Understanding the Four Critical Boundaries

Arc flash protection is built upon a system of four distinct boundaries, each serving a specific protective function.

Limited Approach Boundary

The Limited Approach Boundary represents the distance from an energized component where
unqualified persons (those without proper electrical safety training) must not cross without escort. This
boundary serves as the outermost protective perimeter and is determined based on nominal system
voltage.
Unqualified individuals may only cross this boundary when they demonstrate a valid need and receive
continuous escort by qualified personnel. This first line of defense ensures that individuals without
proper training remain at a safe distance from potential electrical hazards.

Restricted Approach Boundary

The Restricted Approach Boundary establishes a more stringent protective zone that only qualified
electrical workers may enter. Within this boundary, specific PPE and insulated tools become
mandatory, and inadvertent movement must be prevented through proper work positioning. The risk of
electrical shock increases significantly due to proximity, and documented work permits are required
for any repair work inside this limit.

Arc Flash Boundary

Unlike the previous boundaries based on shock protection, the Arc Flash Boundary specifically
addresses thermal energy exposure. This critical boundary marks the distance at which
second-degree burns could occur during an arc flash incident. It requires determination through
incident energy calculations specific to each piece of equipment.
The Arc Flash Boundary may extend significantly farther than shock protection boundaries in certain
systems, sometimes reaching 20 feet or more for high-energy equipment. Anyone crossing this
threshold must wear appropriate arc-rated clothing and PPE matched to the estimated incident energy
levels.

Calculation Methodologies: Beyond the Simplified Tables

While NFPA 70E offers tables for estimating boundaries, comprehensive protection requires more
detailed calculation approaches.

Incident Energy Analysis Method

The incident energy analysis method applies IEEE 1584 calculation methodologies to determine
equipment-specific boundaries rather than relying on general categories. This engineering-based
approach accounts for system-specific factors including available fault current, protective device
clearing time, gap between conductors, working distance, system grounding configuration, and
enclosure type and size.
This method typically provides more precise PPE requirements and often reduces excessive PPE
compared to table methods. The calculations produce specific incident energy values measured in
calories per square centimeter (cal/cm²) at defined working distances, which directly correlate to PPE
arc ratings.
Organizations implementing this approach must maintain regular updates when system changes occur.
Modifications to electrical distribution systems, changes in protective device settings, or even routine
maintenance on circuit breakers can significantly alter arc flash boundaries, requiring recalculation and
relabeling.

Practical Implementation Strategies

Translating calculated boundaries into workplace practice requires systematic implementation
approaches that make abstract mathematical concepts visible and understandable in the field.

Equipment Labeling Systems

Effective labeling forms the cornerstone of boundary implementation. Equipment labels should clearly
display all relevant boundaries, indicate required PPE categories, and include incident energy values at
working distance. Consistency across the facility helps workers quickly recognize and interpret
boundary information regardless of which area they’re working in.
Advanced labeling systems incorporate color-coding for rapid recognition and may include QR codes
linking to detailed procedures for that specific equipment. Labels must include calculation dates for
verification and be constructed from materials capable of withstanding the environmental conditions
present in the installation location.

Temporary Boundary Marking

Maintenance and project work often require temporary boundary marking systems to create visible
reminders of invisible boundaries. Facilities typically deploy portable boundary tape stands at
calculated distances, with distinct colors representing different boundaries. Some organizations
implement digital projection systems for complex environments where traditional boundary marking
proves difficult.
Effective programs train workers on proper placement verification and create standardized boundary kit
contents available at job sites. Work permits should document actual boundary placement, particularly
in areas with overlapping boundaries from multiple energy sources.

Digital Boundary Management

Advanced organizations increasingly implement digital boundary tracking systems to enhance
traditional approaches. Mobile applications can display real-time boundary information specific to
equipment being serviced, while wearable technology can alert workers to boundary encroachment
before violations occur.
Some facilities utilize augmented reality displays showing boundaries in complex environments,
particularly useful in congested industrial settings. These systems often integrate with work order
management systems to ensure appropriate precautions appear automatically when work is scheduled
on specific equipment.

Training Methodologies for Boundary Awareness

Effective boundary training goes beyond concept explanation to develop practical application skills that
workers can implement in diverse field conditions.

Boundary Decision-Making Scenarios

Training should incorporate decision-making elements that reflect real-world complexity. Scenariobased exercises should present multiple boundaries requiring assessment, dynamic situations with
changing requirements, and emergency response protocols when boundaries are compromised.
Workers need clear understanding of authorization processes for boundary crossing and communication
protocols when working near boundaries. Documentation requirements for various boundary zones
should be practiced until they become second nature rather than burdensome administrative tasks.

Special Applications and Considerations

Certain situations require modified approaches to boundary management due to their unique challenges
or heightened risk profiles.

Complex Multi-Feed Equipment

Equipment with multiple power sources presents unique boundary management challenges. Safety
professionals must determine worst-case boundary scenarios accounting for all potential energy sources
and establish clear procedures for boundary hierarchy during partial de-energization.
Documentation systems must account for the complexity of these situations, with special labeling
requirements indicating multiple sources. Workers require specialized training on verification
procedures for all potential energy sources before boundaries can be modified or reduced.

Outdoor and Extreme Environments

Outdoor installations and extreme environments necessitate adaptations to standard boundary practices.
High-wind environments may require enhanced boundary marking methods, while wet or corrosive
atmospheres demand more durable marking solutions.
Extreme temperature environments affect both boundary implementation and PPE utilization. Cold
weather may require additional protective layers beneath arc-rated clothing, potentially affecting
movement and dexterity within restricted boundaries. Limited visibility conditions in outdoor settings
during night work or adverse weather require enhanced marking strategies to maintain boundary
awareness.

Continuous Process Environments

Facilities where shutdown is exceptionally costly require specialized boundary management
approaches. These organizations often implement remote monitoring and operation strategies to
minimize the need for boundary crossing during normal operations.
When boundaries must be crossed in these environments, enhanced PPE protocols and specialized
work practices help reduce risk while maintaining operational continuity. Many such facilities invest in
engineering controls specifically designed to reduce boundary zones, such as remote racking systems,
infrared viewing windows, and robotic inspection technologies.

Measuring Program Effectiveness

Evaluating boundary program effectiveness requires both leading and lagging indicators. Organizations
should track boundary procedure compliance rates, authorized versus unauthorized boundary crossings,
and worker competency assessment scores as leading indicators of program health.
Near-miss reporting related to boundary violations provides valuable insights for program
improvement, while PPE compliance verification at various boundaries helps identify potential training
gaps. Regular review of boundary documentation in work permits reveals how well theoretical
knowledge translates to field application.
Effective programs establish feedback mechanisms allowing qualified workers to suggest
improvements to boundary management systems based on field experience. This continuous
improvement approach recognizes that those working within the boundaries daily often develop the
most practical insights for enhancement.

Beyond Compliance to Culture

Effective arc flash boundary management extends beyond mere regulatory compliance, becoming
ingrained in organizational safety culture. By implementing comprehensive assessment protocols,
practical field applications, and engaging training methodologies, organizations transform abstract
calculations into tangible protection systems.
The most successful electrical safety programs recognize that boundaries represent more than
mathematical formulas or floor markings—they serve as critical decision points where worker
behavior, engineering controls, and administrative systems intersect to prevent catastrophic injuries.
Through proper implementation of these concepts, electrical workers can navigate hazardous
environments with the protection afforded by invisible but life-saving perimeters.

