Make me a 10 minute tool Box Talk focused on safety in electrical construction

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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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# What should I do if I think I am too close to overhead power lines? (cont.) ## What are some general safety tips for working with or near electricity? (cont.) - Be aware that unusually warm or hot outlets or cords may be a sign that unsafe wiring conditions exist. Unplug any cords or extension cords from these outlets and do not use them until a qualified electrician has checked the wiring. - Always use ladders made with non-conductive side rails (e.g., fibreglass) when working with or near electricity or power lines. - Place halogen lights away from combustible materials such as cloths or curtains. Halogen lamps can become very hot and may be a fire hazard. - The risk of electric shock is greater in areas that are wet or damp. Install Ground Fault Circuit Interrupters (GFCIs) as they will interrupt the electrical circuit before a current sufficient to cause death or serious injury occurs. - Use a portable in-line Ground Fault Circuit Interrupter (GFCI) if you are not certain that the receptacle you are plugging your extension cord into is GFCI protected. - Make sure that exposed receptacle boxes are made of non-conductive materials. - Know where the panel and circuit breakers are located in case of an emergency. - Label all circuit breakers and fuse boxes clearly. Each switch should be positively identified as to which outlet or appliance it is for. - Do not use outlets or cords that have exposed wiring. - Do not use portable cord-and-plug connected power tools if the guards are removed. - Do not block access to panels and circuit breakers, or fuse boxes. - Do not touch a person or electrical apparatus in the event of an electrical incident. Always disconnect the power source first. - Make sure electrical tools and equipment have a certification marking from an accredited agency accepted by your jurisdiction (e.g., UL, ULC, CSA, ETL). Be careful when purchasing equipment from another country or online, as they may not be approved. - Make sure…

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CCOHS CCHST Canadian Centre for Occupational Health and Safety Centre canadien d'hygiène et de sécurité au travail Safety Hazards # Arc Flash ## On this page What is an arc flash What are the hazards related to arc flash? What causes an arc flash? What elements should be considered when doing an arc flash risk assessment? What are some protective measures that can be taken? What would be included in preventive maintenance? What are approach boundaries? How is arc flash personal protective equipment (PPE) chosen? What legislation or standards apply to arc flash or electrical safety in the workplace? ## What is an arc flash Arc flash refers to the flash of light and heat that is created when energy is released between a live conductor and another conductor or the ground. During an arc flash, the energy released heats the air to extreme temperatures such as almost 20 000 °C (35 000 °F). At these high temperatures, items within a metre (3 feet) such as clothing and skin will catch fire, melt, or vaporize. In addition, an arc flash will create an arc blast - the heated air expands suddenly and creates a powerful pressure wave (a blast). ## What are the hazards related to arc flash? The heat can cause severe burns which can be fatal. The blast will cause falls and impact injuries. Droplets of melted material and fragments of damaged equipment are spread by the blast at far distances at speeds fast enough for the items to penetrate the body. The pressure wave can also cause damage to hearing or the brain. What causes an arc flash? Arc Flash CCOHS

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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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# Electrical Safety - Basic Information (cont.) ## What do I need to know about electricity? (cont.) Note: Static electricity is the accumulation of charge on surfaces as a result of contact and friction with another surface. This contact/friction causes an accumulation of electrons on one surface and a deficiency of electrons on the other surface. The OSH Answers document on How Do I Work Safely - Static Electricity. has more information. Electric current cannot exist without an unbroken path to and from the conductor. Electricity will form a "path" or "loop". When you plug in a device (e.g., a power tool), the electricity takes the easiest path from the plug-in to the tool and back to the power source. This action is also known as creating or completing an electrical circuit. ## What kinds of injuries result from electrical currents? People are injured when they become part of the electrical circuit. Humans are more conductive than the earth (the ground we stand on) which means if there is no other easy path, electricity will try to flow through our bodies. There are four main types of injuries: electrocution (fatal), electric shock, burns, and secondary injuries (e.g., from a fall). These injuries can happen in various ways: - Direct contact with exposed energized conductors or circuit parts. When electrical current travels through our bodies, it can interfere with the normal electrical signals between the brain and our muscles (e.g., the heart may stop beating properly, breathing may stop, or muscles may spasm). It can also cause burns to internal tissues along the path of the electric current while passing through the body. Burns to external tissues at the entry and exit points of the current can also occur. - When the electricity arcs (jumps, or "arcs") from an exposed energized conductor or circuit part (e.g., overhead power lines) through a gas (such as air) to a person who is grounded (that would provide an alternative route to the ground for the el…

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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