E24.REV

GROUNDING SYSTEM

NOTE: FINAL COPY: JUNE, 1988.

Part 1 -	GENERAL

1)	WORK INCLUDED

NOTE: THE FOLLOWING ARE NOT ALL INCLUSIVE. ADD OR DELETE SYSTEMS NOT APPLICABLE TO A PARTICULAR PROJECT. PROVIDE LONGER AND/OR MORE GROUND RODS THAN SPECIFIED. ALSO PROVIDE SOILS SUCH AS ROCK AND SANDY SOILS

A.	Work in this Section includes the providing of labor, materials, equipment and services necessary for a complete and safe installation in accordance with the contract documents and all applicable codes and authorities having jurisdiction for the following:

1.	Grounding service drops, underground distribtuion, outdoor substations, service and equipment and systems noted.

2)	RELATED WORK AND REQUIREMENTS

A.	Requirements of GENERAL CONDITIONS, DIVISION No. 1 and Section GENERAL PROVISIONS FOR ELECTRICAL WORK apply to all work in this Section.

NOTE: EDIT TO SUIT PROJECT REQUIREMENTS. INCLUDE ONLY SECTIONS DIRECTLY AFFECTING WORK OF THIS SECION

B.	Related work in the following Sections:

1.	CABLE TRAY (CENTER SPINE TYPE).

2.	CABLE TRAY (SIDE RAIL TYPE).

3.	WIRE AND CABLE.

4.	BUSWAYS.

5.	LOW VOLTAGE DISTRIBUTION EQUIPMENT.

6.	MEDIUM VOLTAGE SWITCHGEAR.

7.	UNIT SUBSTATION.

8.	MOTOR CONTROL CENTERS.

9.	MOTOR CONTROLLERS.

10.	ELECTRIC SERVICE SYSTEM.

11.	POWER, CONTROL AND ALARM WIRING SYSTEMS.

12.	DEVICES.

13.	LIGHTING FIXTURES.

14.	PIPE TRACING SYSTEM.

15.	-----.

3)	REFERENCE STANDARDS

A.	Published Specifications' standards, tests or recommended methods of trade, industry or governmental organizations apply to work in this Section.

B.	Comply with all applicable national, state and local codes and refer to Section GENERAL PROVISIONS FOR ELECTRICAL WORK for additional Reference Standards.

4)	QUALITY ASSURANCE

A.	Refer to Section GENERAL PROVISIONS FOR ELECTRICAL WORK for Guarantee and other Quality Assurance requirements.

5)	SUBMITTALS

A.	Submit shop drawings for all equipment provided under this Section.

Part 2 -	PRODUCTS

1)	COPPER CONDUCTORS

A.	Provide copper conductors as follows:

1.	Service shall be insulated, 25 percent of service capacity, maximum 1-500 MCM per service in rigid metallic conduit.

2.	Service shall be bare bus, 25 percent of service capacity, maximum 4 inch x 1/4 inch bar.

3.	Emergency distribution shall be insulated, 25 percent of distribution capacity, in rigid metallic conduit.

4.	Y-connected transformer center taps shall be insulated, 25 percentof transformer capacity, maximum 1-500 MCM in rigid metallic conduit.

5.	Telephone service equipment shall be insulated, No. 6 in rigid metallic conduit.

6.	Fire alarm control panel shall be insulated, 25 percent of service capacity, in rigid metallic conduit.

7.	Lightning protection shall be the same as lightning system conductors.

NOTE: FOR 5 KV AND UP, WHERE APPLICABLE.

8.	Primary switches shall be bare 1/0.

9.	Outdoor metallic equipment and hardware shall be bare 1/0.

10.	Metallic raceway continuity shall be bare No. 6.

NOTE: FOR METALLIC STRUCTURE AND SUBSTATION GRIDS.

11.	Underground grids shall be bare 4/0.

NOTE: FOR SERVICE DROPDOWN CONDUCTOR.

12.	Terminal pole shall be bare; conductors 25 percent of service capacity.

2)	GROUND CLAMPS

A.	Provide bronze, solderless type with bronze screws, suitable for receiving noted conductors.

NOTE: CHECK SOIL CONDITION.

3)	GROUND RODS

A.	Provide ground rods as follows:

1.	10 ft by 3/4 inch diameter copperweld.

2.	10 ft by 3/4 inch diameter solid copper.