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Critical Electrical Safety Targets

Make sure these get done!

• De-energize. Unless the employer can justify live work, it is not permitted. Live testing and troubleshooting are allowed, but altering the circuit live is difficult to justify.
• Workers must be qualified for each electrical task they perform, and the electrical hazard they are exposed to.
• Workers must know how to perform a risk assessment, and how to reduce the associated risk.
• A worker must have access to and utilize the appropriate PPE for the electrical hazard.
• Employers need to ensure the worker has access to arc-rated PPE throughout the range of incident energy indicated by their incident energy analysis.
• Test-Before-Touch. A qualified worker must verify zero energy before contacting de-energized parts by performing the Live-Dead-Live test.
• While verifying zero energy, the qualified worker must utilize appropriate PPE and insulated tools.
• All PPE, as well as all tools and equipment with electrical insulation, must be inspected daily before each use.
• The owner of the electrical equipment is responsible for providing labels that include nominal voltage, arc flash boundary, and a method of determining the appropriate arc flash  PPE to be worn.
• Rubber insulated gloves must be electrically tested every six months.
• Arc-rated clothing and insulated gloves must fit the user, and provide full coverage.

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Based on the number of questions I get from clients, the electrical safety-related OSHA training requirements can be confusing. In simple terms, a company has to provide electrical safety-related work practices and train employees on them. A worker has to be qualified, trained and can demonstrate skills, on any task they are to perform when exposed to electrical hazards. How much training is required? Enough to accomplish that.

Below in OSHA’s words:

1910.332

1910.332(a)
Scope. The training requirements contained in this section apply to employees who face a risk of electric shock that is not reduced to a safe level by the electrical installation requirements of 1910.303 through 1910.308.

Note: Employees in occupations listed in Table S-4 face such a risk and are required to be trained. Other employees who also may reasonably be expected to face comparable risk of injury due to electric shock or other electrical hazards must also be trained.
1910.332(b)
Content of training.
1910.332(b)(1)
Practices addressed in this standard. Employees shall be trained in and familiar with the safety-related work practices required by 1910.331 through 1910.335 that pertain to their respective job assignments.
1910.332(b)(2)
Additional requirements for unqualified persons. Employees who are covered by paragraph (a) of this section but who are not qualified persons shall also be trained in and familiar with any electrically related safety practices not specifically addressed by 1910.331 through 1910.335 but which are necessary for their safety.
1910.332(b)(3)
Additional requirements for qualified persons. Qualified persons (i.e. those permitted to work on or near exposed energized parts) shall, at a minimum, be trained in and familiar with the following:
1910.332(b)(3)(i)
The skills and techniques necessary to distinguish exposed live parts from other parts of electric equipment.
1910.332(b)(3)(ii)
The skills and techniques necessary to determine the nominal voltage of exposed live parts, and
1910.332(b)(3)(iii)
The clearance distances specified in 1910.333(c) and the corresponding voltages to which the qualified person will be exposed.

Note 1: For the purposes of 1910.331 through 1910.335, a person must have the training required by paragraph (b)(3) of this section in order to be considered a qualified person.

Note 2: Qualified persons whose work on energized equipment involves either direct contact or contact by means of tools or materials must also have the training needed to meet 1910.333(C)(2).
1910.332(c)
Type of training. The training required by this section shall be of the classroom or on-the-job type. The degree of training provided shall be determined by the risk to the employee.

1910.333

1910.333(a)
“General.” Safety-related work practices shall be employed to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts, when work is performed near or on equipment or circuits which are or may be energized. The specific safety-related work practices shall be consistent with the nature and extent of the associated electrical hazards.
1910.333(a)(1)
“Deenergized parts.” Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.
Note 1: Examples of increased or additional hazards include interruption of life support equipment, deactivation of emergency alarm systems, shutdown of hazardous location ventilation equipment, or removal of illumination for an area.
Note 2: Examples of work that may be performed on or near energized circuit parts because of infeasibility due to equipment design or operational limitations include testing of electric circuits that can only be performed with the circuit energized and work on circuits that form an integral part of a continuous industrial process in a chemical plant that would otherwise need to be completely shut down in order to permit work on one circuit or piece of equipment.
Note 3: Work on or near deenergized parts is covered by paragraph (b) of this section.
..1910.333(a)(2)
1910.333(a)(2)
“Energized parts.” If the exposed live parts are not deenergized (i.e., for reasons of increased or additional hazards or infeasibility), other safety-related work practices shall be used to protect employees who may be exposed to the electrical hazards involved. Such work practices shall protect employees against contact with energized circuit parts directly with any part of their body or indirectly through some other conductive object. The work practices that are used shall be suitable for the conditions under which the work is to be performed and for the voltage level of the exposed electric conductors or circuit parts. Specific work practice requirements are detailed in paragraph (c) of this section.
1910.333(b)
“Working on or near exposed deenergized parts.”
1910.333(b)(1)
“Application.” This paragraph applies to work on exposed deenergized parts or near enough to them to expose the employee to any electrical hazard they present. Conductors and parts of electric equipment that have been deenergized but have not been locked out or tagged in accordance with paragraph (b) of this section shall be treated as energized parts, and paragraph (c) of this section applies to work on or near them.
1910.333(b)(2)
“Lockout and Tagging.” While any employee is exposed to contact with parts of fixed electric equipment or circuits which have been deenergized, the circuits energizing the parts shall be locked out or tagged or both in accordance with the requirements of this paragraph. The requirements shall be followed in the order in which they are presented (i.e., paragraph (b)(2)(i) first, then paragraph (b)(2)(ii), etc.).
Note 1: As used in this section, fixed equipment refers to equipment fastened in place or connected by permanent wiring methods.
Note 2: Lockout and tagging procedures that comply with paragraphs (c) through (f) of 1910.147 will also be deemed to comply with paragraph (b)(2) of this section provided that:
[1] The procedures address the electrical safety hazards covered by this Subpart; and
[2] The procedures also incorporate the requirements of paragraphs (b)(2)(iii)(D) and (b)(2)(iv)(B) of this section.
1910.333(b)(2)(i)

