This webinar reviews arc flash and the precautions to take to prevent it.
Attendance will be taken. Please hold all questions until the end of the
presentation.
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This presentation will be beneficial to maintenance and facility personnel,
technicians, authorized lockout/tagout personnel, electrical safety program
managers, safety and health professionals, and arc flash qualified persons.
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Arc flash hazard: A dangerous condition associated with the possible release of
energy caused by an electric arc.
View this video to see an arc flash demonstration at 480 volts:
https://www.youtube.com/watch?v=DFw8t7tG1Y0
Occupations at risk for arc flash exposure include electricians, mechanics,
preparation plant workers, and laborers.
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Examples of a qualified person typically include electricians, electrical engineers,
or trained maintenance technicians.
Qualified persons must be familiar with required personal protective equipment,
insulated tools, exposures to energized electrical conductors and circuit parts,
voltage, and boundary distances.
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Energized: Electrically connected to, or is, a source of voltage.
An arc flash hazard may exist when energized electrical conductors or circuit
parts are exposed. A hazard may also exist when these conductors or circuit
parts are in a guarded or enclosed position, provided a person is interacting with
the equipment in such a manner that could cause an electric arc.
Condensation, corrosion, and dust may also result in arc flash hazards.
The image on the slide shows an arc blast incident.
Image retrieved from the Department of Labor Employment and Training
Administration at: http://msamc.org/arcflash/Arc_Flash_Overview3.html
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Qualified persons measure the severity of arc flash hazards.
The closer the employee is to the arc flash hazard, the more severe an injury
could be if an arc flash incident occurs.
High temperatures and high humidity result in a more conductive electrical
current, which can create a more severe arc flash incident.
More severe injuries can occur if the employee does not wait long enough for
the electrical source to de-energize prior to performing any testing or
maintenance.
The image on the slide shows a temperature and humidity meter (otherwise
known as a thermohygrometer) – two factors related to the severity of arc flash
incidents.
Images retrieved from CTC.
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Burns may result from exposure to extreme heat during an arc flash event. The
heat can reach 35,000° Fahrenheit. (Occupational Safety and Health
Administration (OSHA): https://www.osha.gov/dte/grant_materials/fy07/sh16615-07/arc_flash_handout.pdf)
Contact with molten metal fragments may occur during an arc flash explosion,
throwing shrapnel through the air. This shrapnel may contact and/or penetrate
nearby workers. The intense light may cause temporary or permanent blindness.
A pressure wave is an area of pressure expanding supersonically outward from
an arc flash explosion. The pressure from a blast wave can affect nearby
workers. It may rupture ear drums, cause hearing loss, knock workers down, or
collapse lungs.
A sound blast is similar to a blast wave. Instead of pressure creating a blast, it is
a loud sound. It frequently accompanies a pressure wave.
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Occupational Safety and Health Administration (OSHA) 29 CFR 1910.333:
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDA
RDS&p_id=9910
National Fire Protection Association (NFPA) 70E: http://www.nfpa.org/codesand-standards/document-information-pages?mode=code&code=70E
Although NFPA 70E is a consensus standard, OSHA requires full compliance
with NFPA 70E and issues citations for non-compliance through the General
Duty Clause. Other OSHA standards in 1910, Subpart S also reference NFPA
70E. NFPA 70E is part of the National Electric Code, Part 70.
NFPA 70E is updated every three years. The most recent update occurred in
2015. The standard issued in 1979 was known as the Standard for Electrical
Safety Requirements for Employee Workplaces. It is now the Standard for
Electrical Safety in the Workplace.
Images retrieved from the NFPA and OSHA at: http://catalog.nfpa.org/NFPA70E-Standard-for-Electrical-Safety-in-the-Workplace-2015-1-day-ClassroomTraining-P16031.aspx?icid=B501
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Live electrical parts: The components that are electrically connected to, or have
a, voltage source.
De-energize electrical sources before performing work. De-energizing each
source will reduce the likelihood and severity of an arc flash incident. Evaluate
each electrical source to determine if the de-energizing process will introduce
additional hazards or increase potential hazards. At times, it may not be feasible
to de-energize all sources due to equipment design or operational limitations.
(OSHA 29 CFR 1910.333(a)(1))
Use an approved multimeter to ensure no electricity is flowing through the
equipment. A qualified person must test equipment to see if it is de-energized.
The image on the left show an employee using a voltage tester to determine the
voltage of the electrical equipment prior to work.
