- 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
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.
responsibility for a worker's safety lies directly with the worker. This means that all
workers are 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
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.
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,
make a careful inspection to determine whether the structures are safe and
are properly 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
practice of 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 facility as
soon as possible.
6. The worker should
exercise care and good judgment when lifting heavy material, obtaining
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
they supervise. This includes; taking positive action to determine
and reduce, as necessary, the
hazards associated with their operations; instructing employees in safe work methods and
requirements; allowing only those employees that are qualified for the work to
perform the work; and ensuring that employees perform their
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.
Supervisors 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.
of supervisors include the following:
1. Provide instructions on safe practices for the crew and see that they are followed.
Periodically examine supervised employees on their knowledge of the safety rules and
approved emergency techniques.
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.
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
9. Prescribe, 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,
procedures, and other safety requirements in this section that pertain to their respective job
also be trained in and familiar with any other safety practices, including
applicable emergency procedures that are not specifically addressed
in this section but are
related to their work and necessary for their safety.
7.2.2 QUALIFIED EMPLOYEE TRAINING
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 electrical equipment.
Training may consist of a combination of classroom and on-the-job type.
7.3 JOB BRIEFINGS
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
with the job, work instructions involved, special precautions,
energy source controls, and
personal protective equipment requirements.
If the work or operations to be performed during the work
day are repetitive and similar, at least
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,
occur 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 hazards
involved in the job. A more extensive discussion shall be conducted if the work is complicated
extremely hazardous, or the employee cannot be expected to recognize and avoid the hazards
involved in the job.
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
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
Employees should wear shoes or boots that comply with the requirements of ANSI Z41. No
metal 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, buildings, or
trees in which work is being done. Workers shall wear hardhats when visiting or observing in
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
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 hazards.
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 resistant
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 during
an arc flash blends, para-aramid adds strength to a fabric to prevent the fabric from breaking
open 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 wool
comply if the fabric will not ignite and continue to burn under the conditions to which
employee 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.
184.108.40.206 ELECTRIC ARC HAZARDS
Electric shock is a widely recognized hazard and involves current flow through or on the body.
Burns from 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
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
current, 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
The proper clothing system will minimize or reduce the burn injury.
220.127.116.11 TYPES OF FIRE RESISTANT FABRICS
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.
All clothing worn by affected workers should be considered part of the employees protective
clothing system. This includes
rainwear, cold weather wear and underclothing. Protective
clothing should provide a good functional fit to increase the protection and comfort
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.
The following requirements apply:
1. Rubber gloves shall be of appropriate voltage rating for the work being performed.
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
exceeding 6 months.
3. Leather glove protectors shall be worn over rubber gloves except where leather
are 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 protectors.
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.
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
depending on the maximum voltage they are designed to protect against.
Insulating line hose (flexible hose) is used as an insulating
cover for electric conductors to
protect against accidental contacts. A lengthwise slit with overlapping sides permits the hose to
placed on conductors easily. It is available in various diameters, lengths, and compositions.
Insulating 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 synthetic elastomer,
usually square or rectangular in shape, designed to cover energized electrical
prevent direct accidental contact by electrical workers.
7.4.11 LIVE LINE TOOLS
A careful 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
Particular attention 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
the inserts 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
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 climb
or raise the bucket to a position just below the first line of conductors. When
should 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 manner.
As the workers ascend to their working position, they
shall cover all conductors which provide a
hazard. This should be done from below whenever possible. At no time shall workers pass
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 racks, and
transformers, they should be secured by wooden or plastic clamp pins or tie thongs. After the
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 ground.
7.4.16 CLEANING AND INSPECTING
After the rubber goods have been lowered to the ground, they should be cleaned and visually
before being placed in the carrier compartments of the truck.
7.5 PROTECTIVE GROUNDING OF LINES AND EQUIPMENT
Grounding is the
most effective way of protecting electrical workers from electric shock. That is
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
hold together with tape, pile materials on top of, or store blankets near vehicle heaters.
This section provides information
concerning protection for workers repairing, servicing, or
working on high-voltage power lines.
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
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
the line being worked, or there is a lightning strike near the line being worked.
The personal protective grounds should provide
a low-impedance path to ground to ensure
prompt operation of the circuit protective devices.
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
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
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
wires and 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 distance.
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 developed and
consensus standard for protective grounds, ASTM Designation: F-855. This
voluntary 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 with
protection from electric shock if grounds are sized, selected, and installed properly.
cables shall be available for use when work is being done on deenergized lines or
22.214.171.124 APPROVED CAPACITY
cables shall accommodate the maximum fault current to which the cable or
equipment might be subjected.
126.96.36.199 GROUNDING CABLES AND
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
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
discussed in the following subsections.
188.8.131.52 GROUNDING CABLES
Most of the grounding cables in use today (and available
for purchase) are actually
manufactured for 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
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 flexible
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
are 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 the filler
compound vent hole at the bottom of the cable so that employees can visually check that the
cable 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, the
recommendations should be followed.
184.108.40.206.4 HANDLING OF GROUNDING CABLE
Personal protective grounds are usually
handled and lifted by the cable. However, continuous
flexing eventually breaks the conductor strands beneath the jacket. Therefore, employees
should minimize the use of sharp bends in the cable.
220.127.116.11.5 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
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.
