SECTION 3 GROUNDING LINES and EQUIPMENT
General
3.0
Temporary protective grounds shall be placed as close to the work as possible to assist in
obtaining Equal Potential Zone (EPZ). (See Protective Ground Procedures section).
3.1
*Whenever possible, a ground shall be placed on all phase conductors at the point of work to
obtain EPZ. When grounding at the point of work creates congestion and/or is a hazard to
workers, grounds shall be placed on each side as near as possible to where the work is being
performed (For Transmission only, this requires Supervisor Approval and to be documented on
Job Briefing as to “why”).
Note: Grounds may be removed for testing purposes, provided employees use protective equipment and
treat as energized at test voltage. Grounding may be a part of the clearance process or may be
required to be installed as a part of the work process.
3.2
Proper flame retardant clothing shall be worn when attaching portable grounds.
3.3
*When work is to be performed on conductors or equipment that has been de- energized all phases
of the circuits shall be properly grounded and bonded together or the work performed as
energized. All grounds shall be flagged with a company flag that indicates grounds are installed.
3.4
Any equipment or system neutral not grounded shall be grounded before work is started.
CAUTION: ANY OPEN POLE GROUNDS OR UN-BONDED POLE GROUNDS SHALL BE
CONSIDERED ENERGIZED UNTIL A CHECK PROVES OTHERWISE.
3.5
When installing or removing protective grounds, the grounded end shall be installed first and
removed last. Except for rolling type grounds and the circuits insulated for voltages under 600
volts, live line tools shall be used when making and removing ground connections to lines or
equipment.
3.6
If work is to be performed at more than one location in the line section, the conductor to be
worked on shall be grounded at each work location.
3.7
*When a grounding set has received a fault current, the set shall be tested and if can not be
repaired, the set shall be destroyed.
3.8
When grounding phases consisting of more than one conductor per phase, a short bonding cable
made of the same material as the grounding cable shall be used or a ground cable could be used on
each wire to tie conductors in a bundle phase together. Space assemblies shall not be considered
adequate bonding of bundled conductors.
3.9
*Grounds may be removed for equipment testing purposes but work on the equipment not
associated with the test shall be stopped by the person doing the testing until the grounds are
replaced. Except for moving type grounds, live line tools shall be used when making and
removing ground connections to lines or equipment. During the test procedure, the employee
shall be insulated and/or insolated from any hazards involved. The employee shall be protected in
the event the previously grounded lines and equipment become energized.
3.10
*Personal protective grounds shall not be obtained through a switch, transformer, breaker, etc…
3.11
*Equipment ground cable on equipment such as digger derricks and stringing equipment shall be
completely uncoiled while in use.
*Note: Where excess slack in the ground cable may exist, access should be limited due to the movement of
the cable should a fault occur.
3.12
After obtaining proper clearances, crews working on distribution or transmission voltages and/or
substation equipment shall use grounds in sufficient number and in such sequence so that at no
time during the course of the work being done can an employee come within accidental contact
distance (including items being handled) of the ungrounded conductors. (Refer to Table R6)
3.13
On metal structures, conductors shall be considered as bonded together and grounded when each
is separately grounded to the structure.
3.14
A system neutral, ground wire or a static shield wire shall not be opened until the proposed
opening has first been jumped or bypassed.
3.15
Grounds under the control of the Dispatcher shall be removed only under his/her instructions.
3.16
Approved grounding clamps must be of sufficient size to withstand the maximum fault current
magnitude and duration available at the work location
3.17
*All equipment and protective grounds shall have the cable jacket supported and compression
type ferrules installed at each end.
*Exception: Cables that are too small to accommodate ferrules.
Transmission Line Grounding
*Note: See Protective Grounding Procedures section
Substation Grounding
3.18 *Protective grounding cables shall be an approved ANSI ground cable, minimum of 4/0 copper.
3.19
*While working in substations if any part of the hoist, crane or other lifting devices and equipment
whether being used or not that can come within the minimum approach distances set in Table R6 it
shall be grounded.
3.20
*Substation buses and equipment de-energized for repairs or changes shall be grounded on both
sides of the work area this would include new grounds applied at each new open point.
*NOTE: See Protective Grounding Procedures section for 3.20
The grounds shall be a minimum of 4/0 copper unless studies have shown that larger conductor sizes are
needed.
3.21
Temporary grounds shall be removed as the last phase of clean up.
Distribution Line Grounding
3.22
Whenever possible, a ground shall be placed on all phase conductors at the point of work. When
equipotential grounding is not an option, grounds shall be placed on each side as near as possible
to where the work is being performed.
*See Distribution: Protective Grounding Procedures section.
3.23
*When working between two open switches on a distribution line section that is part of a
clearance, all known potential sources that can generate a back feed into the clearance area must
be cleared and tagged. Additional grounds shall be installed as close to the open point(s) as
possible in addition to the working grounds.
Exception: Where multiple known sources exist; a single source ground can be used on that side
of the work site if it can be installed between those source points and the work site. The source
ground(s) shall be installed as close to the source(s) as practical
3.24
On wood structures and equipment with ground wires or grounded neutrals, the safety grounds
may be connected to these ground wires or grounded neutrals. On structures without ground wires
or grounded neutrals, a temporary driven ground, preferably 25 feet away from any area where
anyone is likely to be, may serve as the ground. When structure grounds are being depended upon
to provide safety grounding, ground continuity should be visually checked.
Underground Grounding
3.25
*All existing installations of underground cables and equipment shall be considered energized at
all times unless properly disconnected from all sources of potential, tested for potential, and then
properly grounded using approved grounding clamps and grounding cables or if applicable a
grounding switch. If it’s not grounded it’s not dead.
Note: Grounds may be removed from the remote terminal(s) if a dangerous potential will develop at the
work site should a fault develop in another cable. Grounds may also be removed for terminator and/or
cable replacement and for testing purposes.
*Note: Switching and tagging rules shall be followed when deenergizing equipment (refer to switching and
grounding sections)
3.26
Padmount/submersible transformers may be fed from two directions. For this reason all
transformers shall be considered energized until tests are made and grounds installed.
3.27
After being disconnected from the power source, a cable may retain a capacitive charge. Discharge
and ground before making physical contact.
3.28
Any cable or equipment under clearance shall be tested for voltage and then grounded at the first
possible grounding point before work is attempted.
3.29
All cable or equipment not tested and grounded shall be worked with adequate protective devices
as though it was energized.
3.30
Due to loop characteristics of underground circuits, both top and bottom portions of primary
switches shall be considered energized, even in open position until tested and grounded.
3.31
Always check to make sure that all grounds have been removed before equipment, which has been
grounded, is put back into service.