4)	BONDING TREES

A.	Provide bonding trees as approved.

5)	POLE MOUNTED ARRESTORS

A.	Provide intermediate duty type, suitable for voltage application.

Part 3 -	EXECUTION

1)	INSTALLATION

NOTE: APPLIES TO POLE LINE SERVICES.

A.	Service drop:

1.	Ground the following:

a.	Service: Through arrestors to driven ground rods 2 ft. below finished grade.

b.	Service: Through arrestors to underground serpentine conductor grid.

c.	Neutral: To grounding conductor, below arrestors.

d.	Metallic structure: to underground serpentine conductor grid.

NOTE: INDICATE ON DWGS.

2.	Serpentine conductor grid: maximum 16 ft spacing, extending 6 ft. from base of structure in all directions.

3.	Protect down conductors with nonmetallic cover extending up to 10 ft. above finished grade.

B.	Underground distribution:

1.	Ground the following:

a.	On site, outdoor electrical equipment to driven ground rods.

b.	Interrupted metallic raceways with ground conductors connected to metallic raceway at each end.

c.	Vault equipment and wiring, through bonding trees to driven grounds rods including cable shielding, cable sheathing, metallic raceways, hardware and grounding conductors.

d.	Manhole equipment and wiring through bonding trees to driven ground rods including cable shielding, cable sheathing, metallic raceways, hardware and ground conductors.

e.	Handhole hardware to driven ground rods.

2.	Provide vertically driven ground rods with tops 2 ft. below finished grade.

C.	Outdoor substations:

1.	Ground the following to ground grid:

NOTE: APPLIES TO PRIMARY SWITCHES WITH GROUND TERMINALS.

a.	Primary switches and arrestors, center tap of Y-connected transformers through substation secondary neutral and ground bus, secondary neutral bus through ground bus at ends, and yard fence and gate at corners.

2.	Inaccessible connections shall be cadwelded.

NOTE: INDICATE ON DWGS.

3.	Ground grid the following:

a.	Serpentine conductor 16 ft. on centers in both directions. Connect at intersections.

b.	4 groups of 3 interconnected driven ground rods connected to serpentine conductors. Locate at corners of grid.

D.	Service and equipment:

1.	Ground the following: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

NOTE: FOR SEPARATELY MOUNTED SERVICE SWITCHES.

a.	Neutral conductor through disconnecting link and ground terminal to water service ground clamp and driven ground rods.

NOTE: FOR SERVICE SUBSTATION.

b.	Center tap of Y-connected transformers through secondary neutral and ground bus to water service ground clamp and driven ground rods.

NOTE: FOR SERVICE SWITCHBOARDS AND SUBSTATIONS.

c.	Neutral bus to ground bus at ends and ground bus to water service ground clamp and driven ground rods.

2.	Mount ground clamp on water service at street side of main service valve.

NOTE: APPLIES TO OUTDOOR WATER METERS.

3.	Provide jumper to by-pass water meter.

NOTE: APPLIES WHERE WIRED GROUNDING CONDUCTOR IS USED.

4.	Run insulated ground conductor in rigid metallic conduit with conductor connected to conduit, through ground fitting at each end.

NOTE: APPLIES WHERE BUS GROUNDING CONDUCTOR IS USED.

5.	Fasten ground bus to building 5 ft. on centers. Connections between sections: nonferrous bolts, nuts, flat and belleville washers.

a.	Connect bus to water service.

b.	Connect bus to water service and driven ground rods.

NOTE: FOR INDIVIDUAL TRANSFORMERS THROUGHOUT BUILDING.

6.	Separately ground center taps of Y-connected transformers to:

a.	Grounding conductor.

b.	Ground bus.

c.	Building steel.

7.	Ground at service entrances:

NOTE: FOR HIGH VOLTAGE, SHIELDED CABLES.

a.	Cable shielding.

NOTE: FOR METALLIC COVERED CABLES SUCH AS LEAD.

b.	Cable sheathing.

c.	Service equipment including ground straps and jumper.

8.	Ground noncurrent carrying metal parts of distribution panels, switchboards, transformer enclosures, raceways, busway enclosures, controller enclosures, motor frames, and other electrical equipment.

E.	Miscellaneous grounding:

1.	Ground the following:

a.	Telephone system.

b.	Fire alarm system.

c.	Emergency distribution system.

d.	Lightning protection system.

e.	Computer equipment.

f.	Fire line telephone system.

g.	Smoke detection system.

h.	Trench header and cellular floor system.

2)	TESTS

A.	For ground continuity at switchboards, transformers, and panel boards.

B.	Provide written certification of compliance.