Write a toolbox talk on arc flash

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# Protection from Electric Shock and Arc Flash Journeyman Technical Information Paper 2 OBED LEB 10 1808 BAITDING-C REHICYA FEDEBLOW ROBAR About 50 electrical workers are killed in construction every year in the U.S. by electric current and many more are injured. Over half of the deaths are from working on energized ("live") electric circuits without proper protection - often when it was not necessary to work "live." At least one-third of the electrocutions occur at low voltage, under 600 volts. This paper discusses precautions for electricians, but does not cover electric utility work. ## Electric hazards Electricity-related hazards include electric shock and burns, arc-flash burns, arc-blast impacts, and falls. - Electric shock and burns. An electric shock occurs when electric current passes through your body. This can happen when you touch an energized part. If the electric current passes across the chest or head, you can be killed. At high voltages, severe burns can result. - Arc-flash burns. An electric arc flash can occur if a conductive object gets too close to a high-amp current source or by equipment failure (for instance, while opening or closing disconnects). The arc can heat the air to temperatures as high as 35,000° F, and vaporize metal in the equipment. The arc flash can cause severe skin burns by direct heat exposure and by igniting clothing. - Arc-blast impacts. The heating of the air and vaporization of metal creates a pressure wave that can damage hearing and cause memory loss (from concussion) and other injuries. Flying metal parts are also a hazard. - Falls. Electric shocks and arc blasts can cause falls, especially from ladders or unguarded scaffolding. ## Electric Safety Principles Plan every job. Decide on your approach and step-by-step procedures. Write down first-time procedures. Discuss hazards and procedures in a job briefing with your supervisor and other workers before starting a job. Your employer should already have or dev…

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# Arc Flash (cont.) ## What elements should be considered when doing an arc flash risk assessment? (cont.) Whenever possible, do not work on energized equipment. Always follow lockout/tagout procedures as part of a hazardous energy control program. Other protective measures include: - Making sure conductors and circuit parts are in a safe working condition - Using lower energy equipment or current energy limiting devices - Guarding energized electrical conductors and circuit parts - Using arc flash approach boundaries, including barricades - Increasing the working distance - Using non-contact instruments or procedures, where possible - Using non-sparking tools - Implementing work permits, safe work procedures, and job planning - Posting signs alerting of the hazards - Wearing shock and arc flash personal protective equipment (PPE) ## What would be included in preventive maintenance? Preventive maintenance includes: - Regular inspection for wear and tear of insulation, corrosion, poor connections, overheated electrical conductors, excessive pitting of contacts, or excessive moisture, water, or ice on the equipment. - Regular measurements of critical components. - Routine inspections of circuit breakers and relays (develop a testing schedule based on the manufacturer's instructions or the InterNational Electrical Testing Association (NETA) guidelines). - Follow established maintenance requirements, including a parts replacement schedule. - Keep electrical drawings current. ## What are approach boundaries? Boundaries are used to limit how close workers and others should be to the equipment or circuits, especially when work is being done. Arc Flash CCOHS

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# Arc Flash (cont.) ## What are approach boundaries? (cont.) Important to arc flash boundaries is the role of qualified persons. A qualified person is someone who has been trained in and has knowledge about the construction and operation of the equipment or work methods. They must be familiar with appropriate techniques, policies and procedures, work permits, PPE, insulating and shielding materials, insulated tools, test equipment, etc. For example, unqualified workers should remain a distance away from the exposed energized conductors or circuit parts (including any equipment or objects they may handle). They should not cross into the arc flash boundary unless they are wearing appropriate PPE and are supervised by a qualified person. At no time should an unqualified person enter the restricted approach boundary. Qualified person may enter the restricted space provided any necessary work permits, PPE, tools, equipment, and measures necessary to reduce the likelihood of contact are taken. ## How is arc flash personal protective equipment (PPE) chosen? Workers must know how to select, use, and care for the necessary PPE, and understand the limitations of the PPE. The CSA standard Z462:21 "Workplace Electrical Safety" provides two methods that can be used to determine what type of PPE is required for a specific job: 1. The incident energy analysis 2. The arc flash PPE category While either method can be used, only one method should be used at a time when working on the same piece of equipment (not both). The first method, incident energy analysis, is based on the distance between the worker's face and chest to the source. It uses the value of the estimated energy of the flash to determine the level of protection that must be provided by the PPE. The second method, arc flash PPE category method, uses the arc flash risk assessment of the tasks and equipment condition to determine if arc flash-rated PPE is required. Once determined that arc flash PPE is require…