Image retrieved from the Department of Labor Employment and Training
Administration at: http://msamc.org/arcflash/Arc_Flash_Overview22.html
The image on the right shows a clamp multimeter.
Image retrieved from CTC.
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The items listed on the slide include the actions required to comply with
applicable arc flash regulations and guidelines.
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Incident energy: The energy per unit area received on a surface located a
working distance away from the arc flash location.
Working distance: The distance from the worker to the arc flash location.
Incident Energy Equation: E= 4.184CfEn (t/0.2)(610x/Dx) (J/cm2)
Cf = calculation factor on system voltage (1.5 for voltages of 1 kV or less; 1.0 for voltages above 1 kV),
En = normalized incident energy
t = arcing fault duration (in seconds)
D = working distance from the arc source (in millimeters)
x = distance exponent from Table 4 of IEEE 1584
Arc flash risk assessments do not have to be completed if the personal protective requirements of NFPA
70E, 130.7(C)(9)(a) are met instead.
The image shows a qualified employee performing an arc flash risk assessment.
Image retrieved from the Los Alamos National Laboratory at:
www.lanl.gov/safety/electrical/docs/arc_flash_safety.pdf
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A qualified person must complete all arc flash risk assessments.
The image shows qualified persons reviewing information obtained during the
arc flash risk assessment.
Image retrieved from the Department of Labor Employment and Training
Administration at: http://msamc.org/arcflash/Arc_Flash_Overview20.html
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Arc flash boundary: The distance at which the incident energy or the worker
exposure levels equal 5 J/cm2 (1.2 cal/cm2).
Flash protection boundary: The distance to prevent injuries from an arc flash (no
more than a second-degree burn).
Limited approach boundary: An approach limit set at a distance from an exposed
live part, where a shock hazard exists.
Restricted approach boundary: An approach limit set at a distance from an
exposed live part, which there is an increased risk of shock.
Calculate and identify arc flash boundaries utilizing the IEEE 1584 formula or the
NFPA 70E, Table 130.4. You can find several free calculators on the internet to
help calculate these boundaries.
Note: The prohibited approach boundary was eliminated in the NFPA 70E-2015
update.
The image on the slides show the three types of arc flash boundaries, updated
for 2015.
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Image retrieved from the Department of Labor Employment and Training
Administration at: http://msamc.org/arcflash/Arc_Flash_Overview28.html
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Review the written electrical safety program at least every three years (OSHA
and NFPA). The electrical safety program must include provisions directly
related to arc flash hazards.
The DoD requires all hazard control programs to be reviewed annually (DoDI
6055, Section 9). It is a good idea to document these reviews, even if no
changes were made to the program.
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ATPV: The maximum incident energy (cal/cm2) that protective equipment can be
exposed to and prevent second-degree burns.
PPE determination: Based on the incident energy analysis or utilizing the tables
in NFPA 70E 130.7(c)(15)(A)(b) or 130.7(C)(15)(B) and 130.7(c)(16). The table
lists corresponding APTV rating and clothing types.
The American Society for Testing Materials (ASTM) provides guidelines for arcrated apparel, face, gloves (leather protectors and rubber insulating), and
rainwear during electrical work utilization. Eye, face, and head protection need to
adhere to the American National Standards Institute (ANSI) performance
standards.
Additional information on protective clothing requirements:
http://ewh.ieee.org/soc/ias/pcic/archive/Pcicarc1a.PDF
The image on the slide shows an example of arc-rated hand protection. The
gloves are stamped with the maximum use voltage and last inspection date to
allow workers to know the protection level of the gloves.
Images retrieved from CTC.
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All protective clothing and equipment must be arc-rated and labeled by the
manufacturer. In previous releases of the NFPA 70E, the term "flame-resistant"
had been used, but is now removed to clarify that the only acceptable rating that
will be allowed is the arc flash level.
Clothing made from acetate, nylon, polyester, or rayon is prohibited near
energized electrical parts.
Category 1: Used for electrical sources that do not exceed 240 volts.
Category 2: Used for electrical sources no less than 240V and do not exceed
600V.
Category 3: Used for electrical courses that exceed 1 kilovolt through 15
kilovolts.
Category 4: Used for electrical courses that exceed 1 kilovolt through 15
kilovolts.
Note: The category range used to be 0 – 4. NFPA 70E eliminated the 0 category
with the 2015 updates.
