When do I wear arc flash

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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 (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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# 1926.958 MATERIALS HANDLING AND STORAGE (cont.) ## 1926.960(d) Working position. (cont.) - 1926.960(g)(6) Dates. - 1926.960(g)(6)(i) The obligation in paragraph (g)(2) of this section for the employer to make reasonable estimates of incident energy commences January 1, 2015. - 1926.960(g)(6)(ii) The obligation in paragraph (g)(4)(iv) of this section for the employer to ensure that the outer layer of clothing worn by an employee is flame-resistant when the estimated incident heat energy exceeds 2.0 cal/cm2 commences April 1, 2015. 1926.960(g)(6)(iii) The obligation in paragraph (g)(5) of this section for the employer to ensure that each employee exposed to hazards from electric arcs wears the required arc-rated protective equipment commences April 1, 2015. 1926.960(h) Fuse handling. When an employee must install or remove fuses with one or both terminals energized at more than 300 volts, or with exposed parts energized at more than 50 volts, the employer shall ensure that the employee uses tools or gloves rated for the voltage. When an employee installs or removes expulsion-type fuses with one or both terminals energized at more than 300 volts, the employer shall ensure that the employee wears eye protection meeting the requirements of Subpart E of this part, uses a tool rated for the voltage, and is clear of the exhaust path of the fuse barrel. 1926.960(i) Covered (non-insulated) conductors. The requirements of this section that pertain to the hazards of exposed live parts also apply when an employee performs work in proximity to covered (non-insulated) wires. 1926.960(j) Non-current-carrying metal parts. Non-current-carrying metal parts of equipment or devices, such as transformer cases and circuit-breaker housings, shall be treated as energized at the highest voltage to which these parts are exposed, unless the employer inspects the installation and determines that these parts are grounded before employees begin performing the work. - 1926.960(k) Openin…

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# TABLE 7 INCIDENT HEAT ENERGY FOR VARIOUS FAULT CURRENTS, CLEARING TIMES, AND VOLTAGES: LIVE-LINE TOOL EXPOSURES INVOLVING PHASE-TO-GROUND ARCS IN OPEN AIR ONLY * t # # (cont.) ## B. Selecting Protective Clothing and Other Protective Equipment Paragraph (I)(8)(v) of § 1910.269 requires employers, in certain situations, to select protective clothing and other protective equipment with an arc rating that is greater than or equal to the incident heat energy estimated under $ 1910.269(I)(8)(ii). Based on laboratory testing required by ASTM F1506-10a, the expectation is that protective clothing with an arc rating equal to the estimated incident heat energy will be capable of preventing second-degree burn injury to an employee exposed to that incident heat energy from an electric arc. Note that actual electric-arc exposures may be more or less severe than the estimated value because of factors such as arc movement, arc length, arcing from reclosing of the system, secondary fires or explosions, and weather conditions. Additionally, for arc rating based on the fabric's arc thermal performance value 5 (ATPV), a worker exposed to incident energy at the arc rating has a 50-percent chance of just barely receiving a second-degree burn. Therefore, it is possible (although not likely) that an employee will sustain a second-degree (or worse) burn wearing clothing conforming to $ 1910.269(I)(8)(v) under certain circumstances. However, reasonable employer estimates and maintaining appropriate minimum approach distances for employees should limit burns to relatively small burns that just barely extend beyond the epidermis (that is, just barely a second-degree burn). Consequently, protective clothing and other protective equipment meeting $ 1910.269(I)(8)(v) will provide an appropriate degree of protection for an employee exposed to electric-arc hazards. - Paragraph (I)(8)(v) of $ 1910.269 does not require arc-rated protection for exposures of 2 cal/cm2 or less. Untreated cotton cl…

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# Table 1 provides task-based examples of exposure assessments. (cont.) ## Notes: (cont.) Paragraph (g)(5) of $ 1926.960 does not require arc-rated protection for exposures of 2 cal/cm² or less. Untreated cotton clothing will reduce a 2-cal/cm2 exposure below the 1.2- to 1.5-cal/cm² level necessary to cause burn injury, and this material should not ignite at such low heat energy levels. Although $ 1926.960(g)(5) does not require clothing to have an arc rating when exposures are 2 cal/cm² or less, $ 1926.960(g)(4) requires the outer layer of clothing to be flame resistant under certain conditions, even when the estimated incident heat energy is less than 2 cal/cm², as discussed later in this appendix. Additionally, it is especially important to ensure that employees do not wear undergarments made from fabrics listed in the note to 1926.960(g)(3) even when the outer layer is flame resistant or arc rated. These fabrics can melt or ignite easily when an electric arc occurs. Logos and name tags made from non-flame-resistant material can adversely affect the arc rating or the flame-resistant characteristics of arc-rated or flame-resistant clothing. Such logos and name tags may violate 1926.960(g)(3), (g)(4), or (g)(5). Paragraph (g)(5) of $ 1926.960 requires that arc-rated protection cover the employee's entire body, with limited exceptions for the employee's hands, feet, face, and head. Paragraph (g)(5)(i) of 1926.960 provides that arc-rated protection is not necessary for the employee's hands under the following conditions: <table><tr><th>For any estimated incident heat energy</th><th>When the employee is wearing rubber insulating gloves with protectors</th></tr><tr><td>If the estimated incident heat energy does not exceed 14 cal/cm².</td><td>When the employee is wearing heavy-duty leather work gloves with a weight of at least 407 gm/m² (12 oz/yd²)</td></tr></table> Paragraph (g)(5)(ii) of $ 1926.960 provides that arc-rated protection is not necessary for the emplo…

