Arc Flash Safety - Institute for Safety in Powerline Construction
SAFETY MEETING TOPICS ARC FLASH SAFETY Copyright by the Institute for Safety in Powerline Construction 3504 Parliament Ct. Alexandria, LA 71303 All rights reserved. This material or any part thereof may not be reproduced in any form without the written permission of the
Institute for Safety in Powerline Construction WHAT IS AN ARC FLASH An arc flash is a short circuit through the air. When the insulation or isolation between electrified conductors is breached or can no longer withstand the applied voltage, an arc flash occurs. WHAT IS AN ARC FLASH
Electricity will go through the path of least resistance. When the path of electricity is suddenly interrupted, the electricity will create a new pathway. COST OF TREATMENT 97% of electricians have been shocked or injured on the job. Every 30 minutes during the work day, a worker suffers an electrically induced injury
that requires time off the job for recovery. Over the last ten years, more than 46,000 workers have been injured from on-the-job electrical hazards. Medical costs for severe electrical burns can exceed $4M per person. Work-related injuries can cost businesses well over $30M in fines, medical costs, litigation, lost business and equipment costs. CAUSES OF AN ELECTRICAL ARC Some arcs are caused by human error,
including: Dropped tools, Accidental contact with electrical systems, Improper work procedures. Mechanical breakdown/failure Current overload
CAUSES OF AN ELECTRICAL ARC Some other common causes of an arc flash are: Insulation failure. Buildup of dust, impurities, and corrosion Sparks produced during racking of breakers, replacement of fuses, and closing into faulted
lines Birds, bees, and rodents PREVENTING ARC FLASH INCIDENTS The best way to prevent arc flash incidents from occurring is to deenergize equipment before beginning work and creating an electrically safe work condition. ELECTRICALLY SAFE WORK CONDITION Both OSHA standards and NFPA require:
Employees or electrical contractors are required to place equipment in an electrically safe condition before work begins on or near them. De-energize the equipment and verify that fact before beginning work. WORKING ON ENERGIZED OR LIVE EQUIPMENT It is always preferable to work on de-energized equipment. De-energizing introduces additional or increased hazards such as
cutting ventilation to a hazardous location OR Infeasible because of equipment design or operational limitations such as when voltage testing is required for diagnostic purposes. PLACING EQUIPMENT IN AN ELECTRICALLY SAFE WORK CONDITION With careful planning, work can almost always be done with equipment de-energized.
Placing equipment in an electrically safe work condition involves a number of steps that have to be taken before the equipment is in a safe condition. Appropriate protective precautions, including the use of PPE, are necessary during the deenergizing process. PLACING EQUIPMENT IN AN ELECTRICALLY SAFE WORK CONDITION Workers must take the following steps to ensure that an electrically safe work condition exists:
Find all possible sources of supply. Open disconnecting device(s) for each source. Where possible, visually verify device is open. Apply lock-out/tag-out devices. Test voltage on each conductor to verify that it's de-energized. Apply grounding devices where stored energy or
induced voltage could exist or where de-energized conductors could contact live parts. SAFETY PROTECTION PROCEDURES In the few instances where turning off the power could create a greater hazard to people or processes than leaving it on. New industry standards are designed to protect workers and the workplace. These standards place responsibility on employers and facility owners
SAFETY PROTECTION PROCEDURES NFPA 70E, NEC, OSHA 1910 Subpart S, and ASTM requirements: A safety program with defined responsibilities Calculations for the degree of arc flash hazard PPE for workers Training for workers Tools for safe work Warning labels on equipment STANDARD FOR ELECTRICAL SAFETY IN
THE WORKPLACE National Electric Code (NEC)American National Electric Standard. Practices and procedures are intended to provide for employee safety relative to electrical hazards (including flashes and contacts) in the workplace.
