- Work in Excess of 600 Volts -
7.0 WORK IN EXCESS OF 600 VOLTS
Qualified and competent electrical workers are required to perform a variety of tasks with and
around higher voltage electricity, electrical equipment, and apparatus. The nature of such work necessitates an
understanding of applicable safety policies and rules.
Many electrical hazards and work practices are the
same regardless of the voltage involved.
However, due to the nature of high voltage work, there are many
hazards and work practices
that are specifically related to high voltage. Refer to chapter 2 of this document
for more details.
7.1 RESPONSIBILITIES FOR SAFETY
This section provides safety guidelines and
requirements for carrying out assigned job tasks. It
is essential that each employee exercise sound judgment to
perform assigned tasks safely.
Safety is the responsibility of each employee.
greatest responsibility for a worker's safety lies directly with the worker. This means that all
responsible for performing their work in a manner that does not endanger
themselves, their co-workers, or
others in the area and for complying with safety rules and
requirements. Workers should not rely solely on the
care exercised by another for their
protection. Workers are encouraged to contribute to the safety program and
bring to the
attention of their supervisors or safety representative any condition they believe is unsafe.
Other safety responsibilities of workers include the following:
1. The worker should examine the work area
for existing hazards and proceed in a safe
2. When seen in a dangerous situation, fellow workers
should be warned in such a manner as
to avoid confusing, startling, or suddenly alarming them.
3. Before climbing poles, ladders, or other such structures or before working on scaffolds,
workers shall make a careful inspection to determine whether the structures are safe and
supported. Workers should not carry anything in their hands while ascending or
descending ladders. Small
objects or tools may be carried in pockets or pouches. Larger
objects, however, should be raised or lowered by
use of hand lines or ropes and blocks.
Others working nearby or below should remain out of line of the work
area in case anything
should accidentally be dropped.
4. It is the responsibility of each worker to attend safety meetings. Workers should also make a
learning safety information made available to them that will help them perform
their work more safely.
5. The worker shall report to the supervisor any personal injury as defined by the
soon as possible.
6. The worker should exercise care and good judgment when lifting heavy
help if the object is too heavy or awkward for one person to handle.
Supervisors are responsible for knowing and implementing applicable safety policies and
directives and taking action as required to provide for the safety of the personnel and operations
supervise. This includes; taking positive action to determine and reduce, as necessary, the
with their operations; instructing employees in safe work methods and
associated safety requirements; allowing
only those employees that are qualified for the work to
perform the work; and ensuring that employees perform
their work safely.
Supervisors shall be responsible for the safety of all employees under their supervision. They
shall enforce the rules that apply to the hazards involved.
Supervisors shall make certain that each new or
transferred employee is instructed in the safe
practices pertaining to his or her work.
shall ensure that the appropriate employees receive instruction in appropriate
emergency techniques, such as
CPR, first aid, pole top, and confined space rescue, warranted
by the employee's duties.
Other duties of
supervisors include the following:
1. Provide instructions on safe practices for the crew and see that they are followed.
2. Periodically examine supervised employees on their knowledge of the safety rules and
3. Not allow a worker to perform any task that cannot be performed safely or for which the
worker is not qualified.
4. Report every injury in the established manner prescribed for the facility.
5. Be responsible for the care and proper use of all protective devices.
6. Be responsible for proper
posting of hazardous work areas as a safeguard to those
supervised. Under no circumstances shall the supervisor
allow work to continue if safety
precautions are ignored.
7. Designate a qualified worker to be in charge of work during the supervisor's
supervisor should not leave the job while dangerous work is in progress.
8. Coach and
direct employees who are working near exposed, energized wires, equipment, or
along with employees, the appropriate PPE when establishing safety related work
7.2.1 EMPLOYEE TRAINING
Employees shall be trained in and familiar with the
safety-related work practices, safety
procedures, and other safety requirements in this section that pertain to
their respective job
Employees shall also be trained in and familiar with any other safety
applicable emergency procedures that are not specifically addressed in this section but
related to their work and necessary for their safety.
7.2.2 QUALIFIED EMPLOYEE TRAINING
Qualified employees shall be trained and competent in:
1. The skills and techniques necessary to
distinguish exposed live parts from other parts of
2. The skills and techniques
necessary to determine the nominal voltage of exposed live parts.
3. The skills and techniques necessary to
determine the minimum approach distances
corresponding to the voltages to which they are exposed.
4. The proper use of the special precautionary techniques, personal protective equipment,
insulating and shielding materials, and insulated tools for working on or near exposed
energized parts of
Training may consist of a combination of classroom and on-the-job type.
The employee in charge shall conduct a job briefing with the employees involved before the
start of each job. The job briefing will at least cover the following subjects: hazards associated
job, work instructions involved, special precautions, energy source controls, and
personal protective equipment
If the work or operations to be performed during the work day are repetitive and similar, at
one job briefing shall be conducted before the start of the first job of each day or shift. Additional
job briefings shall be held if significant changes, which might affect the safety of the employees,
during the course of the work.
A brief discussion is satisfactory if the work involved is routine and if
the employee, by virtue of
training and experience, can reasonably be expected to recognize and avoid the
involved in the job. A more extensive discussion shall be conducted if the work is complicated or
extremely hazardous, or the employee cannot be expected to recognize and avoid the hazards
involved in the job.
An employee working alone need not conduct a job briefing. However, the employee shall
ensure that the tasks to
be performed are planned as if a briefing were required.
7.4 PERSONAL PROTECTIVE EQUIPMENT AND PROTECTIVE CLOTHING
Employees shall wear appropriate personal
protective equipment (PPE) and protective clothing
(see Section 7.4.8) to protect them from hazards of
high-voltage apparatus. Employees
authorized or required to work on high-voltage systems shall be completely
familiar with the
PPE and protective clothing they need for adequate protection while working on such systems.