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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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# Emergency repairs to the extent necessary to safeguard the general public. (cont.) ## 1926.960(g)(3). (cont.) paragraph (g)(2) of this section. Note to paragraph (g)(3): This paragraph prohibits clothing made from acetate, nylon, polyester, rayon and polypropylene, either alone or in blends, unless the employer demonstrates that the fabric has been treated to withstand the conditions that may be encountered by the employee or that the employee wears the clothing in such a manner as to eliminate the hazard involved. ## 1926.960(g)(4) Flame-resistant clothing. The employer shall ensure that the outer layer of clothing worn by an employee, except for clothing not required to be arc rated under paragraphs (g)(5)(i) through (g) (5)(v) of this section, is flame resistant under any of the following conditions: ## 1926.960(g)(4).(i). The employee is exposed to contact with energized circuit parts operating at more than 600 volts, ## 1926.960(g).(4)(ii). An electric arc could ignite flammable material in the work area that, in turn, could ignite the employee's clothing, 1926.960(g)(4).(iii). Molten metal or electric arcs from faulted conductors in the work area could ignite the employee's clothing, or Note to paragraph (g)(4)(iii): This paragraph does not apply to conductors that are capable of carrying, without failure, the maximum available fault current for the time the circuit protective devices take to interrupt the fault. 1926.960(g)(4)(iv) The incident heat energy estimated under paragraph (g)(2) of this section exceeds 2.0 cal/cm². - 1926.960(g).(5) Arc rating. The employer shall ensure that each employee exposed to hazards from electric arcs wears protective clothing and other protective equipment with an arc rating greater than or equal to the heat energy estimated under paragraph (g)(2) of this section whenever that estimate exceeds 2.0 cal/cm². This protective equipment shall cover the employee's entire body, except as follows: Submit Feedback

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# Type of insulation. (cont.) ## 1910.269(l)(8)(v)(C) (cont.) exposures involving single-phase arcs in open air or 5 cal/cm² for other exposures, ## 1910.269(l)(8)(v)(D) The protection for the employee's head may consist of head protection meeting $ 1910.135 and a faceshield with a minimum arc rating of 8 cal/cm² if the estimated incident-energy exposure is less than 13 cal/cm² for exposures involving single-phase arcs in open air or 9 cal/cm² for other exposures, and ## 1910.269(l)(8)(v)(E) For exposures involving single-phase arcs in open air, the arc rating for the employee's head and face protection may be 4 cal/cm2 less than the estimated incident energy. Note to paragraph (I)(8): See appendix E to this section for further information on the selection of appropriate protection. 1910.269(l)(8)(vi) Dates. 1910.269(I)(8)(vi)(A) The obligation in paragraph (l)(8)(ii) of this section for the employer to make reasonable estimates of incident energy commences January 1, 2015. 1910.269(I)(8)(vi)(B) The obligation in paragraph (I)(8)(iv)(D) of this section for the employer to ensure that the outer layer of clothing worn by an employee is flame-resistant when the estimated incident heat energy exceeds 2.0 cal/cm² commences April 1, 2015. ## 1910.269(I)(8)(vi)(C) The obligation in paragraph (l)(8)(v) of this section for the employer to ensure that each employee exposed to hazards from electric arcs wears the required arc-rated protective equipment commences April 1, 2015. ## 1910.269(I)(9) Fuse handling. When an employee must install or remove fuses with one or both terminals energized at more than 300 volts, or with exposed parts energized at more than 50 volts, the employer shall ensure that the employee uses tools or gloves rated for the voltage. When an employee installs or removes expulsion-type fuses with one or both terminals energized at Submit Feedback

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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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# TABLE 7 INCIDENT HEAT ENERGY FOR VARIOUS FAULT CURRENTS, CLEARING TIMES, AND VOLTAGES: LIVE-LINE TOOL EXPOSURES INVOLVING PHASE-TO-GROUND ARCS IN OPEN AIR ONLY * t # # (cont.) ## B. Selecting Protective Clothing and Other Protective Equipment (cont.) <table><tr><th rowspan="2">Exposure</th><th colspan="3">Minimum head and face protection</th></tr><tr><td>None *</td><td>Arc-rated faceshield with a minimum rating of 8 cal/cm2*</td><td>Arc-rated hood or faceshield with balaclava</td></tr><tr><td>Single-phase, open air</td><td>2-8 cal/cm2</td><td>9-12 cal/cm2</td><td>13 cal/cm2 or higher f.</td></tr><tr><td>Three-phase</td><td>2-4 cal/cm2</td><td>5-8 cal/cm2</td><td>9 cal/cm2 or higher #.</td></tr><tr><td colspan="4">* These ranges assume that employees are wearing hardhats meeting the specifications in 1910.135 or $ 1926.100(b)(2), as applicable.</td></tr><tr><td colspan="4">The arc rating must be a minimum of 4 cal/cm2 less than the estimated incident energy. Note that $ 1910.269(I)(8)(v)(E) permits this type of head and face protection, with a minimum arc rating of 4 cal/cm2 less than the estimated incident energy, at any incident energy level.</td></tr><tr><td colspan="4">Note that $ 1910.269(I)(8)(v) permits this type of head and face protection at any incident energy level.</td></tr></table> ## IV. Protection Against Ignition Paragraph (I)(8)(iii) of § 1910.269 prohibits clothing that could melt onto an employee's skin or that could ignite and continue to burn when exposed to flames or to the available heat energy estimated by the employer under $ 1910.269(I)(8)(ii). Meltable fabrics, such as acetate, nylon, polyester, and polypropylene, even in blends, must be avoided. When these fibers melt, they can adhere to the skin, thereby transferring heat rapidly, exacerbating burns, and complicating treatment. These outcomes can result even if the meltable fabric is not directly next to the skin. The remainder of this section focuses on the prevention of ignition. …