Employers must formalize procedures and practices Employers must provide training for employees Arc Flash and Shock Hazard Employees must implement the Appropriate PPE Required practices according to the Courtesy E.I. du Pont de Nemours & Co. training. Companies must perform a flash hazard analysis
! WARNING NFPA 70-E - Standard for Electrical Safety in the Workplace 130.5 Arc Flash Hazard Analysis An arc flash hazard analysis (electrical assessment) shall determine the arc flash boundary, the incident energy at the working distance, and the personal protective equipment that people within the arc flash boundary shall use. The arc flash hazard analysis shall be updated when a major modification or renovation takes place. It shall be reviewed periodically, not to exceed 5
years, to account for changes in the electrical distribution system that could affect the results of the arc flash hazard analysis. The arc flash hazard analysis shall take into consideration the design of the overcurrent protective device and its opening time, including its condition of maintenance. SAFETY PROGRAM FOR ELECTRICAL ARCS Electrical Safety Program Procedure An electrical safety program shall identify the procedures for employees exposed to an electrical hazard before work is started. Employers must formalize procedures and practices
New version deleted reference to limited approach boundary and arc flash boundary SAFETY PROGRAM FOR ELECTRICAL ARCS Training Current Requirements (no change from 2012) Training must be performed every 3 years at a minimum Many companies/corporations adapt a higher degree of training for their internal requirements NFPA 70E 2015 Updates Documentation must be kept. This includes name, date and content
Employee must demonstrate skill/know-how QUALIFIED PERSON One who has received documented training in the hazards of working on energized equipment in general Has been trained in the hazards of the particular equipment to be serviced. Training must include the use and proper application of PPE. Only a qualified person is permitted to work on or near live electrical
equipment. ARC FLASH RISK ASSESSMENT ARC FLASH HAZARD ANALYSIS (OLD) Does the arc flash hazard exist? If it does: The appropriate work related practices must be implemented The arc flash boundary must be defined Arc Flash PPE must be worn when entering the arc flash boundary ARC FLASH RISK ASSESSMENT
NFPA 70-E - Standard for Electrical Safety in the Workplace Risk Assessment Procedure An electrical safety program shall include a risk assessment procedure that addresses employee exposure to electrical hazards. New Hazard identification has been deleted. New Field work shall be audited to verify electrical safety program is being followed. Audits cannot exceed 1 year. FLASH PROTECTION BOUNDARY Prohibited Approach Boundary (Eliminated in NFPA 70E 2015) Equivalent to direct contact. Any body part which crosses this boundary must be
protected with PPE rated appropriately for direct contact with the part. Why remove? it is more of a heads up boundary, too similar to the RAB Restricted Approach Boundary May only be crossed by qualified workers with appropriate PPE. In addition, a work permit is needed. Limited Approach Boundary Unqualified workers must be in PPE and accompanied by qualified worker to cross INCIDENT ENERGY LEVEL The incident energy level is the
amount of energy impressed on a surface, a certain distance from the source, generated during an electrical arc event After determining the incident energy, the value can be used to select the appropriate personal protective equipment INCIDENT ENERGY CALCULATION Incident Energy Analysis Required Incident energy analysis must be performed to determine AFB and
PPE Must be reviewed a minimum of every five years Updates required if major modifications or renovations Must consider effects of overcurrent protective devices and opening times INCIDENT ENERGY CALCULATION INCIDENT ENERGY CALCULATION IEEE Standard 1584 establishes nine steps in the analysis process: 1.
2. 3. 4. 5. 6. 7. 8. 9. Collect system and installation data. Determine modes of operation. Determine bolted fault current.
Determine arc fault current. Find protective device characteristic and arc duration. Document system voltages and equipment class. Select working distances. Calculate incident energy. Calculate the flash protection boundary. INCIDENT ENERGY CALCULATION ARC FLASH PPE CATEGORY HAZARD RISK CATEGORY (OLD)
Arc Flash PPE Category 0 Eliminated (used to be HRC 0) ARC FLASH WARNING LABELS PREVENTIVE MAINTENANCE Preventive maintenance, worker training, and an effective safety program can significantly reduce arc flash exposure. The plan should also include: Using corrosion resistant terminals and insulating exposed metal
parts if possible Sealing all open areas of equipment to ensure rodents and birds cannot enter Verifying that all relays and breakers operate properly ENGINEERING CONTROLS The incident energy exposure caused by an arc flash can be affected by the system configuration, system fault levels, and exposure time.
System fault levels can be reduced by changing the system configuration to reduce available fault current and by using current limiting devices such as fuses, breakers, and reactors. Using faster acting relays and trip devices can reduce arcing time or exposure time. Instantaneous relays could also improve clearing times, limiting the arc exposure time. Fuse sizes should also be evaluated to determine if a smaller fuse could be used, since smaller fuses reduce the exposure time.
WRAP UP It isn't possible to overstate the importance of establishing an electrical safety program. Arc flash is a serious hazard that can be devastating to those exposed to it. It can also cause lengthy downtime to repair or replace severely damaged equipment. The requirements of NFPA 70E can help plant and facility managers and other users of electricity to understand how to reduce the probability of an arc flash event and its effects. The seriousness of these hazards is demonstrated by stepped-up efforts by OSHA to ensure compliance with new industry standards, which can help reduce workplace injuries, prevent damage to equipment, and
increase uptime for any company. QUESTIONS? Any questions about what we covered? Causes of and Electrical Arc Preventing Arc Flash Incidents Electrically Safe Work Conditions Working on Energized equipment Safety Program Qualified Person
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