(Refer to Appendix C for suggested types of PPE and protective clothing.) (See Figure 7-1)
Figure 7-1. Appropriate personal protective equipment and protective clothing shall be worn by electrical
workers to protect them from electrical hazards.
Employees should wear shoes or boots that comply with the requirements of ANSI Z41. No
parts shall be present in the sole or heel of the shoes where nonconductive shoes are
Workers should wear approved hardhats when working aboveground on poles, structures, or
buildings or in trees.
Workers shall wear hardhats when working on the ground near poles, structures,
trees in which work is being done. Workers shall wear hardhats when visiting or observing in
areas where overhead work is being done.
Figure 7-1. Appropriate personal protective equipment and
protective clothing shall be
worn by electrical workers to protect them from electrical hazards.
7.4.3 EYE PROTECTORS
Whenever eyes are in danger of being injured, workers shall wear safety
goggles or other eye
protectors meeting ANSI standards. When the work being performed dictates, workers should
wear nonmetallic and nonconductive eye protection. Appropriate PPE is needed to protect
workers from arc flash
7.4.5 METAL FASTENERS
Workers shall not wear articles such as loose chains, keys, watches, or rings if such articles
increase the hazards associated with inadvertent contact with energized parts or can become
caught under or snagged while climbing off or on structures, equipment or vehicles.
7.4.6 WORK GLOVES
When insulated gloves suitable for high-voltage are not required, otherwise suitable work gloves
should be worn
while handling materials and equipment to prevent the possibility of slivers, cuts,
and skin irritation.
7.4.7 WORK CLOTHES
Work clothes should be made of natural materials, such as cotton or wool, or fire
materials and should have full length sleeves. Sleeves should be rolled down for greatest
7.4.8 FIRE-RESISTANT (FR) CLOTHING
FR materials, such as flame-retardant treated cotton,
meta-aramid, para-aramid, and polybenzimidazole
(PBI) fibers provide thermal protection. These materials can
ignite but will not
continue to burn after the ignition source is removed. FR fabrics can reduce burn injuries
an arc flash blends, para-aramid adds strength to a fabric to prevent the fabric from breaking
due to the blast shock wave and high thermal energy of the arc.
All fire resistant fabrics comply with 29 CFR 1910.269(1)(6)(iii). Untreated cotton and
comply if the fabric will not ignite and continue to burn under the conditions to which the
could be exposed. ASTM F1506-94 and 2 new ASTM provisional standards, outline
the testing procedures to
determine how various fabrics react in the presence of an electric arc
on an instrumented manikin or panel. The
new ASTM provisional standards provide testing
procedures that expose untreated and fire resistant fabrics to
electric arcs. F1506-94 provides
testing procedures that expose these same fabrics to a vertical flame test.
Also see NFPA 70E,
110.7(A) for details on flash hazard analysis.
188.8.131.52 ELECTRIC ARC HAZARDS
Electric shock is a widely recognized hazard and involves current flow through or on the body.
electric arcs are not as well recognized. There is no contact required and the burns
can be severe if the
clothing ignites or melts. The hazards to which the employee is exposed
also include the clothing breaking open
due to the arc pressure blast, the heat from the electric
arc and subsequent secondary fires or explosions.
The extent of the employee's injury is dependent on the length of the arc gap, available fault
duration of the arc, the distance of the employee from the arc, percentage of the body
burned, the employees
age, medical condition, and number of layers of the clothing system.
The proper clothing system will minimize
or reduce the burn injury.
184.108.40.206 TYPES OF FIRE RESISTANT FABRICS
Chemically dependent fire
resistant fabrics are treated with flame retardant chemicals added to
the fiber or treatments applied to the
fabric. These treatments are activated by heat and produce
gases that smother the flame. Typically, these
fabrics have a definite life as defined by the
manufacturer. This is usually defined by the number of home or
commercial washings the
garment is exposed.
Inherently fire resistant fabrics, by their composition, do
not burn in air. The fire resistance of
this fabric is not affected by washing.
220.127.116.11 CLOTHING SYSTEMS
All clothing worn by affected workers should be considered part of the employees protective
This includes rainwear, cold weather wear and underclothing. Protective
clothing should provide a good
functional fit to increase the protection and comfort of the
clothing. When required, protection can be
increased by wearing single or multiple layers of
flame-resistant outer garments over nonmelting clothing.
Sleeves and shirts should be fully
buttoned and appropriate neck, head, and hand coverings provided.
7.4.9 RUBBER GLOVES
The following requirements apply:
1. Rubber gloves shall be of appropriate
voltage rating for the work being performed. All rubber
gloves shall meet the standards set forth by ANSI/ASTM.
2. Rubber gloves issued for service shall be tested at appropriate voltage levels at intervals not
3. Leather glove protectors shall be worn over rubber gloves except where leather protectors
not required by 29 CFR 1910.137 or the appropriate ASTM standard.
4. Rubber gloves should be carried cuff
down in a bag, box, or container that is designed for
this purpose. Rubber gloves may be kept inside of leather
5. Rubber gloves shall be visually inspected and field air-tested before use each day and at
other times if there is cause to suspect damage.
6. Rubber gloves should be uniquely identified (i.e., serial number or other marking). The
results of dielectric tests should be documented.
7. Rubber gloves shall be wiped clean of any oil, grease,
or other damaging substances as
soon as possible.