Checkout Our Practical Guide To Arc Flash And NFPA 70E

“Procedures.” The employer shall maintain a written copy of the procedures outlined in paragraph (b)(2) and shall make it available for inspection by employees and by the Assistant Secretary of Labor and his or her authorized representatives.
Note: The written procedures may be in the form of a copy of paragraph (b) of this section.
..1910.333(b)(2)(ii)
1910.333(b)(2)(ii)
“Deenergizing equipment.”
1910.333(b)(2)(ii)(A)
Safe procedures for deenergizing circuits and equipment shall be determined before circuits or equipment are deenergized.
1910.333(b)(2)(ii)(B)
The circuits and equipment to be worked on shall be disconnected from all electric energy sources. Control circuit devices, such as push buttons, selector switches, and interlocks, may not be used as the sole means for deenergizing circuits or equipment. Interlocks for electric equipment may not be used as a substitute for lockout and tagging procedures.
1910.333(b)(2)(ii)(C)
Stored electric energy which might endanger personnel shall be released. Capacitors shall be discharged and high capacitance elements shall be short-circuited and grounded, if the stored electric energy might endanger personnel.
Note: If the capacitors or associated equipment are handled in meeting this requirement, they shall be treated as energized.
1910.333(b)(2)(ii)(D)
Stored non-electrical energy in devices that could reenergize electric circuit parts shall be blocked or relieved to the extent that the circuit parts could not be accidentally energized by the device.
1910.333(b)(2)(iii)
“Application of locks and tags.”
1910.333(b)(2)(iii)(A)
A lock and a tag shall be placed on each disconnecting means used to deenergize circuits and equipment on which work is to be performed, except as provided in paragraphs (b)(2)(iii)(C) and (b)(2)(iii)(E) of this section. The lock shall be attached so as to prevent persons from operating the disconnecting means unless they resort to undue force or the use of tools.
..1910.333(b)(2)(iii)(B)
1910.333(b)(2)(iii)(B)
Each tag shall contain a statement prohibiting unauthorized operation of the disconnecting means and removal of the tag.
1910.333(b)(2)(iii)(C)
If a lock cannot be applied, or if the employer can demonstrate that tagging procedures will provide a level of safety equivalent to that obtained by the use of a lock, a tag may be used without a lock.
1910.333(b)(2)(iii)(D)
A tag used without a lock, as permitted by paragraph (b)(2)(iii)(C) of this section, shall be supplemented by at least one additional safety measure that provides a level of safety equivalent to that obtained by use of a lock. Examples of additional safety measures include the removal of an isolating circuit element, blocking of a controlling switch, or opening of an extra disconnecting device.
1910.333(b)(2)(iii)(E)
A lock may be placed without a tag only under the following conditions:
1910.333(b)(2)(iii)(E)(1)
Only one circuit or piece of equipment is deenergized, and
1910.333(b)(2)(iii)(E)(2)
The lockout period does not extend beyond the work shift, and
1910.333(b)(2)(iii)(E)(3)
Employees exposed to the hazards associated with reenergizing the circuit or equipment are familiar with this procedure.
..1910.333(b)(2)(iv)
1910.333(b)(2)(iv)
Verification of deenergized condition. The requirements of this paragraph shall be met before any circuits or equipment can be considered and worked as deenergized.
1910.333(b)(2)(iv)(A)
A qualified person shall operate the equipment operating controls or otherwise verify that the equipment cannot be restarted.
1910.333(b)(2)(iv)(B)
A qualified person shall use test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall verify that the circuit elements and equipment parts are deenergized. The test shall also determine if any energized condition exists as a result of inadvertently induced voltage or unrelated voltage backfeed even though specific parts of the circuit have been deenergized and presumed to be safe. If the circuit to be tested is over 600 volts, nominal, the test equipment shall be checked for proper operation immediately after this test.
1910.333(b)(2)(v)
“Reenergizing equipment.” These requirements shall be met, in the order given, before circuits or equipment are reenergized, even temporarily.
1910.333(b)(2)(v)(A)
A qualified person shall conduct tests and visual inspections, as necessary, to verify that all tools, electrical jumpers, shorts, grounds, and other such devices have been removed, so that the circuits and equipment can be safely energized.
..1910.333(b)(2)(v)(B)
1910.333(b)(2)(v)(B)
Employees exposed to the hazards associated with reenergizing the circuit or equipment shall be warned to stay clear of circuits and equipment.
1910.333(b)(2)(v)(C)
Each lock and tag shall be removed by the employee who applied it or under his or her direct supervision. However, if this employee is absent from the workplace, then the lock or tag may be removed by a qualified person designated to perform this task provided that:
1910.333(b)(2)(v)(C)(1)
The employer ensures that the employee who applied the lock or tag is not available at the workplace, and
1910.333(b)(2)(v)(C)(2)
The employer ensures that the employee is aware that the lock or tag has been removed before he or she resumes work at that workplace.
1910.333(b)(2)(v)(D)
There shall be a visual determination that all employees are clear of the circuits and equipment.
1910.333(c)
“Working on or near exposed energized parts.”
1910.333(c)(1)
“Application.” This paragraph applies to work performed on exposed live parts (involving either direct contact or by means of tools or materials) or near enough to them for employees to be exposed to any hazard they present.
..1910.333(c)(2)
1910.333(c)(2)
“Work on energized equipment.” Only qualified persons may work on electric circuit parts or equipment that have not been deenergized under the procedures of paragraph (b) of this section. Such persons shall be capable of working safely on energized circuits and shall be familiar with the proper use of special precautionary techniques, personal protective equipment, insulating and shielding materials, and insulated tools.
1910.333(c)(3)
“Overhead lines.” if work is to be performed near overhead lines, the lines shall be deenergized and grounded, or other protective measures shall be provided before work is started. If the lines are to be deenergized, arrangements shall be made with the person or organization that operates or controls the electric circuits involved to deenergize and ground them. If protective measures, such as guarding, isolating, or insulating, are provided, these precautions shall prevent employees from contacting such lines directly with any part of their body or indirectly through conductive materials, tools, or equipment.
Note: The work practices used by qualified persons installing insulating devices on overhead power transmission or distribution lines are covered by 1910.269 of this Part, not by 1910.332 through 1910.335 of this Part. Under paragraph (c)(2) of this section, unqualified persons are prohibited from performing this type of work.
1910.333(c)(3)(i)
“Unqualified persons.”
1910.333(c)(3)(i)(A)
When an unqualified person is working in an elevated position near overhead lines, the location shall be such that the person and the longest conductive object he or she may contact cannot come closer to any unguarded, energized overhead line than the following distances:
1910.333(c)(3)(i)(A)(1)
For voltages to ground 50kV or below – 10 feet (305 cm);
1910.333(c)(3)(i)(A)(2)
For voltages to ground over 50kV – 10 feet (305 cm) plus 4 inches (10 cm) for every 10kV over 50kV.
..1910.333(c)(3)(i)(B)
1910.333(c)(3)(i)(B)
When an unqualified person is working on the ground in the vicinity of overhead lines, the person may not bring any conductive object closer to unguarded, energized overhead lines than the distances given in paragraph (c)(3)(i)(A) of this section.
Note: For voltages normally encountered with overhead power line, objects which do not have an insulating rating for the voltage involved are considered to be conductive.
1910.333(c)(3)(ii)
“Qualified persons.” When a qualified person is working in the vicinity of overhead lines, whether in an elevated position or on the ground, the person may not approach or take any conductive object without an approved insulating handle closer to exposed energized parts than shown in Table S-5 unless:
1910.333(c)(3)(ii)(A)
The person is insulated from the energized part (gloves, with sleeves if necessary, rated for the voltage involved are considered to be insulation of the person from the energized part on which work is performed), or
1910.333(c)(3)(ii)(B)
The energized part is insulated both from all other conductive objects at a different potential and from the person, or
1910.333(c)(3)(ii)(C)
The person is insulated from all conductive objects at a potential different from that of the energized part.