18.104.22.168.6 GROUNDING CABLE LENGTH
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
length, and excessive length could exceed the tolerable voltage drop across the body. Longer
cables also tend to twist or coil, which reduces the effectiveness of the cable.
22.214.171.124.7 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
connection to the conductor, metal structure, or ground wire/rod.
126.96.36.199.7.1 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
3. Other types of special clamps are designed for specific applications, such as cluster
equipment grounding, and so on.
188.8.131.52.7.2 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
products on 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
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
corrosion on 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
connecting to a tower leg or ground
184.108.40.206.8 GROUNDING CLUSTER BARS
When climbing wood-pole structures, workers may use a grounding cluster bar to connect
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 to
connect the three-phase cables and
a fourth cable to a riser from the station ground mat. When
installing personal grounds on wood structures from a bucket, the ground cables
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.
220.127.116.11.9 TEMPORARY GROUND RODS
typical examples of temporary ground rods used for grounding ungrounded structures or
mobile equipment, or during conductor splicing operations,
1. A minimum ⅝-inch diameter bronze, copper, or copper-weld rod at least 6 feet long, driven
to a depth of at least 5
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
8 feet 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 guys,
ground rods, maintenance vehicles, and structure legs or ground wires while they are bonded to
grounds which are in place. When it is absolutely necessary to work on or near these
features, 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
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
7.5.5 ATTACHING AND REMOVING GROUNDS
Employees attaching and removing grounds shall comply with the following:
1. Grounding equipment should be visually inspected and all mechanical connections checked
for tightness before each use.
surface to which the ground is to be attached should be clean before the grounding
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
before the ground end is disconnected.
7.5.6 GROUNDING METHODS AND LOCATION OF GROUNDS IN ORDER OF PREFERENCE
grounds shall install them using the information given in the following
18.104.22.168 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
placing everything at equal potential, eliminating the possibility of the lineworker getting in series
22.214.171.124 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.
126.96.36.199 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.
7.5.7 TESTING WITHOUT GROUNDS
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
necessary to protect each exposed employee in case previously grounded lines or equipment
7.5.8 GROUND PERSONNEL
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
use the appropriate equipment designed to prevent touch-and-step potential hazards. The term
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
each foot of the worker standing or walking in an electrical field created by high voltage
brought to earth.
7.6 INSTALLING OR REMOVING
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
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
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
difference of potential.
5. Rubber gloves of appropriate voltage rating shall be worn when working within reach of a
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
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 energized.
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
conductor. Where 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 as energized.
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 circuits.
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 of lines.
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 structures.
14. Except during emergency restoration activities, work from structures should be discontinued
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
capacity, operate smoothly, and be leveled and aligned in accordance with the
manufacturer's operating instructions.
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
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
grounds installed at every work location.
2. When workers are stringing adjacent to energized lines, the tension-stringing
other methods that prevent unintentional contact between the lines being pulled and any
worker should be used.
pulling and tensioning equipment should be effectively grounded.
4. A ground should be installed between the tensioning reel setup and the first structure to
ground each bare conductor, subconductor,
and overhead grounding conductor during
stringing across or adjacent to energized lines.
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.
6. Conductors, 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
conductors, 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
Line workers shall be familiar with special tools that are used for climbing, such as climber gaffs,
straps, and body belts shall properly store and maintain such equipment.
7.7.1 LINEWORKERS’ CLIMBING TOOLS
Employees should apply
1. All climbers should be inspected frequently by the worker using them.
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 replaced.
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
2. Workers shall use their body belts and safety straps when doing any work involving danger of
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
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 temperatures.
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 any
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
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.
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.
7.7.6 PIKE POLES
Pike poles shall comply with the following:
1. Cracked, broken, or slivered pike poles should not be
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 SHARP TOOLS
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
7.7.8 HANDLINES AND TAGLINES
Use high quality, nonconductive hand lines and taglines. Keep them stored in a clean,
location and protected from damage and contamination. Wear clean gloves when handling
hand 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 to
aid tree trimmers and protect them from hazards.
7.8.1 CARE AND USE OF TOOLS
shall be cared for using the following methods:
1. The handles of all tree-trimming tools shall be kept well dressed and varnished.
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.
4. All 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
constructed to withstand contact with
saws and other sharp objects. Workers in trees shall
be tied off.
7.9 SERIES STREET-LIGHTING CIRCUITS AND APPARATUS
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.
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
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.
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
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
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
ventilated 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 manhole
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
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 manhole.
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
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,
when raising or lowering tools or materials.
12. Operations involving chemical cleaning agents, solvents, volatile chemicals,
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
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
body harness and lifeline if necessary. The ladder shall be replaced as soon 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
16. Rags, tape, refuse, and combustible and flammable materials should not be allowed to
accumulate in a manhole.
17. Instrumentation shall be calibrated per manufacturer's instructions. [See 29 CFR
1910.269(e)(8)]. A record of calibration should
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
grounded surfaces. (See Section 6.4).
19. All cables and insulated wires that do not have grounded conducting sheaths or shielding
should be treated as bare conductors. They shall be considered energized unless approved
methods 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 alternatives
require that the cable remain energized. In
that case, employees may enter the manhole if
they are protected by the affects of the failure by flash blankets or other devices capable
containing the 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)
Before work is started, the overhead
line connections to a cable terminal upon which work is to
be performed should be either:
1. Deenergized and grounded or
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
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 unsynchronized
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
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 the
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