7.4.10 RUBBER LINE HOSE, HOODS, COVERS, SLEEVES, AND BLANKETS
Linemen's rubber insulating sleeves
are worn to provide protection from electric shock and burn
to the arm and shoulder areas. They are available
in several different thicknesses, lengths, and
designs, depending on the maximum voltage they are designed to
Insulating line hose (flexible hose) is used as an insulating cover for electric
protect against accidental contacts. A lengthwise slit with overlapping sides permits the hose to
be placed on conductors easily. It is available in various diameters, lengths, and compositions.
covers are used in conjunction with line hose to cover an insulator and the conductor
attached to it for
protection against accidental contact.
Rubber insulating blankets are molded sheets of insulating rubber or
usually square or rectangular in shape, designed to cover energized electrical equipment
prevent direct accidental contact by electrical workers.
7.4.11 LIVE LINE TOOLS
periodic inspection shall be made of equipment used for handling or testing energized
lines or equipment. Such
tools shall be examined before each use to make certain they are in
shall be given to preserving the surfaces of wooden and fiberglass tools
used around electrical equipment,
including ladders, pike poles, switch sticks, live-line tools, and
insulating platforms. Only colorless varnish
or other appropriate transparent insulating
preservative shall be used.
Insulated tools shall be stored in a dry location. Suitable containers or racks shall be provided to
protect the tools from mechanical damage and warping.
7.4.12 STOREROOM STORAGE
Since heat, light, oil, and distortion are natural enemies of rubber, rubber protective equipment
should be guarded from these as much as possible. Rubber equipment shall not be stored near
boiler rooms, steam pipes, or radiators and should be protected from exposure to direct
Gloves should be stored in their natural shape in the leather protector. Keep sleeves flat with
left in. Blankets should be stored flat, hung on pegs by the eyelet or rolled up. Line
hose should be stored in
its natural shape.
7.4.13 TRUCK STORAGE
The storing of rubber protective equipment on the truck
should be planned. If possible, separate
compartments should be provided for each class of equipment, and each compartment should
be of sufficient size
to allow the articles to lie in a natural position. Rubber gloves should be
stored in glove bags and hung up. If stored in tool bags or inside boxes, nothing should be piled
on top to cause distortion. Gloves should not be stored near vehicle heaters.
Sleeves should be stored flat with inserts rolled up lengthwise, or placed in a tube shaped bag.
Nothing should be placed on top of sleeves or stored near vehicle heaters.
7.4.14 PLACING OF INSULATING
GOODS ON CONDUCTORS
When workers are about to begin work that requires the use of rubber goods, they should
or raise the bucket to a position just below the first line of conductors. When climbing they
then determine their working position and what lines and other conductors should be
covered. They should then
request the required rubber goods. Before proceeding further, the
workers shall put on the rubber gloves and
leather protectors and make certain that they are in
good order. Rubber goods shall be raised in a secure
As the workers ascend to their working position, they shall cover all conductors which provide a
This should be done from below whenever possible. At no time shall workers pass
through energized equipment before it is covered with rubber goods (line guards). All
conductors and grounds
adjacent to working space shall be considered, including those near
any possible change of position that may be
necessary. When line hose is applied to vertical or
sagging wires, it should be fastened to the line to prevent
its slipping from position. When
blankets are used for covering items such as dead ends, potheads, secondary
transformers, they should be secured by wooden or plastic clamp pins or tie thongs. After the
protective equipment has been placed, care should be taken to prevent damage to the rubber
from tie wires,
spurs, or other objects.
7.4.15 REMOVING INSULATING GOODS FROM CONDUCTORS
When the job is completed,
the protectors should be removed in the reverse order of
installation. Remote conductors are removed first and
the wires nearest the workers last. After
being detached, the equipment should immediately be lowered to the
7.4.16 CLEANING AND INSPECTING
After the rubber goods have been lowered to the ground, they should be cleaned and visually
inspected before being placed in the carrier compartments of the truck.
7.5 PROTECTIVE GROUNDING OF LINES
Grounding is the most effective way of protecting electrical workers from electric shock.
why it is important to ensure that all deenergized lines and equipment are grounded.
Blankets should be rolled up and placed in canisters or protective canvas holders. Do not fold,
hold together with tape, pile materials on top of, or store blankets near vehicle heaters.
provides information concerning protection for workers repairing, servicing, or
working on high-voltage power
Figure 7-2. Equipotential grounding is the most effective way of protecting employees who are working on
high-voltage systems and equipment.
18.104.22.168 REDUCE THE POTENTIAL VOLTAGE DIFFERENCES ACROSS THE WORKER
The primary function of personal protective grounds is to provide maximum safety for personnel
while they are
working on deenergized lines or equipment. This will be accomplished by making
provisions that will reduce the
potential voltage differences at the work site (voltage differences
across the worker) to a safe value in the
event that line or equipment being worked on is
accidentally reenergized, voltages induced from other energized
lines, an energized line falls on
the line being worked, or there is a lightning strike near the line being
The personal protective grounds should provide a low-impedance path to ground to ensure
operation of the circuit protective devices.
Certain methods and steps should be exercised when placing grounds and loads to protect
workers from high-voltage hazards.
22.214.171.124 DEENERGIZED LINES
When an energized line or equipment in
excess of 600 V is removed from service to be worked
on, it shall be treated as energized until it is
deenergized, tagged, locked if necessary, tested,
Figure 7-2. Equipotential grounding is the most effective way of protecting employees
who are working on
high-voltage systems and equipment.