..1910.333(c)(3)(iii)
1910.333(c)(3)(iii)
“Vehicular and mechanical equipment.”
1910.333(c)(3)(iii)(A)
Any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines shall be operated so that a clearance of 10 ft. (305 cm) is maintained. If the voltage is higher than 50kV, the clearance shall be increased 4 in. (10 cm) for every 10kV over that voltage. However, under any of the following conditions, the clearance may be reduced:
1910.333(c)(3)(iii)(A)(1)
If the vehicle is in transit with its structure lowered, the clearance may be reduced to 4 ft. (122 cm). If the voltage is higher than 50kV, the clearance shall be increased 4 in. (10 cm) for every 10 kV over that voltage.
1910.333(c)(3)(iii)(A)(2)
If insulating barriers are installed to prevent contact with the lines, and if the barriers are rated for the voltage of the line being guarded and are not a part of or an attachment to the vehicle or its raised structure, the clearance may be reduced to a distance within the designed working dimensions of the insulating barrier.
1910.333(c)(3)(iii)(A)(3)
If the equipment is an aerial lift insulated for the voltage involved, and if the work is performed by a qualified person, the clearance (between the uninsulated portion of the aerial lift and the power line) may be reduced to the distance given in Table S-5.
1910.333(c)(3)(iii)(B)
Employees standing on the ground may not contact the vehicle or mechanical equipment or any of its attachments, unless:
1910.333(c)(3)(iii)(B)(1)
The employee is using protective equipment rated for the voltage; or
..1910.333(c)(3)(iii)(B)(2)
1910.333(c)(3)(iii)(B)(2)
The equipment is located so that no uninsulated part of its structure (that portion of the structure that provides a conductive path to employees on the ground) can come closer to the line than permitted in paragraph (c)(3)(iii) of this section.
1910.333(c)(3)(iii)(C)
If any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines is intentionally grounded, employees working on the ground near the point of grounding may not stand at the grounding location whenever there is a possibility of overhead line contact. Additional precautions, such as the use of barricades or insulation, shall be taken to protect employees from hazardous ground potentials, depending on earth resistivity and fault currents, which can develop within the first few feet or more outward from the grounding point.
1910.333(c)(4)
“Illumination.”
1910.333(c)(4)(i)
Employees may not enter spaces containing exposed energized parts, unless illumination is provided that enables the employees to perform the work safely.
1910.333(c)(4)(ii)
Where lack of illumination or an obstruction precludes observation of the work to be performed, employees may not perform tasks near exposed energized parts. Employees may not reach blindly into areas which may contain energized parts.
..1910.333(c)(5)
1910.333(c)(5)
“Confined or enclosed work spaces.” When an employee works in a confined or enclosed space (such as a manhole or vault) that contains exposed energized parts, the employer shall provide, and the employee shall use, protective shields, protective barriers, or insulating materials as necessary to avoid inadvertent contact with these parts. Doors, hinged panels, and the like shall be secured to prevent their swinging into an employee and causing the employee to contact exposed energized parts.
1910.333(c)(6)
“Conductive materials and equipment.” Conductive materials and equipment that are in contact with any part of an employee’s body shall be handled in a manner that will prevent them from contacting exposed energized conductors or circuit parts. If an employee must handle long dimensional conductive objects (such as ducts and pipes) in areas with exposed live parts, the employer shall institute work practices (such as the use of insulation, guarding, and material handling techniques) which will minimize the hazard.
1910.333(c)(7)
“Portable ladders.” Portable ladders shall have nonconductive siderails if they are used where the employee or the ladder could contact exposed energized parts.
1910.333(c)(8)
“Conductive apparel.” Conductive articles of jewelry and clothing (such a watch bands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread, or metal headgear) may not be worn if they might contact exposed energized parts. However, such articles may be worn if they are rendered nonconductive by covering, wrapping, or other insulating means.
..1910.333(c)(9)
1910.333(c)(9)
“Housekeeping duties.” Where live parts present an electrical contact hazard, employees may not perform housekeeping duties at such close distances to the parts that there is a possibility of contact, unless adequate safeguards (such as insulating equipment or barriers) are provided. Electrically conductive cleaning materials (including conductive solids such as steel wool, metalized cloth, and silicon carbide, as well as conductive liquid solutions) may not be used in proximity to energized parts unless procedures are followed which will prevent electrical contact.
1910.333(c)(10)
“Interlocks.” Only a qualified person following the requirements of paragraph (c) of this section may defeat an electrical safety interlock, and then only temporarily while he or she is working on the equipment. The interlock system shall be returned to its operable condition when this work is completed.
[55 FR 32016, Aug. 6, 1990; 55 FR 42053, Nov. 1, 1990; as amended at 59 FR 4476, Jan. 31, 1994]
Go to www.OSHA.gov for full text of the OSHA regulations.

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Introduction

This control panel is like thousands of control panels out in facilities today, and maybe even many in your facility. It controls a machine on the factory floor. It has four motor starters, individual circuit breakers for those motor circuits, ice cube relays, small fuses, and a control transformer. And on the door there are pushbuttons, indicating lights, rotary switches. In the lower right

corner of the panel is the main circuit breaker. With the door closed, we can still operate the breaker through the hole in the door. Pretty typical of many control panels. The question is how do we de-energize this panel to establish an electrically safe work condition.

Circuit Breakers

Circuit breakers have a line and load side. The line side is where the incoming power is connected. The load side is where the downstream loads are connected. In this case, the downstream loads are everything else in this panel and all of the motors and other components in the control circuit outside the panel. Everything downstream from this main breaker is being protected from over-currents by this breaker.

The question is, does this circuit breaker de-energize this panel? The answer is no. Opening this breaker de-energizes everything in this panel as well as the downstream loads, everything except for the line side of the breaker itself. When this circuit breaker is opened, turned off, the line side of the breaker is still hot. With the line side still energized by the incoming power, the panel has to be considered energized because the main breaker still has a shock and arc flash hazard. You could not use this breaker to establish an electrically safe work condition for this panel.

Electrically Safe Work Condition

To properly de-energize this panel to establish an electrically safe work condition, you would need to locate the circuit breaker or disconnect that feeds power to your control panel. Your lockout tagout procedures should indicate the location of this breaker or disconnect. Once that is found you would open that disconnect or circuit breaker and apply your locks and tag. Return to the control panel and follow through with all of the required lockout tagout procedures. The most important of which is the live-dead-live test to verify zero voltage. Always Test-Before-Touch. And of course, always wear the required PPE while verifying zero volts. Every circuit has to be considered energized until you’ve proven it’s not.

Troubleshooting Example 1

As a troubleshooting example, let us use a situation in which the operator of this machine reports that one of its four conveyors stopped running. You show up and ask the operator what led up to this problem, and they state that that conveyor has been making a lot more noise than usual. A squealing sound. You suspect a mechanical problem, and on an inspection of the conveyor pulleys, it is evident that a bearing has failed thus causing too much load on the motor. Next, we go to the control panel and see that it has an arc flash label that states an arc flash rating of 11 cal/cm2 and a voltage of 480. We must don the appropriate PPE to protect you from such an arc flash and voltage. Because we are only going to do a visual inspection and we are wearing the proper PPE we can proceed. We do an orderly shutdown of everything the panel controls then open the main breaker. We then open the control panel door and see that the motor starter has tripped for that motor. Everything else in the panel appears fine, we reset the motor starter, and close the door. We place our lock and tag on the main breaker, and we perform all other procedures required by our lockout tagout procedures and proceed to repair the bearing.

