1. External Operating Experience Update: Arc Flash Safety
Department of Energy
Operating Experience Work Group
December 12, 2017
Larry Stirling
Office of Analysis (AU-23)

2. Overview Definition Causes Hazards Controls Special Considerations
Incidents at DOE
Resources

3. What is an arc flash?
Electrical current flows through an air gap between conductors
causes a burst of intense heat and light
An arc flash occurs when electrical current flows through an air gap between conductors, causing a burst on intense heat and light, which can seriously injure workers who are exposed to the arc. In an arc flash, the electrical current uses air as a conductor, exploding from a high voltage source to another conductor or ground nearby

4. Causes
Voltage transients (spikes) resulting from switching reactive loads
Touching a test probe to the wrong surface
Slipped tool
Overloading/overheating circuits
Over-fusing
Arc flash accidents are most frequently caused by voltage transients (spikes) resulting from switching reactive loads, touching a test probe to the wrong surface, or a slipped tool. They can also be caused by overloading/overheating circuits, or over-fusing.
A reactive load is a load which is carried by an alternating current generating station or system in which the current and voltage are out of phase and which is measured in volt-amperes or kilovolt-amperes

5. Causes Sparks due to breaks or gaps in the insulation
Equipment failure, due to
use of substandard parts
improper installation
normal wear and tear
Dust, corrosion, condensation, or impurities on surface of conductor
Arc flashes can also be caused by sparks due to breaks or gaps in the insulation, equipment failure due to the use of substandard parts, improper installation, or even normal wear and tear, or dust, corrosion or other impurities on the surface of the conductor.

6. Hazards Electricity  shocks, electrocution Heat  burns, fire
Potentially fatal
Heat  burns, fire
Up to 35,000°F
Light  eye injuries
Sound  hearing loss
The electrical current itself can cause shocks or electrocution.
The heat from the flash can cause severe burns. It can be up to 35,000 degrees Fahrenheit, which is hotter than the surface of the sun. Each year more than 2,000 people are treated in burn centers with severe arc flash injuries. Fatal burns can occur when the victim is several feet from the arc. Serious burns are common at a distance of 10 feet.
The light is UV and IR and can damage the eye, resulting in temporary or permanent blindness, or the later development of cataracts.
The sound pressure of an arc flash can rupture eardrums. The sound associated with the blast can greatly exceed the sound of a jet engine.

7. Hazards
Arc blast: a supersonic shockwave produced when an uncontrolled arc vaporizes the metal conductors
2,000 lbs./square foot blast pressure
Can damage hearing, lung and brain function
Can knock workers off their feet or elevated work surface
Can send loose equipment, tools, machinery, and debris flying to cause further injuries
Potentially fatal
READ SLIDE. The arc blast results from an explosive change in state from solid to vapor. Copper vapor expands to 67,000 times the volume of solid copper, producing a supersonic shockwave. It can produce 2,000 lbs/square foot blast pressure, which can damage hearing, lung and brain function. The arc blast can knock workers off their feet or elevated work surface, and send loose equipment, tools, machinery, and debris flying to cause further injuries from this shrapnel. The arc blast is potentially fatal. In some cases, the pressure wave has sufficient energy to snap the heads of 3/8-inch steel bolts and to knock over construction walls.

8. Hazards Severity determined by Voltage
Proximity of the worker to the hazard
Temperature
Time for circuit to break
Grounding
Gap between conductors
The severity of the effects of an arc flash is determined by… READ SLIDE.

9. Controls Arc Flash Study
Performed on each piece of equipment operating at 50 volts or more and not put into a de-energized state must be evaluated for arc flash and shock protection.
Software available to assist
Qualified professional engineer
Results
arc flash boundaries
PPE requirements
In order to identify the specific arc flash hazard at a given piece of equipment within a facility, an arc flash study must be performed. There are several software packages available, similarly to short circuit study and coordination study software packages, to facilitate this analysis by a qualified professional electrical engineer. In order to perform the arc flash study a short circuit and coordination study must first be performed or the results of these studies must be available to the engineer performing the arc flash study.