126.96.36.199 NEW CONSTRUCTION OR DISMANTLING OF FACILITIES
If isolating devices are not in place and
energization is impossible from any source, single-phase
grounding is appropriate, acceptable, and safe. If
energization is possible by the closure
of a jumper or isolating device, shorts and grounds shall be used
unless conductor handling
activity makes this impractical or impossible because of line design or construction
188.8.131.52 MINIMUM APPROACH DISTANCE FROM UNGROUNDED CONDUCTORS
The minimum approach distances
in Section 184.108.40.206 shall be maintained from ungrounded
conductors at the work location. The ground may be
omitted if the making of the ground is
impractical or the resulting conditions are more hazardous than working
on the lines or
equipment without grounding. However, all work shall be done as if the line or equipment were
220.127.116.11 VISIBLE THREE-PHASE SHORT AND GROUND REQUIRED
Visible three-phase short circuiting may be accomplished through conductive parts such as guy
unpainted metal tower members, but shall not be effected through a grounding mat or
other concealed conductors.
18.104.22.168 GROUND CIRCUIT
No power disconnect switch, power circuit breaker, transformer, wave trap, or fuse
shall be part
of the protective grounding circuit.
Table 7-2. AC live-line work minimum approach
Note 1: These distances take into consideration the highest switching surge an employee will be exposed
tto on any system with air as the insulating medium and the maximum voltage shown.
Note 2: The clear live
line tool distances shall equal or exceed the values for the indicated voltage ranges.
Note 3: See 29 CFR
1910.269, Appendix B for information on how the minimum approach distances were
7.5.3 GROUNDING EQUIPMENT
ASTM Committee F-18, Electrical Protective Equipment for Workers, has
published a consensus standard for protective grounds, ASTM Designation: F-855. This
consensus standard may be used by all Federal agencies for procurement purposes.
Therefore, grounding cables,
clamps, and ferrules purchased should meet all the requirements
of ASTM Designation: F-855. Aluminum cables
shall not be used for personal grounds.
The grounding of high-voltage lines and equipment will provide workers
protection from electric shock if grounds are sized, selected, and installed properly.
Grounding cables shall be available for use when work is being done on deenergized
22.214.171.124 APPROVED CAPACITY
Grounding cables shall accommodate the maximum
fault current to which the cable or
equipment might be subjected.
126.96.36.199 GROUNDING CABLES AND HARDWARE
Personal protective grounding cables consist of appropriate
lengths of suitable copper
grounding cable, with electrically and mechanically compatible ferrules and clamps
at each end.
In addition, appropriate hot sticks are required for installing and removing the conductor-end
clamps to the conductors. Hot sticks are required for attaching ground-end clamps if the
grounded system and
the worker are at different potentials. Cluster bars provide a low resistance
means of connecting the
ground-end clamps. Each of these components will be
discussed in the following subsections.
Most of the grounding cables in use today (and available for purchase) are actually
another purpose-principally as welding cable. These extra-flexible copper
cables with jackets are manufactured
according to appropriate ASTM standards for both cables
and jackets, and can be expected to perform
satisfactorily as grounding cables.
There are several classes of flexible cable
with various stranding in the sizes normally used for
Welding cables are nominally insulated at 600 volts. When used
as grounding cable, the
insulation or jacket serves primarily for mechanical protection of the conductor. The
elastomer or thermoplastic jackets are manufactured, applied, and tested according to ASTM
standards. Black, red, and yellow jackets are usually neoprene rubber compounds, while clear
ultraviolet-inhibited polyvinyl chloride (PVC). All jackets should have the AWG size
stamped or printed
repeatedly along the length of the cable. The clear jacket allows easy visual
inspection of the conductor for strand breakage, but becomes stiff and hard to handle at low
temperatures. The clear jacket will split or shatter at very low temperatures.
Ferrules should be threaded-stud copper base compression type. Ferrules should have
compound vent hole at the bottom of the cable so that employees can visually check that the
is fully inserted into the ferrule. Compound should be used with crimped ferrules. The
ferrules should be
crimped with the ferrule manufacturer's recommended die. The press shall
have enough pressure to completely
close the die. The area covering the inserted cable jacket
should not be compressed. Heat shrink or springs
should be installed over a portion of the
ferrule to minimize strand breakage caused by bending. In all cases,
recommendations should be followed.
188.8.131.52.4 HANDLING OF GROUNDING CABLE
Personal protective grounds are usually handled and lifted by the cable. However, continuous
breaks the conductor strands beneath the jacket. Therefore, employees
should minimize the use of sharp bends in the cable.
184.108.40.206.5 SIZE OF GROUNDING CABLE
The size of the grounding cable must be selected to handle the maximum calculated fault
current of the power system or specific portion thereof. The minimum size that shall be used for
grounding cables is #2 AWG flexible copper. In larger substations, the maximum available fault
current may require larger cables. If larger cables are not available, parallel cables (with the
appropriate derating factor) may be used.
Most manufacturers and suppliers of grounding cables publish
tables to assist the user in
selecting the proper cable size for a given fault current. These tables show the
current capability for several sizes of copper grounding cables.
220.127.116.11.6 GROUNDING CABLE
Excessive cable lengths should be avoided. Therefore, slack in the installed cables should be
minimal to reduce possible injury to workers. Resistance in the cable increases with cable
excessive length could exceed the tolerable voltage drop across the body. Longer
than necessary cables also
tend to twist or coil, which reduces the effectiveness of the cable.
18.104.22.168.7 GROUNDING CLAMPS
Grounding clamps are normally made of copper or aluminum alloys; sized to meet or exceed
the current-carrying capacity of the cable; and designed to provide a strong mechanical
connection to the
conductor, metal structure, or ground wire/rod.
22.214.171.124.7.1 CLAMP TYPES
Clamps are furnished in, but
not limited to, three types according to their function and methods
1. Type I clamps,
for installation on deenergized conductors, are equipped with eyes for
installation with removable hot sticks.