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# ARC FLASH HAZARDS (cont.) ## HOW CAN YOU PROTECT YOURSELF FROM THE HAZARDS OF ARC FLASH? (cont.) • De-energizing would create a more significant hazard, or it is necessary for the interests of health and safety that the electrical work is carried out while the equipment is energized (e.g., it may be required for life-saving equipment to remain energized and operating while electrical work is carried out on the equipment). • It is necessary that the electrical equipment to be worked on is energized for the work to be carried out correctly. • It is necessary for testing or troubleshooting. • There is no reasonable alternative means of carrying out the work. ## NOTE: USE APPROPRIATE LOCKOUT, TAGOUT, AND HAZARDOUS ENERGY CONTROL PROCEDURES TO ISOLATE ENERGIZED EQUIPMENT WHEN A CIRCUIT BREAKER OR OTHER DISCONNECT TURNED OFF. THE BEST ARC FLASH PROTECTION IS TO DE-ENERGIZE EQUIPMENT BEFORE WORKING ON IT! IS Second Best Choice for Arc Flash Protection: Use appropriately rated personal protective equipment (PPE). Arc flash personal protective equipment (PPE) is a combination of clothing and safety equipment worn for protection from arc flash and shock hazards by a person performing electrical work. Primarily, arc flash PPE is divided into the following subgroups: • Head, face, neck, and chin protection • Eye protection • Hearing protection • Body protection • Hand and arm protection • Foot and leg protection ## GENERAL ELECTRICAL SAFE WORK PRACTICES All employees working on or near electrical equipment shall follow general safe work practices, including: • Maintain housekeeping procedures in the work area, e.g., prevent slip trips and falls; eliminate fire hazards; control dust; prevent falling hazards; clear clutter. • Plan and analyze each step of a work task to ensure safety. • - Maintain appropriate work boundaries for qualified electrical workers (QEW) and unqualified workers. • Use properly rated and tested test equipment (e.g., multimeter). …

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# De-Energizing (cont.) ## Approach distances to exposed live parts (cont.) represented only by the standard in its entirety. (c) Be certain that no part of the body enters the prohibited space. (d) Minimize the risk from unintended movement, by keeping as much of the body as possible out of the restricted space; body parts in the restricted space should be protected. - The prohibited approach boundary is the minimum approach distance to exposed live parts to prevent flashover or arcing. Approaching any closer is comparable to making direct contact with a live part. To cross the prohibited approach boundary, the qualified person must: (a) Have specified training to work on exposed live parts. (b) Have a documented plan with proper written work procedures and justifying the need to work that close. (c) Do a written risk analysis. (d) Have (b) and (c) approved by the manager responsible for the safety plan. (e) Use PPE appropriate for working near exposed live parts and rated for the voltage and energy level involved. Arc flash. The flash protection boundary is the distance at which PPE is needed to prevent incurable burns (2nd degree or worse) if an arc flash occurs. (You still can get 1st or 2nd degree burns.) For systems of 600 volts and less, the flash protection boundary is 4 feet, based on an available bolted fault current of 50 kA (kiloamps) and a clearing time of 6 cycles (0.1 seconds) for the circuit breaker to act, or any combination of fault currents and clearing times not exceeding 300 kA cycles. For other fault currents and clearing times, see NFPA 70E. Remember, when you have de-energized the parts you are going to work on, but are still inside the flash protection boundary for nearby live exposed parts: If the parts cannot be de-energized, you must use barriers such as insulated blankets to protect against accidental contact or you must wear proper PPE. ## Proper Personal Protective Equipment When working on or around live circuits, be s…