10. Controls Arc Flash Protection Boundary
Arc flash boundaries are imaginary lines, like those pictured here, that are determined from the arc flash study.
The boundaries must be calculated by a qualified safety engineer using the data and formula contained in NFPA 70 and NFPA 70E, and based on the voltage of the equipment. The arc flash boundary around exposed equipment varies according to voltage and distance from the exposed parts.
The arc flash protection boundary (FPB) is the minimum ‘safe’ distance from energized equipment that has a potential for an arc fault. It is defined as the distance at which, in the event of an arc flash, a worker would be exposed to a thermal event with incident energy of 1.2 cal/ cm² for 0.1 second. With this exposure, a worker may receive a 2nd degree burn to exposed skin. If it is necessary for workers to cross the flash protection boundary, and potentially be exposed to higher incident energies from any arc flash, they must be wearing appropriate PPE.
The limited approach boundary
This is the minimum permitted distance that unqualified and unprotected personnel may approach a live component. Before crossing the limited approach boundary and entering the limited space, a suitably qualified person must use the appropriate PPE and be trained to perform the required work. An unqualified person may enter the limited approach area if they are under the supervision of a qualified person. At this boundary, a shock hazard exists.
The restricted boundary
To cross the restricted boundary and access the restricted space, personnel need to have been trained in shock protection techniques, be wearing the correct PPE and have a written and approved plan for any work in the zone. The plan must make it clear that the worker must not enter the prohibited space or cross the prohibited boundary either personally or by using any equipment or tool.
Prohibited boundary
In terms of safety, any worker crossing this boundary must be equipped and protected as they would be for making direct contact with the exposed live equipment. Establishing these boundaries is an important step in protecting staff from the dangers of electrocution. No worker should cross the prohibited boundary and enter the prohibited area unless:
The responsible authority has carried out a full risk assessment.
The work has been documented and it has been fully established why it must be carried it out on live equipment.
The qualified worker has been trained to work on live electrical equipment, and
The worker has been equipped with appropriate PPE.

11. Controls Prevention Training  qualified persons Work planning
Alert non-qualified persons to dangers and use signage/barricades to prevent access into FPB
Work planning
Define responsibilities
Permitting
Pre-job briefing
Control of the work environment
De-energize the circuit and LO/TO
Guarding/barricades
Grounding (secondary protection)
Qualified persons must have received training in and demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved. At a minimum, qualified persons must be trained in and familiar with
The skills and techniques necessary to distinguish exposed live parts from other parts of electric equipment.
The skills and techniques necessary to determine the nominal voltage of exposed live parts, and
The clearance distances specified in (c) and the corresponding voltages to which the qualified person will be exposed
Work planning must include SMEs, must define responsibilities for each individual and clearly communicate who will perform zero-energy checks and how. If it is impossible to de-energize equipment, permitting procedures must be strictly controlled. A pre-job briefing is useful for communicating the work plan, identifying the hazards and controls, and inviting feedback and questions to help identify any unforeseen risks. The workers who are involved have an important perspective to share.
Controlling the work environment can be done by using guarding, barricades, and signage. De-energizing the equipment and locking and tagging it out is the safest option. Grounding is a secondary means of protection.

12. Controls Tool Selection
Flame retardant
Double insulated
Removed from service if any signs of wear and tear
Rated to 1,000 v
Correct tool selection is necessary for protection against arc flash hazards. Tools must be flame retardant, double insulated, and rated to 1,000 volts, which is indicated by the presence of this sign. Remove tools from service if any signs of wear and tear are observed. For example, if the outer insulating layer is worn, and the second layer of insulation can be seen, the tool must be removed from service.

13. Controls Personal Protective Equipment
Shirts
Pants
Undergarments
Goggles
Gloves
Hard hats
Shields- face/neck
Shoes
The main objective of the PPE is to limit the burns to the body resulting from an arc flash event, to a survivable level. (i.e .2nd degree or less). PPE is determined from the arc flash study.