2. Type III clamps, for installation on permanently grounded conductor or metal structures,
have T-handles, eyes, and/or square-or hexagon-head screws.
3. Other types of special clamps are designed
for specific applications, such as cluster
grounds, underground equipment grounding, and so on.
126.96.36.199.7.2 CLAMP JAWS
Bus clamps should be furnished with smooth jaws for installation on copper,
silverplated bus work without marring the surface. Conductor or metal structure clamps should
be furnished with serrations or cross-hatching designed to abrade or bite through corrosion
surfaces of the conductor or the metal structure being clamped. Several styles of
conductor and ground-end
clamps have jaws that can be replaced when the serrations have
worn. Self-cleaning jaws are recommended for
conductor-end clamps used on aluminum or
aluminum conductor steel reinforced (ACSR) conductors. Several styles
of ground-end clamps
are designed with a cup-point set screw which should be tightened with a wrench (after the
serrated jaws have been securely tightened) to break through paint, rust, galvanized coating, or
the surface that is to be clamped.
A typical grounding cable for transmission line work used by line crews
consists of a 2/0 AWG
copper cable with an insulating jacket, terminated with an all-angle, self-cleaning
conductor clamp at one end, and a flat-faced clamp with a set screw at the other end for
to a tower leg or ground wire/rod.
188.8.131.52.8 GROUNDING CLUSTER BARS
When climbing wood-pole
structures, workers may use a grounding cluster bar to connect the
phase cables to the pole ground wire, if the
ground wire has sufficient capacity to carry the fault
current. Cluster bars must have an attached bonding
lead. If there is no pole ground wire, the
cluster bar for each pole is connected to a common driven or
screw-in ground rod with a
grounding cable (or cables). In substation grounding, a copper bar is sometimes used
connect the three-phase cables and a fourth cable to a riser from the station ground mat. When
personal grounds on wood structures from a bucket, the ground cables may be
connected between the overhead
ground wire (OGW), and the phases without the use of cluster
bars provided that an electrical bond of
sufficient current carrying capacity exists between the
OGW and the structure ground.
184.108.40.206.9 TEMPORARY GROUND RODS
Some typical examples of temporary ground rods used for grounding
ungrounded structures or
mobile equipment, or during conductor splicing operations, are either:
minimum ⅝-inch diameter bronze, copper, or copper-weld rod at least 6 feet long, driven
to a depth of at least
5 feet; or
2. A 6-foot, screw-type ground rod, consisting of a minimum ⅝-inch diameter copper-weld shaft
with a bronze auger bit and bronze T-handle, screwed to a depth of at least 5 feet
(preferred). The T-handle
must be tightly connected to the rod.
If a temporary rod cannot be driven or screwed to a depth of 5 feet,
additional rod(s) should be
driven or screwed so that a total of at least 5 feet of rod is buried. These rods
shall be bonded
together with grounding cables prior to installing phase grounds. The rods should be placed 6 to
apart; however, the 10-foot clearance from the rods should be maintained. OGWs may be
used at any time to bond
the conductors provided that these wires are electrically bonded to the
structure ground, either permanently or
by personal grounds.
Groundsmen should stay clear (at least 10 feet where feasible) of items such as down
ground rods, maintenance vehicles, and structure legs or ground wires while they are bonded to
protective grounds which are in place. When it is absolutely necessary to work on or near these
employees should use bonded conductive or insulated platforms, or approved
insulated shoes to minimize the
hazard from step and touch potentials.
7.5.4 TESTING BEFORE INSTALLING GROUNDS
Before grounds are installed, the deenergized line or equipment shall be tested for voltage.
Appropriate testers for the nominal voltage involved (audio or visual) should be used. They shall
be tested immediately before and after use to verify that they are in good working condition.
7.5.5 ATTACHING AND REMOVING GROUNDS
Employees attaching and removing grounds shall comply with the
1. Grounding equipment should be visually inspected and all mechanical connections checked
for tightness before each use.
2. The surface to which the ground is to be attached should be clean before
clamp is installed or a self-cleaning clamp shall be used.
3. No ground shall be removed
until all personnel are clear of the temporary grounded lines or
equipment. When the grounding set is removed,
it shall be disconnected from the line or
equipment end first with an approved hot-line tool and moved to a
point clear of energized
conductors before the ground end is disconnected.
7.5.6 GROUNDING METHODS AND
LOCATION OF GROUNDS IN ORDER OF PREFERENCE
Employees installing grounds shall install them using the
information given in the following
220.127.116.11 WORK LOCATION
Grounds should be installed at the work location with all grounded parts of different potential
bonded together (on wood poles, all down guys, overhead ground wire, neutral conductor, and
pole ground). The cluster bar assembly should be installed below the working area and jumper
to the ground point or the neutral conductor and the phase conductor, a method of grounding
termed "equipotential" grounding. It provides the greatest margin of safety for the lineworker by
everything at equal potential, eliminating the possibility of the lineworker getting in series
18.104.22.168 MULTIPLE WORK LOCATIONS AND SINGLE-PHASE GROUNDING AT WORK LOCATION
If work is to be
performed at more than one place in a line section, the line section shall be
grounded at one location and the conductor be grounded at each work location to reduce the
potential voltage difference across the work site.
22.214.171.124 OTHER LOCATIONS
Grounds shall be placed
at the work location or at each side of the work location and as close
as practical to it.