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# Arc Flash (cont.) ## What are the hazards related to arc flash? (cont.) An arc flash may be caused by many factors or events, such as: - Unintentional tool contact with live parts - A tool dropped on the ground, which creates a spark which starts an arc discharge - Equipment failure due to poor maintenance or improper design - Use of tools that spark - Corrosion of contact surfaces - Loose contacts - Worn or damaged insulation - Dust and condensation on the insulating materials (The dust or moisture provide a path for the electrical current and can lead to flashovers that create an arc discharge) - Incorrect installation of conductors, such as when conductors of different phases are installed too close - Incorrect installation of arc-resistant equipment - Incorrect work procedures. The possibility of an arc flash increases when there are exposed energized electrical conductors or circuit parts; or when safe work procedures are not followed. ## What elements should be considered when doing an arc flash risk assessment? An arc flash risk assessment should be done to: - identify arc flash hazards - determine the likelihood of an arc flash, and the injuries it may cause - determine the severity of the injuries - determine what protective measures are needed, including personal protective equipment (PPE) When estimating the likelihood and severity of the event, consider factors such as the design of the electrical equipment, the presence of an overcurrent protective device, and operating time. Also important is the condition of the electrical equipment, and the effectiveness of any maintenance activities. What are some protective measures that can be taken? Arc Flash CCOHS

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# Arc Flash (cont.) ## What are approach boundaries? (cont.) An arc flash boundary is the term used to describe the distance at which a person without personal protective equipment (PPE) may get a second-degree burn if an arc flash occurs. It is assumed that a second-degree burn occurs when the incident energy received by the skin equals 5 J/cm2 (1.2 cal/cm2). A second-degree burn is usually treatable. There are two types of boundaries that are used: - Limited approach boundary - the distance from an exposed energized electrical conductor or circuit part a person may approach when a shock hazard exits (i.e., if the person is wearing appropriate PPE and are supervised by a qualified person). - Restricted approach boundary - the distance from an exposed energized electrical conductor or circuit part a qualified person (only) may approach when there is an increased likelihood of electric shock due to electrical arc over combined with inadvertent movement. Flash boundary Limited approach boundary Restricted approach boundary Any exposed and energized conductor or circuit part The distance of the boundaries will vary, and depend on: - the system present (alternating-current or direct-current systems) - the voltage range (phase to phase) or the nominal potential difference - the presence of equipment including fuses, relays, circuit breakers, exposed movable conductors or fixed circuit parts - the use of devices to restrict inadvertent movement Arc Flash CCOHS

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# An Electrician and an Electrical Helper Burned During Arc Flash Explosions February 2006 Burn Injury Narrative SHARP Report # 85-1-2006 A journeyman electrician and an electrical helper were at a worksite to install a new three-phase run of wire between an existing energized 480-volt circuit breaker panel and a new piece of machinery. During the process, the journeyman electrician attempted to install a missing bolt from a breaker mount on an energized 480-volt bus bar. The electrician used protective insulating gloves, but did not use safety glasses, shields, or any other safety equipment. While attempting to screw the bolt into place, he lost control of the bolt. Either the bolt or the mount (or both) then contacted another phase in the circuit breaker panel resulting in an arc flash. The electrician temporarily lost his sight and received first and second degree burns to his head, face, and forearm. A few minutes later, the helper was demonstrating to the facility owner what had happened, when a second electrical arc flash occurred at the breaker panel. The cause of the second arc flash is not known. The helper received second-degree burns to his head, face, neck, arm, and hand. The nylon jacket he was wearing melted to his skin. He was not wearing any personal protective equipment. The helper had no formal electrical training. The electrician was hospitalized for one day while the helper required multiple hospital visits to treat his burns. Injuries such as these may be prevented by taking the following steps: • Electrical systems should be worked on in a de-energized state. - Discuss with the site manager whether the required work could be performed de- energized. This can often be accomplished through pre-planning and scheduling. - Isolate and lockout energy sources. Ensure that stored energy does not exist and apply appropriate grounding if necessary. - Use properly rated voltage testers to verify the absence of voltage at each energy point.…

