Safe Work Practices and Procedures for 480V Electrical Panels

This document outlines the safe work practices and procedures for working in proximity to or performing maintenance on 480V electrical panels. It includes guidelines for lockout/tagout (LOTO), arc flash prevention, and the appropriate use of personal protective equipment (PPE). These procedures are designed to minimize the risk of electrical shock, arc flash, and other electrical hazards.

General Safety Practices

• Employ safety-related work practices to prevent electric shock or other injuries from direct or indirect electrical contacts when working near or on energized equipment or circuits. The practices should be consistent with the nature and extent of the electrical hazards. [Citation: 18, 1910.333 (a)]
• De-energize live parts before working on or near them, unless de-energizing introduces additional hazards or is infeasible due to equipment design or operational limitations. Live parts operating at less than 50 volts to ground need not be de-energized if there is no increased exposure to electrical burns or explosions due to electric arcs. [Citation: 11, WAC 296-24-975]
• If de-energizing is not possible, use other safety-related work practices to protect against contact with energized circuit parts, either directly or indirectly through conductive objects. These practices must be suitable for the conditions and voltage level. [Citation: 11, WAC 296-24-975]
• When working near exposed energized conductors or circuit parts, use insulated tools or handling equipment. Protect the insulating material if its capability is subject to damage. [Citation: 14, 1910.335(a)(2)(i)]
• Use protective shields, barriers, or insulating materials to protect employees from shock, burns, or other electrical injuries when working near exposed energized parts. Guard normally enclosed live parts that are exposed for maintenance or repair to protect unqualified persons from contact. [Citation: 14, 1910.335(a)(2)(ii)]
• Use safety signs, symbols, or accident prevention tags to warn employees about electrical hazards. [Citation: 14, 1910.335(b)(1)]
• Use barricades with safety signs to prevent or limit access to areas with uninsulated energized conductors or circuit parts. Do not use conductive barricades where they might cause an electrical contact hazard. [Citation: 14, 1910.335(b)(2)]
• If signs and barricades are insufficient, station an attendant to warn and protect employees from electrical hazards. [Citation: 14, 1910.335(b)(3)]
• Ensure illumination is provided to allow employees to perform work safely in spaces containing exposed energized parts. [Citation: 19, 1910.333 (c)(4)(i)]
• When working in confined or enclosed spaces with exposed energized parts, use protective shields, barriers, or insulating materials to prevent inadvertent contact. Secure doors and hinged panels to prevent them from swinging into an employee and causing contact with energized parts. [Citation: 19, 1910.333 (c)(5)]
• Handle conductive materials and equipment in a manner that prevents them from contacting exposed energized conductors or circuit parts. Use work practices such as insulation, guarding, and material handling techniques to minimize hazards when handling long dimensional conductive objects. [Citation: 19, 1910.333 (c)(6)]
• Portable ladders shall have nonconductive siderails if they are used where the employee or the ladder could contact exposed energized parts. [Citation: 16, 1910.333 (c)(7)]
• Do not wear conductive articles of jewelry and clothing (such as watch bands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread, or metal headgear) if they might contact exposed energized parts. Such articles may be worn if they are rendered nonconductive by covering, wrapping, or other insulating means. [Citation: 16, 1910.333 (c)(7)]
• Where live parts present an electrical contact hazard, employees may not perform housekeeping duties at such close distances to the parts that there is a possibility of contact, unless adequate safeguards (such as insulating equipment or barriers) are provided. Electrically conductive cleaning materials (including conductive solids such as steel wool, metalized cloth, and silicon carbide, as well as conductive liquid solutions) may not be used in proximity to energized parts unless procedures are followed which will prevent electrical contact. [Citation: 16, 1910.333 (c)(7)]
• Only a qualified person following the requirements of paragraph (c) of this section may defeat an electrical safety interlock, and then only temporarily while he or she is working on the equipment. The interlock system shall be returned to its operable condition when this work is completed. [Citation: 16, 1910.333 (c)(7)]