Grounds may be temporarily removed when necessary for testing. Each employee shall use
insulating equipment and be isolated from any hazard involved. Additional measures may be
necessary to protect
each exposed employee in case previously grounded lines or equipment
In cases where ground rods or pole grounds are used for personal protective grounding,
personnel working on the ground shall either maintain a safe distance from such equipment or
appropriate equipment designed to prevent touch-and-step potential hazards. The term
"touch potential hazard"
refers to the difference in voltage measured between the grounding
equipment and a worker in contact with the
grounding equipment at the time it is accidentally
energized. The term "step potential hazard" refers to the
difference in voltage measured
between each foot of the worker standing or walking in an electrical field
created by high voltage
brought to earth.
7.6 INSTALLING OR REMOVING CONDUCTORS
Employees installing or removing conductors should follow certain
guidelines to ensure safety.
7.6.1 WORKING ON ENERGIZED LINE OR EQUIPMENT
Employees working on energized lines or equipment should comply with the following:
1. Work on electrical
equipment and circuits other than electrical utility lines and equipment,
operating a 50 V or more ground, should be worked on following the guidelines of Section 2
of the handbook.
2. Line or equipment carrying an ac voltage in excess of 600 V phase-to-phase should be
worked on with rubber gloves or live line tools. All other necessary protective devices such
as line hose,
hoods, covers, sleeves, and rubber blankets should be used. (See Section
3. Energized line should be worked on from below whenever possible. When working
energized line or equipment carrying 600 V or more to ground, there shall be two qualified
workers performing the work (see Section 2.1.2). Work shall not be performed on energized
lines or equipment during rain, snow, sleet, fog, and other damp conditions, except in
extreme emergencies if in the opinion of supervision and line crew it can be done safely.
4. While working on the same pole, workers shall not work simultaneously on wires that have a
5. Rubber gloves of appropriate voltage rating shall be worn when working within reach of a
fellow employee who is working on or within reach of wires or equipment carrying voltage in
excess of 600 V.
6. Insulated tongs or disconnect sticks shall be used to open or close plugs or fuses or to
7.6.2 STRINGING OR REMOVING DEENERGIZED CONDUCTORS
Employees stringing or removing deenergized conductors
should follow certain safe work
practices. Consideration should be given to the following:
1. When it is necessary to conduct any work on poles or structures carrying more than one
circuit and where there is not safe working clearance between circuits, the conductors not
being worked on shall be either:
a. Untied and separated with proper clearance from the pole or structure,
b. Deenergized and grounded, or
c. Covered with the necessary protective devices.
2. Prior to stringing
operations, a job briefing shall be held setting forth the plan of operation
and specifying the type of
equipment to be used, grounding devices to be used and
instructions to be followed, crossover methods to be
employed, and clearance authorization
3. Where there is a possibility that the conductor will accidentally contact an energized circuit
or receive a dangerous induced voltage buildup, to protect the employee from the hazards
of the conductor, the
conductor being installed or removed shall be grounded or provisions
made to insulate or isolate the employee.
4. If the existing line is deenergized, proper clearance authorization should be secured and the
on both sides of the crossover, or the line being strung or removed should be
considered and worked on as
5. When workers cross over energized conductors, rope nets or guard structures shall be
installed unless provisions are made to isolate or insulate the workers or the energized
practical, the automatic reclosing feature of the circuit-interrupting device
should be made inoperative. In
addition, the line being strung should be grounded on either
side of the crossover or considered and worked on
6. Conductors being strung or removed should be kept under positive control by the use of
adequate tension reels, guard structures, tielines, or other means to prevent accidental
contact with energized
7. Guard structure members should be sound, of adequate dimension and strength, and
8. Catch-off anchors, rigging, and hoists should be of ample capacity to prevent loss
9. The manufacturer's load rating should not be exceeded for stringing lines, pulling lines, sock
connections, and all load-bearing hardware and accessories.
10. Pulling lines and accessories should be inspected regularly and replaced or repaired when
damaged or when their dependability is doubtful.
11. Conductor grips should not be used on wire rope unless
designed for this application.
12. While the conductor or pulling line is being pulled (in motion), workers
should not be
permitted directly under overhead operations, nor should any employee be permitted on the
13. A transmission clipping crew should have a minimum of two structures clipped between the
crew and the conductor being sagged. When working on conductors, clipping crews should
install grounds at the
work location. The grounds should remain intact until the conductors
are clipped in, except on dead-end
14. Except during emergency restoration activities, work from structures should be discontinued
when adverse weather (such as high wind or ice on structures) makes the work hazardous.
15. Stringing and clipping operations should be discontinued during an electrical storm in the
16. Reel-handling equipment, including pulling and braking machines, should have ample
capacity, operate smoothly, and be leveled and aligned in accordance with the
17. Reliable means of communication between the reel tender and pulling rig operator should
18. Each pull should be snubbed or dead-ended at both ends before subsequent pulls.
7.6.3 STRINGING ADJACENT TO ENERGIZED LINES
Employees stringing adjacent to energized lines should follow
certain safe work practices.
Consideration should be given to the following:
1. When performing work
from structures, clipping crews and all others working on conductors,
subconductors, or overhead grounding
conductors should be protected by individual
grounds installed at every work location.
2. When workers are stringing adjacent to energized lines, the tension-stringing method or
other methods that prevent unintentional contact between the lines being pulled and any
worker should be used.
3. All pulling and tensioning equipment should be effectively grounded.
4. A ground should be installed between the tensioning reel setup and the first structure to
each bare conductor, subconductor, and overhead grounding conductor during
stringing across or adjacent to
5. During stringing operations, each bare conductor, subconductor, and overhead grounding
conductor should be grounded at the first tower adjacent to both the tensioning and pulling
setup and at
appropriate intervals. The grounds should be left in place until conductor
installation is completed. Except
for moving-type grounds, the grounds should be placed
and removed with a hot stick.
subconductors, and overhead grounding conductors should be grounded at all
dead-end or catch-off points.