Troubleshooting Example 2

In the next example, the operator reported the conveyor wouldn’t turn on. There was no mention of a squealing noise. During our initial troubleshooting, we attempt to turn on that conveyor manually and we hear the motor starter turn on, or pull-in as we say,  inside the cabinet. But, the conveyor is still not moving. We don the appropriate PPE, open the control panel door and begin our visual inspection of the panel. We immediately notice the motor starter for conveyor four is showing signs of heat damage. A  dark smoke-like film is on the area covering the motor starter contacts. This, we know from experience, is an indication of poor contact being made by the starter contacts. The other starters don’t show this damage. Now we know we are going to have to remove and replace the starter or at least disassemble it for inspection and repair. In either case, we’ll need to completely de-energize the panel. At this time we’ll need to close the control panel door and open the main breaker. We then must go to the upstream circuit breaker for this panel, turn it off and apply our lock and tag. Upon returning to the control panel, wearing the appropriate PPE we open the control panel door. Using an appropriate volt-meter, we test that meter on a known live circuit, then measure incoming line leads phase-to-phase and phase-to-ground and do verify that we indeed have zero volts. We then retest the meter on a known live circuit to confirm the meter is still working. That is the Live-Dead-Live test. Now we can remove the PPE and begin our repair work. We find the contacts badly damaged from not making proper contact and the carbon buildup inside the starter is preventing the contact assembly from moving freely. We replace the motor starter, and now all conveyors are working fine.

A Shield May Not Work

Some people have suggested that if you add a plastic or metal shield to the main breaker that covers the energized line leads that should solve the problem. It actually can create a whole new problem. OSHA requires electrical equipment to be “accepted, or certified, or listed, or labeled, or otherwise determined to be safe by a nationally recognized testing laboratory.” Underwriters Laboratory is such a lab. If you add a plastic or metal shield to your breaker, it is no-longer UL Listed because it didn’t have your shield when tested. The shield could cause the breaker to operate differently than when it was manufactured and tested, resulting in an unsafe situation.

Control Panel Design

This next piece of advice doesn’t help you with existing control panels but could make your future panels safer and easier to work with where 70E is concerned. That advice is to ask the OEM of your new panels to put this main breaker in a separate box on the side of the panel. Putting the main circuit breaker in a separate enclosure is becoming quite common now, and manufacturers of these boxes are offering this option. Hoffman’s SEQUESTR line of enclosures is one such offering.

Circuit Breaker Panel Boards

I used a control panel as an example here, but all of this applies to circuit breaker panel boards as well, not just control panels. Opening the main breaker of a circuit breaker panel does not establish an electrically safe work condition. If you’re going to add a circuit breaker, for example, turning off the main breaker for the panel board is not sufficient. You will need to open the circuit breaker that feeds this panel to establish an electrically safe work condition.

Conclusion

In conclusion, it is essential that we know what does and what does not make an electrical panel electrically safe. It must be spelled out in your lockout/tagout procedures which disconnect, or circuit breaker removes power from the equipment that will enable us to create the electrically safe work condition. We will wear the appropriate PPE any time the equipment has an energized circuit component above 50V.

Relevant courses

The post The Main Circuit Breaker For This Control Panel Doesn’t De-energize The Panel appeared first on ElectricalTrainingPro.com.

Avoiding tight fitting clothing is essential if that clothing is being worn to protect you against the thermal effects of an arc flash. NFPA 70E states that the worker must avoid tight-fitting arc flash gear and that loose fitting clothes provide more thermal protection because of the “air spaces.” I often see and hear about companies adopting the policy of one single arc flash suit should take care of all of our needs. The maintenance department can share the same suit. The policy of one arc flash suit for the entire maintenance department is a big mistake.

An arc flash suit is the heavier arc flash protection needed in incident energy exposures generally above 25 cal/cm2. Arc flash suit hoods are required for any energy above 12 cal/cm2. The issue is this. If one of the maintenance people in your group is 6 foot 4 inches tall and weighs north of 300 pounds and another worker is 5 foot 7 inches and weighs 160, they can’t wear the same suit. But, I have seen situations where this is precisely the case. It is an impossibility that two people with substantially different body types can wear the same suit, and for safety reasons, they shouldn’t be wearing the same suit.

The reason an ill-fitting suit is a problem is that loose fitting arc rated clothing gives you more thermal protection than tight clothes, and, in addition to that, the wrong size suit can obstruct movement preventing you from completing the task safely. What if a major league baseball team all had to wear the same size uniform? I don’t think the fielding, throwing or hitting would be as good because their movements would be restricted. Go Cubs. I am here to argue that an arc flash suit is more important than a baseball uniform. To ensure that everyone is fitted correctly and the equipment properly stored and cared for, professional teams employ an equipment manager. Maybe your facility needs an equipment manager. I know you aren’t working with the same equipment budget as the Yankees. But how nice would that be?

Besides restricting movement, sleeves that are too short can be an issue if you extend your arm and your sleeve no-longer reaches your hand; subsequently, your wrist and forearm become exposed. 70E requires that the arc flash clothing provides full coverage.

One of my favorite comedy scenes in a movie has to be the “Fat Guy In A Little Coat” scene in Tommy Boy. Not surprisingly, small of stature, David Spade’s sports coat did not fit Chris Farley, with hilarious results. Funny in a movie, not amusing with PPE.

Manufacturers and distributors, on their websites, have detailed sizing charts for assisting you in getting the arc flash suit that fits your body. Head to toe measurements are included, and there are different sizing charts for men and women. Most want your chest, waste, height, other manufacturers need your arm length, inseam, among other measurements. One manufacturer states in the sizing instructions that workers under 5’8” and taller than 6’4” need to have a custom suit. Other manufacturers offer sm, med, LG, XL, XXL, XXXL. You would have to figure where you are on this type of a scale.

Here are links to a couple sizing charts:  Oberon    National Safety Apparel

Arc flash suits are expensive, and I certainly understand why companies want to limit the costs of implementing NFPA 70E.  Your company needs to develop a plan for ensuring all qualified workers have the appropriate suit to wear.

Arc flash suits come in a variety of types. You can purchase bib overall type pants and an accompanying jacket and hood. There are regular type pants, with a jacket and hood. It is important that you shop around, look at many websites of manufacturers and distributors. Look at all of the sizing options and determine what is right for you.

A comment I have heard on more than one occasion is, “I don’t want to wear an arc flash suit that someone else has been sweating in.” Good point, I wouldn’t either. Let me state right now, that in my opinion, the only live work we should be doing in an arc flash suit is verifying zero volts during our live-dead-live test required for lockout tagout. Our first step in providing protective measures after we have completed a risk assessment is the elimination of the hazard. Working de-energized. This, of course, will require us to establish an Electrically Safe Work Condition (ESWC). So hopefully no one is wearing an arc flash suit for an extended period of time. I do realize on really hot and humid days you don’t have to wear them very long before you are sweaty.

Arc flash suits have to be stored in such a way that they won’t become damaged. A dedicated cabinet, storage closet or bags will help limit the damage. Some people turn them inside out to help them dry and avoid mold and the suit getting stinky. One helpful accessory that is available is a cooling unit which is a blower that mounts to the suit and provides air flow throughout the suit as you wear it. Another accessory is cooling vests designed to be worn under an arc flash suit.

Your facility needs to have suits in various sizes so all qualified workers are protected through the range of arc flash exposures. This is an expensive garment performing the critical function of protecting the wearer from a high energy arc flash event. A lot of thought needs to go into the proper sizing of arc flash suits and how many we need to buy.

