6 December 2006
Including change 1, 7 December 2006
Grounding Cluster Bars. Use to connect phase and neutral conductor
jumper cables to the selected method of providing a ground electrode (pole ground wire,
temporary ground rods, substation ground grid). Cluster bars must have an attached
bonding lead. Provide temporary ground rods as stated in Table 7-2.
Table 7-2. Temporary Ground Rod Minimum Requirements
1. Single rod installed to a depth of 5 ft (1.5 m) below grade.
A minimum 5/8 in (16 mm) diameter bronze, copper, or copper-weld rod at
least 6 ft (1.8 m) long.
A 6 ft (1.8 m), screw-type ground rod, consisting of a minimum 5/8 in (16 mm)
diameter copper-weld shaft with a bronze auger bit and bronze T-handle,
tightly connected to the rod.
2. Additional rods to provide a total of 5 ft (1.5 m) below grade where required.
Install 6 to 8 ft (1.8 to 2.4 m) apart while maintaining the 10 ft (3 m) step and
touch potential clearance.
Bond all rods together prior to installing other electrode connections.
Equipotential Zone. All metal within reach must be at the same (zero or
minimum) potential with reference to ground in order to safely protect the workers.
Install and connect grounding and bonding conductors in a proper manner to provide an
equipotential zone of protection for workers.
Ground Connection and Electrodes. Temporary grounds must be
connected to the permanent ground of the structure or pole, to another grounding
electrode or grounded conductor. This may be the neutral conductor, or an overhead
ground wire, or the station ground, or one or more temporarily driven ground rods,
driven so at least 6 ft (1.8 m) of the ground rod is in contact with moist soil. Additionally,
any metallic object that is a good conductor, such as an anchor rod or permanent
ground rod, which extends several feet into the ground, may be used for the connection
if sufficiently low ground resistance is determined. When connecting to a metal pole or
structure, always verify it has an unbroken connection to its permanent ground rod.
Temporarily driven ground rods are required as temporary ground connections for work
on wood poles. In areas accessible to unauthorized personnel, provide a barricade for
the ground rod as a physical and visual barrier to prevent anyone from approaching
within the minimum approach distances specified in Table 3-1.
TEMPORARY GROUNDING OF SUBSTATION CURRENT-CARRYING
EQUIPMENT COMPONENTS. Ground deenergized current-carrying components of
substation equipment before approaching them within working clearance distances.
Grounds shall be placed as close to the equipment/work as practical to minimize the
inductive voltage loop formed by the ground cable and the worker. Special precautions
are needed during oil handling. Refer to Figure 7-1, and Tables 7-3 and 7-4. Refer to
Table 7-5 if oil handling is involved.