7. A ground should be located at each side and within 10 ft. of working areas where
subconductors, or overhead grounding conductors are being spliced at ground
level. The two ends to be spliced
should be bonded to each other. It is recommended that
splicing be carried out on either an insulated platform
or on a conductive metallic grounding
mat bonded to both grounds. When a grounding mat is used, it should be
roped off and an
insulated walkway provided for access to the mat.
7.7 SPECIAL TOOLS
shall be familiar with special tools that are used for climbing, such as climber gaffs,
climber straps, and
body belts shall properly store and maintain such equipment.
7.7.1 LINEWORKERS’ CLIMBING TOOLS
Employees should apply the following:
1. All climbers should be inspected frequently by the worker using
2. Climber gaffs should be kept sharp.
3. A climber shall not be used when its gaff becomes
shorter than 1-1/4 in. inside measurement.
4. Climber straps that are worn or otherwise defective shall be
7.7.2 BODY BELTS AND SAFETY STRAPS
Employees using body belts and safety straps (work positioning equipment) should apply the
1. All body belts and safety straps shall be inspected before each use by the employee who uses
2. Workers shall use their body belts and safety straps when doing any work involving danger of
3. Body belts and safety straps should not be stored with unguarded sharp tools or devices.
Figure 7-3. Employees using special tools for climbing and for servicing high voltage systems shall be trained
on how to use such tools and equipment.
4. Heat, sharp bends, and overstressing of body belts and safety
straps should be avoided as
they are injurious to leather. Wet leather should be dried slowly at moderate
7.7.3 TOOL BAG AND EQUIPMENT
Tools, small equipment, and materials should be raised
and lowered in a tool bag. The tool bag
should be inspected before use to see that it contains no broken glass
or other material on
which the employee could cut his or her hand or rubber gloves. Tool bags should not have
metal in their construction.
7.7.4 TAPES AND RULERS
Workers should not use metal measuring
tapes or tapes having metal strands woven into the
fabric, brass bound rules, or metal scales when working near
electrical equipment or conductors
7.7.5 SPOON AND SHOVELS
Tools of this type, especially those
having long wooden handles, shall not be used when the
handles are cracked, split, or broken.
7-3. Employees using special tools for climbing and for servicing high voltage
systems shall be trained on how
to use such tools and equipment.
7.7.6 PIKE POLES
Pike poles shall comply with the following:
1. Cracked, broken, or slivered
pike poles should not be used;
2. Pike poles should not be thrown; and
3. When not in use and loaded
on the truck, the points should be protected so that they will not
7.7.7 HAND AXES AND
Hand axes and sharp tools shall comply with the following:
1. Hand axes should not be
used on overhead work; and
2. When not in use, sharp tools should be protected by the suitable guards or
7.7.8 HANDLINES AND TAGLINES
Use high quality, nonconductive hand lines and taglines. Keep them stored
in a clean, dry
location and protected from damage and contamination. Wear clean gloves when handling
lines and taglines to avoid contaminating the rope. Remove wet, dirty, or damaged ropes
7.8 TREE TRIMMING
Equipment used to trim trees shall be maintained in approved and proper working condition
aid tree trimmers and protect them from hazards.
7.8.1 CARE AND USE OF TOOLS
Tools shall be
cared for using the following methods:
1. The handles of all tree-trimming tools shall be kept well dressed
2. When trimming trees near live conductors, the employee shall not work with wet tools or
ropes. Such equipment should be protected during rain showers.
3. A tree-trimming saw shall be protected by being put into its scabbard when it is not in use.
ropes shall be inspected frequently for cuts and wear.
The following shall be applied for climbing:
1. An employee should use a ladder to climb a tree, unless
the employee is properly equipped
and trained for tree climbing.
2. Climber gaffs and straps shall be designed for tree climbing. The safety strap shall be
to withstand contact with saws and other sharp objects. Workers in trees shall
be tied off.
7.9 SERIES STREET-LIGHTING CIRCUITS AND APPARATUS
Lighting circuits and apparatus used
for series street-lighting should comply with the following:
1. Rubber gloves or any other necessary
protective equipment should be used when working
on a series street-lighting circuit, unless the circuit is
electrically isolated and grounded at
the work location. Unless properly tagged and isolated, series street
lighting circuits should
be considered as being energized.
2. The opening of a time clock, a
photoelectric relay, or remote control overcurrent control
equipment shall not be considered as isolation
points that provide a safe work condition
while employees work on series lighting circuits.
3. The use
of series lighting circuits is discouraged.
Underground work requires a means of
safe entrance and exit from the workspace. Employees
should follow the guidance given in the following
subsections to ensure safety in entering and
leaving such work spaces.
7.10.1 WORKING IN MANHOLES, UTILITY TUNNELS, AND VAULTS
Manholes, utility tunnels, and vaults may be
considered confined spaces and shall comply with
29 CFR 1910.146,1910.269(e) and (t), and 1926.956. The
following may apply to employees
working in manholes, utility tunnels, and vaults:
1. Employees who
enter manholes shall be trained in the hazards of the confined spaces,
confined space entry procedures, and
confined space emergency and rescue procedures.
2. When opening a manhole, employees shall completely remove the manhole cover from the
opening. Manhole covers should be removed before the cable is rodded or installed and
3. Open manholes shall be barricaded and protected by flags or guards as required. All open
manholes shall be protected as required by 29 CFR 1910.269(e).
4. Before the pit is entered, it shall be
tested for oxygen content and the flammable-gas
explosive limit. Workers shall not smoke or use an open flame
while tests for an explosive
mixture of gas are being made.
5. If the oxygen level is less than 19.5 percent or greater than 21 percent, the pit shall be
and retested before any work begins.