See the Department of Labor Employment and Training Administration for more
details: http://msamc.org/arcflash/Arc_Flash_Overview37.html
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The image shows employees wearing the proper PPE as they perform work on
an energized electrical panel.
Image retrieved from the Department of Labor Employment and Training
Administration at: http://msamc.org/arcflash/Arc_Flash_Overview21.html
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The image on the left shows a worker wearing arc-rated protective clothing to
protect himself against arc flash hazards. The image in the corner is a clothing
tag for arc-rated clothing.
The image on the right shows a glove storage bag that allows for flat storage of
gloves to prolong glove life and protect them against damage and deterioration
when not in use. The glove storage bag helps to keep arc-rated gloves separate
from regular work gloves.
Images retrieved from CTC.
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Insulated tool requirements for arc flash are outlined in NFPA 130.7(D)(1).
The image on the screen shows examples of approved insulated tools utilized
for arc flash maintenance.
Image retrieved from OSHA at:
https://www.osha.gov/dte/grant_materials/fy07/sh-1661507/arc_flash_handout.pdf
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Labels are required on electrical equipment that is likely to require examination,
adjustment, servicing, or maintenance while energized. This equipment needs to
be field-marked (directly applied to electrical equipment) with an arc flash label.
(NFPA 70E Section 130.5(D))
There are many versions of arc flash labels, depending on the standard’s time
period the label was issued.
The image on the screen shows an arc flash label on an electrical disconnect
switch.
Image retrieved from the Department of Labor Employment and Training
Administration at: http://msamc.org/arcflash/Arc_Flash_Overview29.html
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The item’s listed on the slide are the elements required under NFPA 70E.
OSHA and the National Electric Code (NEC) both permit the use of basic labels
to inform a worker about a hazard. However, this does not meet the NFPA
standard requirements for providing useful arc flash information.
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The image on the screen shows an arc flash label meeting NFPA 70E
requirements. The label includes the nominal system voltage, the arc flash
boundary distances, incident energy and work distance, required PPE level, and
site-specific level of PPE.
Image retrieved from the Los Alamos National Laboratory at:
www.lanl.gov/safety/electrical/docs/arc_flash_sa
fety.pdf
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The image on the slide shows basic arc flash labels, as permitted by OSHA and
the NEC.
Image retrieved from the Department of Labor Employment and Training
Administration at: http://msamc.org/arcflash/Arc_Flash_Overview29.html
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At a minimum, energized electrical work permits must include:
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Description of the circuit and equipment being worked on
Justification as to why de-energization was not performed
Descriptions of the safe work practices
Results of the arc flash risk assessment
Arc flash protection boundary
Required PPE
Means to restrict access to unqualified persons
Evidence of the required job briefing
Work approval signatures
The image shows an energized electrical work permit.
Image retrieved from the University of Purdue at:
https://www.purdue.edu/rem/home/forms/eewp.doc
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NFPA 110.2(E) requires the employer to document the training received, which
needs to contain name of employee, content of training, and dates of training.
NFPA 130.2(D)(3) requires retraining when:
• Supervision or annual inspections indicate employees are not adhering to
the standards or regulations where arc flash can potentially occur
• There is new equipment or changes to work procedures
• Prior to performing any electrical work that is new to the employee
NFPA 110.2(D) requires retraining every three years, but the employer needs to
verify the employee training is up to date annually (DoDI 6055.01).
The required job briefing must occur before the start of each job and include:
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Electrical hazards associated with the work
Procedures that must be followed when executing the task
Special precautions required for the working conditions, if necessary
Where and how to remove the source of energy
Emergency response and communications
Required PPE
Other work occurring in the immediate area, and
Other work associated with the same electrical circuits
The unqualified person training provides the person with the awareness there is
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potential of an arc flash and the requirements to ensure their safety.
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Several electrical work practices include:
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Be aware of the potential of arc flash
Do not work within the arc flash boundaries while impaired
Be aware of changes in work conditions
Do not reach blindly into areas where there is a potential arc flash hazard
Ensure the area is illuminated adequately and not obstructed
Remove all jewelry or any other conductive articles
Ensure the properly insulated tools are being utilized
OSHA requires the use of alarms to inform the employees there is an arc flash
hazard.
The image on the slide shows barricades. Barricades must not be made of
conductive materials to reduce the hazard of electrical exposure. Use safety
warning signs with barricades to limit access to areas with a potential arc flash
hazard.
Image retrieved from the Department of Labor Employment and Training
Administration at: http://msamc.org/arcflash/Arc_Flash_Overview46.html
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