Our Training That Addresses This Issue

The post One Arc Flash Suit For The Entire Maintenance Department Is A Big Mistake appeared first on ElectricalTrainingPro.com.

Practical Guide To Arc Flash and NFPA 70E

By: Daryn Lewellyn

I began my first job in electrical maintenance when I was hired in at Terre Haute Malleable and Manufacturing Company in 1984; a long-since-closed iron foundry in Terre Haute, Indiana. It was a one-hundred-year-old facility, dark, with dirt floors made of sand and coal dust and known by the workers as The Malleable. Some of my most memorable work experiences happened in the four short months I worked there. I remember not receiving any electrical safety training.

I remember when an older electrician named Bill gave me the arc flash training. It wasn’t called arc flash training because none of us had ever heard that phrase before. We didn’t know what happened when panels blew up or that it had a name. The information was given as somber advice while we were standing in front of a large disconnect. Bill said, “When you open or close one of these big disconnects don’t stand in front of it. Stand off to the side, use your left hand, turn your head and it might not hurt to duck a little.” I asked why and he said, “sometimes these things blow up.” That was good advice then and is still relevant today.  The problem was that in 1984 that advice was the entire arc flash class. That was all we knew. Several years later I was repairing a variable frequency drive when part of it exploded when I closed the breaker. I was standing off to the side and was not injured. Thanks, Bill.

Thirty years ago we wrapped electrical tape around screwdrivers and called them insulated. We thought the plastic dipped handles on our Klein lineman’s pliers made them safe. Channel locks were fuse pullers. We wore polyester shirts and gold chains, and our only PPE was a hard hat, steel-toed shoes and safety glasses.

A lot has changed in regards to electrical safety and electrical safety training in the decades since. Arc-rated clothing has replaced our polyester shirts, voltage-rated insulated tools have replaced electrical tape, and most importantly, awareness of electrical hazards has replaced our ignorance. We can no longer work as we did back then, and we have to receive training on electrical hazards. In the ten years, I worked in factories, my employer never gave me formal electrical safety training. The first electrical safety class I was a part of I was the instructor.

In this Practical Guide To Arc Flash and NFPA 70E, I hope to simplify parts of the standard. This guide is not going to answer every question you have, and it doesn’t address every article in 70E. What I am hoping to accomplish with this guide is to help you understand the standards’ most impactful sections and to give you guidance on whether your facility needs more work on your overall electrical safety program.

As I travel the country providing 70E training and consulting for my clients, I have recognized a need for a guide like this. I wrote this guide for qualified workers, managers, and supervisors to assist them in making people safer while working around electrical hazards. Whether you call the training electrical safety training, 70E training, or arc flash training, it is a good idea to read this guide first as it may generate some good questions to have clarified during your training.

Access To The 70E Standard

Every facility, company or organization needs an easily accessible copy of 70E. I like the pdf version because it’s searchable and you can access it over a network.

I also think the 70E Handbook is a handy tool. It has interpretations, explanations and added material, not in the 70E standard. The Handbook can be purchased as an eBook and read on a tablet, Kindle or your phone. Wherever I am, I have 70E and the handbook on my phone. I also keep the OSHA regulations 1910.301 – 308, 1910.331 – 335, and 1910.399 at my fingertips, and all searchable.

Electrical Safety Responsibilities

Both OSHA and 70E agree on what the employers’ and the employees’ responsibilities are when it comes to electrical safety. Both require the employer to establish, implement, and document electrical safe work practices and procedures. And to train their employees on them. The employee’s responsibility is to comply with these work practices. These work practices will include many things, such as de-energizing equipment, PPE, risk assessments, approach boundaries, etc. The priority of these work practices must be the elimination of the hazard. De-energize the circuit, use the live-dead-live test to verify that it is de-energized.

Using arguments like we can’t afford the downtime, production won’t let us shut it down, and the boss or client say’s we have to work live, do not work anymore. These things are money issues and have no place in the decision-making process when we are de-energizing equipment. When a facility decides to work energized because it might save money they needlessly put workers in a possibly fatal situation. The world will not end if you experience a short downtime.

Exposure To Electrical Hazards

If a worker is about to begin a task that will be exposing them to electrical hazards a few things need to be clear. First, the worker has to be qualified for the work they are about to undertake. They must be able to demonstrate that they understand the equipment operation and construction, have received training on the hazards present, and have been trained on how to reduce the associated risks. The employer must document when the qualified worker received electrical safety training and the contents of that training when they demonstrated their proficiency with the work practices, and retain the documentation for the duration of their employment.

A helpful way to prepare for this is to imagine OSHA walking into your facility and asking if the worker they see using a voltmeter is qualified for the work they are doing. How would you answer and what documentation would you be able to provide to make your case?

Next, assuming we have determined the worker is qualified, we need to look at the task they are about to perform. Let us use as an example of adding a circuit breaker to a 480/277 volt panel-board labeled “Panel-A.” OSHA and 70E agree that we can’t do this work energized. Thirty years ago we may have inserted or removed a circuit breaker while the panel was live. But not today.

OSHA and 70E both require circuits above 50 volts be de-energized before work proceeding. Unless de-energizing would cause increased or additional hazards, such as life support systems at a hospital, or alarm systems. We are also allowed to work energized if it is infeasible to de-energize the circuit. I can tell you OSHA doesn’t believe many things are infeasible. Measuring voltage during the commissioning and startup equipment, measuring voltage and current during troubleshooting, for example, are allowed because it is infeasible to measure voltage and current if the circuit is de-energized. Just because it is acceptable doesn’t mean you have to permit it. Many companies do not. We may also have to work de-energized on circuits below 50 volts if they present a potential arc flash hazard.

OSHA requires you to work energized in one critical task. Lockout/Tagout. One of the steps of LOTO is verifying you have zero volts on the circuit you just de-energized. You must consider every conductor energized until you verify zero energy. When you are validating zero voltage, we have to regard this as live work. What if you opened the wrong disconnect. That happens all of the time. Perhaps the most important things we preach to our clients is, “Test Before Touch,” and, of course, wear PPE while you’re doing it. Every circuit has to treated as energized until we have proven it is not.

Job Safety Planning

Before a task has begun that will expose workers to electrical hazards, such as our example of adding a circuit breaker to a 480/277 volt panel, a qualified person must create a job safety plan(JSP). The JSP has to include a description of the job and tasks, shock and arc risk assessments, and work procedures, special precautions, and energy controls. Once you have the plan created a job briefing needs to take place. Annex I of 70E has a helpful job briefing and planning checklist.

Approach Boundaries

Your electrical safety training must stress these boundaries, so every qualified fully understands what they mean. Approach boundaries operate as their name implies; as you approach a piece of electrical equipment with exposed energized circuit parts, there is a point at which the risk of injury becomes great enough that additional rules apply. Two shock-protection approach boundaries will be a central part of your shock protection; those are limited and restricted. They each have their own rules. There is also an arc flash boundary that marks where a second-degree burn is likely to occur on bare skin if an arc flash occurs. Each of these boundaries marks a spot where an increase in awareness, blocking access, work permits and PPE are going to be required. These boundaries mark the line where the likelihood of an injury and it’s severity increase. Barricades, an attendant, or tape are needed to identify the first encountered boundary.

