General Construction Specifications
PART 1 - GENERAL
01 SECTION INCLUDES
A. Power system grounding.
B. Electrical and raceway grounding and bonding.
C. Communication system grounding.
02 SYSTEM DESCRIPTION
A. Ground the electrical service system neutral at service entrance to metallic water service to supplementary grounding electrode, and metal building frame where available.
B. Ground each separately-derived system neutral.
C. Bond together system neutrals, service enclosures, exposed non-current carrying metal parts of electrical equipment, metal raceway systems, grounding conductor in raceways and cables, receptacle ground connectors, and plumbing systems.
D. Provide communications system grounding conductor at point of service entrance and connect to building electrical service ground.
PART 2 - PRODUCTS
03 MATERIALS
A. Ground Rods: Copper-encased steel, 5/8 inch diameter, minimum length 10 feet, equal to Copperweld.
B. All grounding conductors, bonding jumpers, connectors, etc. shall be copper and UL listed for use in grounding systems.
PART 3 - EXECUTION
04 INSTALLATION
A. Provide a separate, insulated grounding conductor in feeder and branch circuits. Terminate each end on a grounding lug, bus, or bushing.
B. Connect grounding electrode conductors to metal water pipe using a suitable ground clamp. Make connections to flanged piping at street side of flange. Provide bonding jumper around water meter.
C. Supplementary Grounding Electrode: Use minimum of 20 feet No. 4/0 bare copper wire embedded in concrete foundation and bonded to reinforcing steel. Bond to a structural steel column where available, and as indicated on the drawings.
D. All connections other than bolted terminations on ground buses, grounding lugs and bushings or connections to metal water pipe shall be made using exothermic welds, equal to Cadweld, suitable for the type of connection required. Use UL listed grounding pipe clamp for water pipe connection.
E. Ground the secondary neutrals of 480 volt primary/208 or 240 volt secondary transformers to an effectively grounded domestic water pipe or to effectively grounded structural steel frame. If neither of the above is available, encase 20 feet of bare copper wire, sized to match the required grounding jumper, in the nearest concrete foundation, bond to reinforcing steel, and extend to transformer. Transformer grounding jumpers shall be sized as follows:
SECONDARY TRANSFORMER GROUNDING
VOLTAGE CAPACITY JUMPER (AWG)
208Y/120 Less than 30 KVA #8
3 Phase 30 KVA #6
45 KVA #4
75 KVA #2
112.5 KVA #1/0
150 and 225 KVA #2/0
300 KVA and above #3/0
F. Use minimum 6 AWG copper conductor for communications service grounding conductor. Leave 10 feet slack conductor at terminal board.
05 FIELD QUALITY CONTROL
A. Field inspections and testing shall be in accordance with applicable Sections of Division 1.
B. Inspect grounding and bonding system conductors and connections for tightness and proper installation.
C. Measure ground resistance from system neutral connection at service entrance to ground reference points using suitable fall-of-potential type ground testing equipment. Resistance shall not exceed 1 ohms.
D. Measure ground resistance from each ground rod to ground reference points using suitable fall-of-potential type ground testing equipment. If resistance is greater than 25 ohms, drive additional ground rods, spaced 10 feet apart and bonded to the first ground rod as required to achieve a resistance of 25 ohms or less.
END OF SECTION