14. Special Considerations NRC Information Notice
NRC Information Notice : High Energy Arcing Faults (HEAF) In Electrical Equipment Containing Aluminum Components
HEAF tests involving aluminum resulted in a significantly larger release of energy than HEAF tests involving copper
The presence of aluminum in the components, subcomponents, or parts that form part of the normal current carrying pathway causes a more energetic plasma development when consumed during the arcing process.
The increased energetic plasma causes a larger amount of cabinet damage and/or the transport of gaseous high energy particles/plasma farther than previously assumed.
READ SLIDE

15. Incidents at DOE 2017
September 29, 2017: a small arc occurred during wire pulling; two energized wires found in the panel were connected to a solenoid pH control valve outside the building, which was fed from the pH control unit plugged into a nearby portable generator.
August 3, 2017: electrical arc from a looped wire to the metal of the junction box; investigation indicated that one of the wires was likely nicked in the past during installation.
Since the beginning of 2017, there have been six arc flash occurrences reported into the Occurrence Reporting and Processing System. There have been more than ten incidents of hazardous energy control program violations in which an arc flash could have occurred and caused injury to exposed workers, including incorrect selection of PPE, unexpected discovery of hazardous energy (failure to identify, de-energize and lockout/tagout), and unauthorized employees entering arc flash boundaries. In preceding years, there are many more examples of arc flash occurrences, one of which caused a fatality in These are a few occurrences of incidents this year. READ SLIDE.

16. Incidents at DOE 2017
July 19, 2017: a casting furnace solenoid arc-flashed while manually lowering a furnace pedestal.
May 3, 2017: electrical cabinet opened by an authorized employee to take pictures for a work package being developed to trouble shoot the controls for another identical piece of equipment. No zero-energy verification had been performed. Employee was within the arc flash boundary and limited approach boundaries without the appropriate PPE.
These are some more examples of occurrences this year. READ SLIDE

17. Incidents at DOE 2017
July 18, 2017: When testing capacitors, employee went to attach a safety ground across the capacitor. The capacitor was not safely discharged, and an arc flash occurred when the employee tried to attach the clip lead. Employee received second degree burns on fingers.
May 3, 2017: while performing a Diesel Generator load test, an arc of electrical components occurred in automatic transfer switch (ATS) during the manual transfer from normal power to diesel power. Employee was dressed in a 40 calorie flame-resistant flash suit. Immediately prior to the arc, the ATS began making an unusual buzzing noise and personnel backed away from the switch. There was an evacuation, and no injuries.
…and some more. READ SLIDE
These incidents demonstrate the ongoing need to apply controls, in the context of ISMS, to reduce the likelihood of experiencing a hazardous arc flash.

18. Resources
DOE. Handbook on Electrical Safety. HDBK pdf
DOE. Lessons Learned from 2015 LANL Electrical Arc Flash. learned-2015-lanl-electrical-arc-flash
NRC. NRC Information Notice : High Energy Arcing Faults (HEAF) In Electrical Equipment Containing Aluminum Components
Here are a few resources to learn more. Of course, the DOE Handbook on electrical safety, which is at the first link here.
Please visit the second link, at your convenience, to learn about an arc flash that occurred in 2015 at LANL, and gain valuable lessons learned from the incident. It is an excellent corollary to this slideshow.
The NRC Information notice was cited in the this presentation, and includes several examples of arc faults at nuclear power plants and stations.

19. Resources
US Navy. Workplace Safety Awareness Council. Understanding “Arc Flash” PDF /OSH/training/arc_flash_handout.pdf
OSHA. Workplace Safety Awareness Council. Train- the-Trainer Guide to Electrical Safety for General Industry /train-the-trainer_manual2.pdf
Here are some more resources: one from the Navy, and one from OSHA, which are training manuals on arc flash safety.

20. Resources
NFPA. Codes and Standards. and-standards/list-of-codes-and- standards/detail?code=70E
IEEE IEEE Guide for Performing Arc Flash Hazard Calculations.
The first link is to the NFPA website, where codes and standards can be accessed or purchased, including NFPA70 and NFPA 70E. The second link is the guide to performing arc flash hazard calculations.

21. Resources
CDC. NIOSH. Arc Flash Awareness: Information and Discussion Topics for Electrical Workers oducts/videos/arcflash/afa.pdf
NIOSH. Arc Flash Awareness Video.
Murray State University. Presentation on Arc Flash Safety ation%20-%20Arc%20Flash%20Safety.ppt
Here are some more educational resources; two from NIOSH, one of which is a 25 minutes video on arc flash, and one from Murray State University, which is a powerpoint presentation on arc flash safety.

22. Contact Information
Larry Stirling Office of Analysis (AU-23)