6. If the flammable-gas content is more than 10% of the lower
explosive limit, the pit shall be
ventilated and retested before any work begins. When testing indicates that a
contains either a mixture of explosive gas and air richer than safe working limits or
flammable liquids, corrective measures shall be taken before work in the manhole is allowed
7. When nitrogen is used in manholes or confined areas, approved atmosphere testing devices
shall be placed in operation where they can be observed by people in the manhole. When
the testing devices show
a deficiency of oxygen, all personnel shall leave the manhole until
the proper atmosphere is restored.
8. The manhole shall be ventilated continuously when occupied.
9. An attendant is required topside with the
means to summon help without leaving his or her
station. The attendant shall be capable of instituting a rescue
without entering the manhole.
The attendant on the surface is responsible for the safety of the persons in the
10. The topside attendant can perform other duties outside of the enclosed space if these duties
do not distract the attendant from monitoring employees within the space. All manholes over
4 ft. deep should
be entered with the use of a ladder as required by 29 CFR 1910.269 (t)(1).
11. Workers should open all
entrance bars or chains on the topside of manhole guards before
entering or leaving a manhole. All chains or
bars should be closed at all other times, except
when raising or lowering tools or materials.
Operations involving chemical cleaning agents, solvents, volatile chemicals, cutting and
welding equipment, and
other hazardous agents or tools require additional consideration.
Consultation with and concurrence of
appropriate industrial safety and industrial hygiene
personnel are required.
13. The employee shall enter or leave a manhole by means of a ladder. The employer shall not
use a cable, cable hanger, or manhole rack as a support for climbing. A manhole ladder
should never be removed
while a worker is in the manhole unless absolutely necessary. In
the instance of a ladder being removed to make
it easier to rescue a worker, the topside
attendant shall fully devote his or her attention and efforts to
instituting a rescue using the
worker's body harness and lifeline if necessary. The ladder shall be replaced as
Note: The other workers in the hole should be warned that the ladder is to be removed in
time to allow him or her to exit the hole if necessary.
14. Materials, tools, and equipment should be kept
at a sufficient distance from the entrance to
the manhole to avoid any hazard to the occupant from falling
objects or from hot metal or
15. Blowtorches and furnaces should be ignited before
being lowered into manholes unless this
creates additional hazards.
16. Rags, tape, refuse, and
combustible and flammable materials should not be allowed to
accumulate in a manhole.
Instrumentation shall be calibrated per manufacturer's instructions. [See 29 CFR
1910.269(e)(8)]. A record of
calibration should be maintained.
18. GFCIs shall be used for 120-V ac power unless such power is supplied by a portable or
vehicle-mounted two-wire, single-phase generator rated not more than 5 kW, where the
circuit conductors of the generator are insulated from the generator frame and all other
(See Section 6.4).
19. All cables and insulated wires that do not have grounded conducting sheaths or
should be treated as bare conductors. They shall be considered energized unless approved
have been used to determine that they are deenergized. Barricade or cover these
conductors with protective
equipment or devices that will be within reach of a worker's
20. Where multiple cables are
present the cable to be worked on shall be identified by electrical
means unless its identity is obvious. [See
29 CFR 1910.269(t)(5)]. Where cable has one or
more abnormalities that could be an indication of an impending
fault, the defective cable
shall be deenergized, except when service load conditions and a lack of feasible
require that the cable remain energized. In that case, employees may enter the manhole if
are protected by the affects of the failure by flash blankets or other devices capable of
adverse effects of the fault. [See 29 CFR 1910.269(t)(7)].
7.10.2 WORKING ON ENERGIZED UNDERGROUND CABLES
In general, work should not be performed on energized
underground cables. However, strictly
external work, not requiring an appreciable change in location of the
cable, may be performed
under direct supervision. Energized cables that are to be moved shall be inspected for
[See 29 CFR 1910.269(t)(6)].
7.10.3 TERMINALS OF UNDERGROUND CABLES (POTHEADS)
work is started, the overhead line connections to a cable terminal upon which work is to
be performed should be
1. Deenergized and grounded or
2. Disconnected and covered with protective equipment.
Ferro-resonance can generate overvoltages of up to 12 times line-to-ground source voltage
upon opening of a single-phase device or a poorly synchronized three-phase device. Violent
failure can occur, exposing personnel to the high-voltage failure and accompanying conditions.
Ferro-resonant conditions can result in damage to lightning arresters, switching devices, buried
cable, transformers, and associated equipment.
Ferro-resonance can be initiated when all of the following
elements are present and the
switching means at dip point or takeoff is either a single-phase device or an
three-phase device that does not operate all phases within one-half cycle:
i. System grounded
at the source but with no ground at the transformer bank, such as a
transformer or transformer bank connected
delta on a grounded-wye system.
ii. Shielded cable or overhead conductor length sufficient to create the capacitance necessary.
iii. Transformer size that permits saturation of the iron core at the operating voltage
iv. Transformer unloaded or very lightly loaded.
Prevention or control of ferro-resonance may be
accomplished by any of the following
1. Using a wye-wye transformer connection with both
neutrals grounded and tied to the system
2. Using only phase-to-neutral (not phase-to-phase)
transformer connections for single-phase
3. Limiting length of underground cable between transformers and single-pole or poorly
synchronized three-pole switching devices.
4. If single-pole or poorly synchronized switching devices must
be used, ensuring that
transformer and underground cable are loaded in excess of 2% resistive load of the
5. If transformer primary is ungrounded-wye, temporarily grounding the neutrals of
transformers being switched.
6. Installing close-coupled, high-speed, three-pole switching devices
to minimize the duration
of the single-phase condition during opening and closing of the circuit
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