The Limited Approach Boundary

The limited approach boundary is a distance from the employee to an exposed energized circuit part within which a shock hazard exists. The typical nominal AC voltages that a maintenance person would be working on of 120, 208, 220, 240, 277, 380, and 480 all have a limited approach boundary of 42 inches. For higher voltages, please refer to the latest edition of 70E. No unqualified person is allowed inside the limited approach boundary unless a qualified person is escorting them. Crossing this invisible boundary triggers the need to establish an electrically safe work condition.

Electrically Safe Work Condition (ESWC)

You have established an ESWC when you have disconnected the equipment, locked and tagged the disconnect, tested to verify an absence of voltage, and, if necessary, temporarily grounded the equipment. The temporary ground is something typically used in circuits above 1000 volts.

Restricted Approach Boundary

This boundary triggers the need to insulate the worker from the exposed circuit parts by utilizing insulated rubber gloves, insulated tools, sleeves, shields, etc. Unqualified workers are not allowed within the restricted boundary or to take any conductive material or tool within this boundary. There is no listed restricted boundary for 120 volts AC, 70E says to avoid contact. You must wear insulated gloves, use insulated tools when contacting live 120-volt circuits. The earlier mentioned voltages of 208, 220, 240, 277, 380, and 480 volts AC have a restricted boundary of 12 inches.

Arc Flash Boundary

This boundary is a distance at which a worker could suffer a 2nd-degree burn in 1 second to exposed bare skin. We must utilize proper PPE for arc flash protection when inside this boundary. The arc flash boundary is independent of the shock protection boundaries. Where your restricted and limited shock boundaries are 12 inches and 42 inches respectively, the arc flash boundary might be 50 feet, or it might be 1 inch.

Shock risk assessment

We have to perform a shock risk assessment, starting with identifying the shock hazard, which in the example of adding the circuit breaker will be 480 volts. We know our limited approach boundary will be 42 inches and the restricted 12. We will need to de-energize the upstream circuit breaker that feeds “Panel A.”

Turning off the main circuit breaker of “Panel-A” de-energizes all of the circuit breakers in “Panel-A,” but it does not de-energize “Panel-A.” A common misconception. The line side, the side of the breaker with the incoming power, normally the top of the breaker, will still have 480 volts even when turned off. A shock and arc flash hazard would still be present. To de-energize “Panel-A”, we will need to go to the upstream circuit breaker that feeds “Panel-A.”

At this point we have every breaker in the panel opened, including the main. We’re not ready to remove the front cover yet because the line side of the main circuit breaker is energized. The line side of the breaker is the incoming power, and a label on the panel indicates it is fed from MDP-3” and off we go to find “MDP-3.”

We go to the upstream main distribution panel “MDP-3” and find a circuit breaker labeled “Panel-A” and open the circuit breaker and put on our lock and tag.

Upon returning to “Panel-A” to begin removing the cover, we must first put up our barricades. The arc flash label indicates that the arc flash boundary for “Panel-A” is 72 inches. The barricades have to be set at least that far from the equipment to prevent workers from wandering into our work area. Instead of using a barricade a second worker can be employed as an attendant to warn others to stop them from approaching too closely. Ideally, use both a barricade and an attendant. If our arc flash boundary was less than the limited approach boundary, which is 42 inches, your barrier could be set as close as 42 inches. Always set the barricade at the first encountered boundary.

You might be thinking we’re not going to need barricades because “Panel-A” is de-energized. “Panel-A” is not de-energized because we haven’t proven it yet. All we know for sure is we have moved the handle on a circuit breaker in the “MDP-3” panel from the on to the off position. You must treat every circuit, wire, panel or piece of equipment as energized until we have proven it isn’t. Always test before touch.

Now, as we are readying ourselves to open the cover of “Panel-A,” we must address what the PPE requirements for this panel are. Part of our job safety plan would be to read the label on the equipment to determine the PPE needed for this panel. We know it is a 480 volt AC panel and we will be crossing the restricted boundary as we verify zero voltage. Therefore Class 00 gloves, which are rated at 500 volts AC, would be needed. They will also be required as we remove the cover as we likely will be within the restricted boundary at that time as well. Many times, as we remove the cover our tools are still in our hands, so we must use insulated tools rated for the voltage.

The tools and gloves have to be inspected daily before each use. In fact, any piece of equipment you use that has insulation, such as power-tool cord, extension cord, meter leads, tools, and the PPE you wear as a garment has to be inspected by you daily before each use. You must remove them from service if they show any sign of damage. The gloves must be electrically tested every six months. As with all PPE, it is essential that they fit the wearer. Don’t make the mistake of buying only one set of gloves for everyone to share. The companies that manufacture or sell gloves have sizing instructions on their websites. Don’t use gloves that are rated for a much higher voltage than you will ever need. If your workers are only going to be working on 480 volts, don’t buy them 1,000-volt gloves.

For arc flash protection we see that “Panel-A” has an incident energy of 13 cal/cm2 with an arc flash boundary of 72 inches.

The Live-Dead-Live Test

We will be performing a “live-dead-live” test. OSHA and 70E require us to verify zero energy at the panel. You must choose an appropriate voltmeter, test it on a known live circuit to verify the meter is functioning correctly. Then, check the circuit we want to work on to ensure it is de-energized, and then retest the meter. If the meter worked properly before and afterward, it was probably working during the test.

Non-Contact Voltage Detector

Non-contact voltage detectors, although very useful for a lot of things, cannot be used for the verification of 0 volts during lockout/tagout. OSHA and 70E both require us to measure the voltage between all phases, that is L1 to L2, L1 to L3, & L2 to L3, and each phase to ground. A non-contact device cannot do that. They work on the principle of capacitive coupling and require a complete current path from your hand holding it through your body to ground.

PPE Required

What Is An Arc Flash

An arc flash occurs during a short circuit in which current flows through an air gap. It could be started by the accidental dropping of a tool, a worker making a connection between an energized conductor and ground or another phase, or with a bad connection in your electrical system. Anytime current is flowing through an air gap it creates tremendous heat that can quickly burn a worker or ignite their clothing. When the initial shorting of the circuit occurs, the current flows through, in this example, a dropped tool. A dropped tool is a sufficient conductive path to cause the short circuit, but it is not a path that can withstand the available fault current. As thousands of amps of current begin to flow through this bad connection, an air gap is created as the tool melts away. The current is now flowing through what is known as plasma, and plasma is a great conductor. As the plasma ball grows, it begins to short out more of the circuit parts. What might have started as a short to ground is now a short circuit of all phase conductors. All of this takes place in milliseconds. The energy from this event is what engineers calculate during an arc flash incident energy analysis. The amount of available fault current, clearing time of circuit breakers and fuses, and other factors determine what this incident energy will be.

Arc Rated Clothing

All arc rated clothing is flame resistant but not all flame resistant gear is arc rated. Clothes made for flash fire, for use in the petrochemical industry, for example,  are flame resistant but not arc rated. Electrical workers must have arc-rated clothing.

On the label of arc rated gear, it will have an Arc Thermal Protection Value (ATPV) or an Energy Breakopen Threshold (EBT). ATPV and EBT are both evaluated in the same test, ASTM F1959. The first one to be reached is the reported arc rating. To the end user, it just doesn’t matter which it has. One is not better than the other. The thing you want off the label is the incident energy value or the Category number, regardless if it is ATPV or EBT.

Two Methods For Determining The Arc Rated Clothing Needed

The two methods are the Incident Energy Method and the PPE Category Method. Arc-rated clothing is labeled with both because the manufacturer doesn’t know which you will be using.