Lockout/Tagout (LOTO) Procedures

• Follow lockout/tagout procedures as part of a hazardous energy control program whenever possible. [Citation: 1, Arc Flash]
• Maintain a written copy of lockout/tagout procedures and make it available for inspection by employees and authorized representatives. [Citation: 3, WAC 296-24-975]
• Determine safe procedures for de-energizing circuits and equipment before de-energization. [Citation: 3, WAC 296-24-975]
• Disconnect circuits and equipment from all electric energy sources. Do not use control circuit devices (e.g., push buttons, selector switches, interlocks) as the sole means for de-energizing. Do not use interlocks as a substitute for lockout and tagging procedures. [Citation: 3, WAC 296-24-975]
• Release stored electric energy that might endanger personnel. Discharge capacitors and short-circuit and ground high capacitance elements if stored energy might be hazardous. Treat capacitors and associated equipment as energized when handling them for this purpose. [Citation: 3, WAC 296-24-975]
• Block stored non-electrical energy in devices that could re-energize electric circuit parts or relieve it to prevent accidental energization. [Citation: 3, WAC 296-24-975]
• Place a lock and a tag on each disconnecting means used to de-energize circuits and equipment, except where specified alternatives are permitted. Attach the lock to prevent operation of the disconnecting means without undue force or tools. [Citation: 3, WAC 296-24-975]
• Each tag must contain a statement prohibiting unauthorized operation of the disconnecting means and removal of the tag. [Citation: 7, 1910.333 (b)(2)(iii)(B)]
• If a lock cannot be applied, or if the employer can demonstrate that tagging procedures will provide a level of safety equivalent to that obtained by the use of a lock, a tag may be used without a lock. [Citation: 20, 1910.333(b)(2)(iii)(C)]
• A tag used without a lock shall be supplemented by at least one additional safety measure that provides a level of safety equivalent to that obtained by use of a lock. Examples of additional safety measures include the removal of an isolating circuit element, blocking of a controlling switch, or opening of an extra disconnecting device. [Citation: 20, 1910.333(b)(2)(iii)(D)]
• A lock may be placed without a tag only under the following conditions: Only one circuit or piece of equipment is deenergized, and The lockout period does not extend beyond the work shift, and Employees exposed to the hazards associated with reenergizing the circuit or equipment are familiar with this procedure. [Citation: 20, 1910.333(b)(2)(iii)(E)]
• Before any circuits or equipment can be considered and worked as deenergized, A qualified person shall operate the equipment operating controls or otherwise verify that the equipment cannot be restarted. [Citation: 20, 1910.333(b)(2)(iv)(A)]
• A qualified person shall use test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall verify that the circuit elements and equipment parts are deenergized. The test shall also determine if any energized condition exists as a result of inadvertently induced voltage or unrelated voltage back-feed even though specific parts of the circuit have been deenergized and presumed to be safe. If the circuit to be tested is over 600 volts, nominal, the test equipment shall be checked for proper operation immediately after this test. [Citation: 20, 1910.333(b)(2)(iv)(B)]
• Before circuits or equipment are reenergized, even temporarily, A qualified person shall conduct tests and visual inspections, as necessary, to verify that all tools, electrical jumpers, shorts, grounds, and other such devices have been removed, so that the circuits and equipment can be safely energized. [Citation: 20, 1910.333(b)(2)(v)(A)]
• Employees exposed to the hazards associated with reenergizing the circuit or equipment shall be warned to stay clear of circuits and equipment. [Citation: 20, 1910.333(b)(2)(v)(B)]
• Each lock and tag shall be removed by the employee who applied it or under his or her direct supervision. However, if this employee is absent from the workplace, then the lock or tag may be removed by a qualified person designated to perform this task provided that: The employer ensures that the employee who applied the lock or tag is not available at the workplace, and The employer ensures that the employee is aware that the lock or tag has been removed before he or she resumes work at that workplace. [Citation: 20, 1910.333(b)(2)(v)(C)]
• There shall be a visual determination that all employees are clear of the circuits and equipment. [Citation: 20, 1910.333(b)(2)(v)(D)]

Arc Flash Prevention

• Whenever possible, do not work on energized equipment. [Citation: 1, Arc Flash]
• Ensure conductors and circuit parts are in a safe working condition. [Citation: 1, Arc Flash]
• Use lower energy equipment or current energy limiting devices. [Citation: 1, Arc Flash]
• Guard energized electrical conductors and circuit parts. [Citation: 1, Arc Flash]
• Use arc flash approach boundaries, including barricades. [Citation: 1, Arc Flash]
• Increase the working distance. [Citation: 1, Arc Flash]
• Use non-contact instruments or procedures where possible. [Citation: 1, Arc Flash]
• Use non-sparking tools. [Citation: 1, Arc Flash]
• Implement work permits, safe work procedures, and job planning. [Citation: 1, Arc Flash]
• Post signs alerting of the hazards. [Citation: 1, Arc Flash]
• 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. [Citation: 1, Arc Flash]
• Regular measurements of critical components. [Citation: 1, Arc Flash]
• 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). [Citation: 1, Arc Flash]
• Follow established maintenance requirements, including a parts replacement schedule. [Citation: 1, Arc Flash]
• Keep electrical drawings current. [Citation: 1, Arc Flash]
• 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). [Citation: 13, Arc Flash]
• 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. [Citation: 13, Arc Flash]

Personal Protective Equipment (PPE)

• Provide employees working in areas with potential electrical hazards with appropriate electrical protective equipment for the specific body parts to be protected and the work to be performed, and ensure they use it. [Citation: 2, WAC 296-24-980]
• Maintain protective equipment in a safe, reliable condition and inspect or test it periodically. [Citation: 2, WAC 296-24-980]
• Protect the insulating material of protective equipment if it may be subject to damage during use. [Citation: 2, WAC 296-24-980]
• Wear nonconductive head protection where there is a danger of head injury from electric shock or burns due to contact with exposed energized parts. [Citation: 2, WAC 296-24-980]
• Wear protective equipment for the eyes or face where there is danger of injury from electric arcs or flashes or from flying objects resulting from electrical explosion. [Citation: 2, WAC 296-24-980]
• Workers must know how to select, use, and care for the necessary PPE, and understand the limitations of the PPE. [Citation: 5, Arc Flash]
• 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: The incident energy analysis, The arc flash PPE category. [Citation: 5, Arc Flash]
• 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). [Citation: 5, Arc Flash]
• In addition to the appropriate clothing and footwear, other PPE items, such as a hard hat (class G or E), face shield, balaclava, hood, safety glasses or goggles, heavy duty leather/arc- rated/rubber insulating gloves, hearing protection, and footwear are required when there is a risk of arc flash incident. All PPE used must be appropriate for energy expected if an arc flash occurs. [Citation: 5, Arc Flash]

Qualified Persons

• Only qualified persons may work on electric circuit parts or equipment that have not been deenergized. [Citation: 4, 1910.333(c)(2)]
• 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. [Citation: 5, Arc Flash]
• 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. [Citation: 5, Arc Flash]

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