.

2.4 MATERIALS

A. Ground rods shall be 3/4” x 10’-0” copper-clad steel, by Carolina or acceptable equivalent.

Galvanized steel ground rods are not acceptable.

B. Below-grade and concealed connections shall be exothermic weld type, Thermweld, Cadweld or acceptable equivalent. Above-grade and exposed connections shall be compression type, installed with hydraulically operated tools, Burndy or acceptable equivalent.

C. Wire shall be stranded bare copper or insulated copper, as indicated on Contract Drawings.

D. Bus shall be copper bar, as indicated on Contract Drawings.

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E. Grounding Bushings and Pressure Lugs shall be bronze or copper alloy by T&B, O.Z./Gedney or acceptable equivalent.

F. Pipe grounding clamps shall be bronze or coppery alloy by T&B, O.Z./Gedney or acceptable equivalent.

PART 3 - EXECUTION

3.1 INSTALLATION - GENERAL

A. Refer to SECTION 260515, BASIC MATERIALS & METHODS - ELECTRICAL.

B. Grounding shall be installed and tested in accordance with NEC (NFPA 70) and to satisfaction of local electrical inspector and Architect.

C. If outlet is located within six feet of edge of sink or water source; GFCI/GFI receptacles shall be used.

3.2 EQUIPMENT GROUNDS

A. Equipment grounds shall be continuous from ground bus to electrical equipment and devices.

B. Provide equipment grounds for electrical equipment furnished or installed as part of this Contract.

C. Grounded service conductor (neutral) of 480Y/277 V distribution system shall be grounded at only one point: neutral connection to the ground bus. Under no circumstances shall system neutral be grounded at any other point. As part of final inspection procedures, demonstrate purity of system neutral.

D. Regardless of rating or length, circuits run in FMC shall carry grounding conductor for that portion of circuit in FMC; bond conductor at each end.

E. Current return conductors (neutrals), which are grounded at the source, shall NOT be used for equipment grounding. Provide separate conductors for equipment grounding; refer to SECTION 260515, paragraph on IDENTIFICATION, for color requirements.

F. Grounding conductor shall be secured to equipment enclosure at power source (usually to a ground bus) and at apparatus being served by AC supply. Grounding conductors shall be insulated and shall be large enough to carry ground fault current safely.

G. Provide following for panelboards: neutral bus insulated from enclosure; and grounding bus bonded to enclosure. Grounding bus shall have means for termination of grounding conductors to panelboard cabinet.

H. Maintain electrical continuity of raceways by the following means:

1. Threaded fittings with joints made up wrench-tight where threaded rigid conduit is used.

2. Threadless fittings made up tight.

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3. Metal bushing inside and locknut outside of metal boxes and cabinets when threaded conduit is used. If outside locknut is inaccessible for tightening after installation, provide additional locknut inside. If bushing is composed entirely of insulating material, use locknuts inside and outside.

4. Bonding jumper across joints of wireways, cable trays, expansion or deflection fittings, etc.

5. Devices listed for the purpose by UL.

I. NOTE: Addition of equipment grounding conductor to AC circuits run in metallic enclosures does NOT lessen the requirement for conductor enclosure continuity, since part of total ground fault current will flow through the raceway and enclosure system. Therefore, the continuity of this system shall be maintained.

J. Bond neutrals of each 208Y/120 V distribution transformer to ground so as to be separately derived system and shall be grounded locally to building steel. If building steel does not exist (i.e., concrete structures), the transformer shall be grounded to main service ground bus.

Transformer ground shall also be bonded to nearest available local metal water pipe. The primary feeder ground is supplemental and shall be sized for primary feeder protection. Refer to contract drawings for additional bonding requirements.

3.3 IDENTIFICATION

A. Engrave nameplates of receptacles wired to GFI breakers to read "GFI" adjacent to or above receptacle opening.

3.4 TESTS

A. Acceptance testing for electrical grounding systems, specified herein, shall be performed by independent testing firm with minimum ten years experience in testing the specified items.

Firm shall be member of International Electrical Testing Association (INETA).

B. Testing procedures shall be as described in INETA "Acceptance Testing Specifications" (ATS).

C. Testing firm shall immediately notify Contractor and Engineer, of any deficiencies requiring correction before electrical system is placed in service and shall confirm information in writing within five days.

D. Discrepancies found shall be corrected by firm which installed switchboard. However, testing firm shall make minor field adjustments that may be found necessary.

E. Test report shall include typewritten test results on firm's standard test forms.

F. Test and inspect the main grounding electrode system in accordance with Section 7.13 of the NETA Acceptance Testing Specification. Perform a resistance to ground test and ensure that resistance is no greater than 5 (five) ohms. Investigate and supplement grounding system where resistance exceeds recommended values and re-test as required.

G. Ground Fault Circuit Interruption shall be tested after installation by random connection of plug-in tester to various protected receptacles, as directed by Architect.

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H. All ground fault systems including but not limited to the main service overcurrent protective device ground fault protection equipment shall be performance tested when first installed on site per manufacturer’s instructions and Section 7.14 of the NETA Acceptance Testing Specifications Inspection and Test Procedures for Ground-Fault Protection Systems. Tests shall include, but not be limited to, resistance measurements through all bolted connections, insulation resistance test on all control wiring and pick up tests using primary injection.

END OF SECTION