You must use one or the other, and you can’t mix them on the same piece of equipment. That is you can’t have equipment with an arc flash label that says it has 19 cal/cm2 incident energy and call it a category two panel. If you have the incident energy on the panel it means you have done an arc flash incident energy analysis and your panel is a 19 cal/cm2 panel and the clothing system worn while exposed will need to have a minimum value of 19 cal/cm2. The clothing category doesn’t play into it at all.

Incident Energy Analysis

This method is one in which electrical engineers have calculated an arc flash energy for your panels based on real data collected from the field. It is typically thought to be the more accurate method, although, because of many factors, predicting arc flash energy is not an exact science. The engineers are relying on your over-current protective devices, your fuses and circuit breakers, to operate as designed. The people collecting the real data from your facility have no way of knowing if the circuit breakers have been appropriately maintained over the many years of operation.

PPE Category Method

This method uses a set of tables to determine what the estimated arc flash energy and arc flash boundary are going to be. This method does not use real-world field data from your facility. It estimates all panels of a particular type to be the same no matter what facility they’re in. To use these tables, you must know the kind of equipment, voltage, clearing time of the over-current protective device, and the maximum available fault current. Finding the voltage and equipment type is easy. Clearing time and fault current are going to require electrical engineers to get involved. The data that will need to be collected, such as wire length, wire size, transformer data, and the calculations the engineers will have to make to arrive at your clearing time and available fault current is essentially the same for doing a full incident energy analysis.

For years many employers have used the tables and ignored the requirements for knowing the clearing time and available current.

When to wear PPE

We are required to use Table 130.5 in 70E 2018 for estimating the likelihood of an arc flash event in the equipment that we will be servicing. The table lists equipment and tasks and indicates the likelihood that an arc flash might occur.  This table gives specific tasks, such as Thermography and visual inspections, a pass and says during these tasks there isn’t a likelihood of an arc flash. And further protective measures are not required, including PPE. It also states there are times when the equipment is in the “Normal Operating Condition” that there won’t be a likelihood of an arc flash. Myself, some colleagues in the field, and many of my clients are ignoring this. In our opinion, if the equipment has an arc flash incident energy of 1.2 or above, and you are within the arc flash boundary, PPE should be a requirement no matter what you are doing. And, if an employee is interacting with the equipment, even if the equipment is closed, such as opening or closing breakers, PPE will be utilized. The “Normal Operating Condition” includes a requirement that the equipment is properly maintained and has been used in accordance with the manufacturers’ instructions. How would any employer be able to verify that on a piece of equipment that has been around for many years? In my opinion, you should utilize arc flash PPE indicated by the equipment label any time the equipment doors are open, and you are within the arc flash boundary, and anytime you are interacting with the equipment even if doors are closed.

Your arc flash training needs to include when your facility requires arc flash PPE.

We see the equipment label on “Panel-A” indicates 13 cal/cm2 of incident energy which requires us to wear PPE of at least that arc rating. From table 130.5(G) we see we will need a face shield, hard-hat, balaclava, hearing protection, safety glasses, leather footwear, and because we’ll be within the restricted approach boundary, insulated gloves with leather protectors. We must ensure we aren’t wearing any conductive jewelry and that our undergarments are made of non-melting fabric. The t-shirt you wear under your arc rated clothing has to be made of natural fibers such as cotton. They make arc rated long and short sleeve t-shirts which are ideal for use as an undergarment.

You need to make it clear during your arc flash training, what your PPE procedures are. Does everyone get their own hard-hat, face-shield, and balaclava? Are we using arc rated PPE that we rent or do we own it? Do the employees have to launder it at home and what are those laundering instructions. What about arc flash suits for the high incident energy levels. Where are they kept? One size doesn’t fit all. If one worker is 6 ft 4 inches tall and weighs 250 pounds is going to wear the same arc flash suit as another worker who is 5 foot 7 inches and weighs 130 pounds. No, that won’t work. When a worker is going to exposed to energized work as during verification of zero energy they need to be fully aware of what to wear and where to find it and be comfortable in the knowledge that it is going to be appropriate for their body.

Resources for more information on PPE

Salisbury , Westex, Bulwark, Ariat, Oberon

Your Training

As I’ve said, the employer must provide electrical safe work practices, practices like those in 70E, and then train employees on them. That training needs to be a classroom, instructor-led training that encourages and answers questions. A test of some type and a certificate of completion. Online training should only be used as a refresher course. Your electrically qualified need to be retrained at least every three years.

Document when the training occurred, who was in attendance, and who the instructor was. The contents of this electrical safety training must be documented for future OSHA visits or company safety audits.

Our NFPA70E/Arc Flash Training

Summary

Electrical safety is quite simple. The employer provides safe work practices, trains the employee, and the employee follows them. The employer as well must follow these practices and insist workers priority will always be de-energizing the equipment. The employer also needs to provide proper PPE for the tasks involved. Hopefully, the only energized work, anyone, does at your facility is verification of zero energy during lockout tagout.

This Practical Guide To Arc Flash and NFPA 70E does not cover every detail of the 70E standard. But, hopefully, it will help simplify the standard for those using it in the field.

1. Provide electrical safe work practices.
2. The centerpiece of those work practices must be the elimination of the hazard. Establishing an Electrically Safe Work Condition.
3. Train your people on those work practices. Your electrical safety training, arc flash training is the glue that holds your electrical safety program together.
4. Ensure your employees are qualified for the electrical tasks they are about to perform and the hazards for which they are exposed.
5. Provide proper PPE for the hazards your people will face. Make sure that PPE fits the individual.
6. A qualified worker must conduct a job safety plan and there must be a job briefing prior to work beginning.
7. Conduct proper risk assessments prior to work beginning.

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This new one-hour online 70E for managers class covers those things that a manager needs to know to effectively manage an electrical safety program. If your direct reports include electrically qualified workers this class can help you comply and create a safer working environment. We’ll cover the topics that managers and safety professionals have to be diligent about when managing workers around electrical hazards.

Link to Online 70E For Managers

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Course Description:

This course is approximately 2-hours with a timed test at the end. A certificate is given upon successful completion.

What You Will Get Out Of This Course
Workers taking this 2-hour online refresher course will learn the latest in electrical safety standards and regulations. This training goes toward satisfying your OSHA training requirement and will produce workers more aware of the hazards and how to reduce the risk. This course reflects the evolution of NFPA 70E in the direction of risk assessment and hazard elimination. The hierarchy of risk control, shock and arc flash hazard PPE selection are covered in detail. OSHA 1910, as well as NFPA 70E 2018 edition, will be discussed. This course is a refresher course for people who have previously attended instructor-led, full-day, classroom 70E training. Your people will walk out of this class better prepared for work involving electrical hazards.

More Information – Online Refresher

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Watch for next years conference February 26-28, 2019.

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This is meant to serve as a snapshot of important 70E topics.

Work De-energized

Electrically Safe Work Condition

“Live-Dead-Live” Test

Qualified For The Task

Demonstrate Qualification

Energized Electrical Work Permit

Assess Risk Before Work Begins

Shock Risk Assessment

Arc flash Risk Assessment

Hierarchy of Risk Control

Arc Flash PPE Category Method

Incident Energy Analysis Method

Equipment Labeling

Electrical Safety Training

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