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# MIOSHA Fact Sheet # Electrical Shock Hazards MIOSHA Michigan Occupational Safety and Health Administration ## How does electrical shock injure someone? Body contact with an electric power source can result in burns, systemic shock, neurological damage, and ventricular fibrillation in the heart. Electricity always follows the shortest circuit and path of least resistance. If a human body provides that path, electricity will flow to ground or complete a circuit through the body. Death caused by electrical shock is referred to as electrocution. Fatal electrical shocks can even happen to people who should know better or have worked a long time with electrical equipment and become over-confident. People have been killed by 120 volts AC in the home and with as little as 42 volts DC because sufficient current is generated at these low voltages to cause fatal injury. The minimum current a human can feel is thought to be about 1 milliampere (mA). Currents approaching 100 mA may be lethal. ## What are some common reasons people suffer electric shock injuries or fatalities? • Body contact with overhead power lines • Faulty insulation • Improper grounding of equipment • Loose connections or defective parts • Ground faults in equipment • Unguarded live (electric) parts • Failure to de-energize electrical equipment when it is being repaired or inspected • Use of defective and/or unsafe tools • Use of tools or equipment too close to energized parts resulting in arc flash ## What is arc flash? Arc flash is a short circuit through air that flashes over from one exposed live conductor to another conductor or to ground. An arc blast is the pressure wave. Arc flash can cause serious burns or electrocution. According to the National Fire Protection Association Standard (NFPA) 70E-2004, most burn hospital admissions due to electrical accidents are from arc flash burns, not from electrical shock. A report compiled by Capelli-Schellpfeffer, Inc., estimates that five to …

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# Arc Flash Results in Dual Injuries March 2006 Burn Injury Narrative SHARP Report # 85-2-2006 A journeyman electrician with over 25 years of experience and an electrical apprentice were removing a circuit from a 480 volt, 600 amp main breaker panelboard in the electrical room of a large public building. The breaker which supplied power to the entire building was in the off position; however, the conductors into the top of the breaker were still energized. The journeyman was in the process of removing a circuit from the upper left hand side of the enclosure. The apprentice was standing on a ladder 4 to 5 feet to the left and was manually supporting the conduit that held the circuit wires. The ground wire being removed was still connected at its other terminal. Electrical tape was not used to insulate this wire or the conducting wires. Shielding material was not used to protect the exposed energized conductors entering the main breaker. Apparently, the ground wire contacted the energized terminals on the main circuit breaker. The apprentice witnessed a large flash and loud noise, followed rapidly by two more explosive noises. He then noticed that the synthetic clothing that his work partner was wearing was in flames. The apprentice patted out the flames on his partner with his hands and burned himself in the process. He then led the journeyman electrician out of the smoke filled room and notified 911. The journeyman sustained second and third degree burns covering nearly 50% of his body. He required surgery for removal of destroyed skin and restorative skin grafts. He needed physical therapy for nearly a year. He returned to work after several months and to full time after about a year. The apprentice was treated for second degree burns. Injuries such as these may be prevented by taking the following steps: . Establish an electrically safe work condition whenever possible. This includes the de- energizing, lockout/tagging of disconnecting devices, grounding t…

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# De-Energizing (cont.) ## Table 2. Hazard risk category classification (within flash protection boundary) (cont.) Table 3. Simplified, two-category, flame-resistant clothing system <table><tr><th>Applicable tasks</th><th>Clothing requirement</th></tr><tr><td>All hazard/risk category 1 and 2 tasks listed in table 2 On systems operating at less than 1000 volts, these tasks include work on all equipment except Insertion/removal of low-voltage motor starter “buckets" Insertion/removal of power circuit breakers with the switchgear doors open Removal of bolted covers from switchgear. On systems operating at 1000 volts or more, tasks also include the operation, insertion, or removal of switching devices with equipment enclosure doors closed.</td><td>Everyday work clothing Flame-resistant long-sleeve shirt (minimum ATPV of 5) worn over an untreated cotton T-shirt with FR pants (minimum ATPV of 8) Or FR coveralls (minimum ATPV of 5) worn over an untreated cotton T-shirt (or an untreated natural-fiber long- sleeve shirt) with untreated natural- fiber pants.</td></tr><tr><td>All hazard/risk category 3 and 4 tasks listed in table 2 On systems operating at 1000 volts or more, these tasks include work on energized parts of all equipment. On systems of less than 1000 volts, tasks include insertion or removal of low-voltage motor-start motor control center “buckets," insertion or removal of power circuit breakers with the switchgear enclosure doors open, and removal of bolted covers from switchgear.</td><td>Electric "switching" clothing Double-layer FR flash jacket and FR bib overalls worn over either FR coveralls (minimum ATPV of 5) or FR long-sleeve shirt and FR pants (minimum ATPV of 5) worn over untreated natural-fiber long-sleeve shirt and pants worn over an untreated cotton T-shirt Or Insulated FR coveralls (minimum ATPV of 25, independent of other layers) worn over untreated natural- fiber long-sleeve shirt with untreated cotton blue jeans ("regular weight," minimum 12 o…