Estimated that 2,000 workers are treated in specialized burn centers each year as a result of arc flash (Electrical Safety Foundation International). According to the National Safety Council, medical costs for severe electrical burns can exceed $4 million per person.
80% of electrical injuries and fatalities among Qualified Workers are caused by arc flash/arc blast (Bureau of Labor Statistics). According to the NFPA, an estimated 5-10 arc flash explosions occur daily in the U.S.
Sudden release of electrical energy through air following a phase to phase or phase to ground fault. All Rights Reserved
Release of concentrated energy in the form of heat and light: Fraction of a second Faster than the human eye All Rights Reserved
Working near exposed electrical parts that have not been placed in a safe working condition (ZERO Energy State). Employees must be protected during energy isolation and verification. At times these activities may expose persons to exposed electrical parts.
Troubleshooting Live Circuits Opening Or Closing Circuits Grounding Circuits
Un-insulated Tool Contact Loose Parts, Components Knockout, loose connection, etc. Accidental Contact W/live Parts Water Rodents All Rights Reserved
Can be equal To 4 Times The Surface Of The Sun (Approximately 35,000 F ] Change solids to hot molten metal and to vapor. Superheats surrounding air which expands in an explosive manner (Arc Blast). Results in high pressure waves and a conductive plasma cloud. Pressure waves hurl shrapnel and hot molten material at speeds of up to 700 mph.
Arc burns by radiant heat. Thermal contact burns. Electrical burns from current flow. Death!
Metal Expansion During Blast Copper Expands 67000 Times (1 In³ = 1.44 Yds³ Vapor) Expansion Produces Molten Metal Fragmented Metal High Temperatures Pressure On The Body Sound Waves (140-165 db)
Creates wave of pressure hundreds or thousands of pounds per square foot. Hurl switchgear Push over concrete walls Send molten material flying at high velocities Damage to equipment/nearby structures
Physical Injuries From Arc Blasts Can Include: Severe burns Blindness Impact w/objects (shrapnel) Ruptured eardrums DEATH!!!! All Rights Reserved
NFPA/OSHA
Several industry standards establish practices for protection against arc flash. OSHA 29 CFR Part 1910, Subpart S establishes standards for work practices. NFPA 70E Standard for Electrical Safety Requirements for Employee Workplaces. NFPA 70E requirements for arc flash warning labels.
OSHA 1910.132 - PPE Employer is responsible to assess the hazards in the workplace and to select, have, and use correct PPE, and to document the assessment. 1910.335 (a)(1)(i) Employees working in areas where there are potential for electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body to be protected and the work to be performed.
1910.335(a)(2)(i) - Employees shall wear protective equipment for the eyes and face whenever there is danger of injury to the eyes and face from electric arcs or flashes or from flying objects resulting from electrical explosion.
OSHA does require employers to protect their employees from arc flash. However, OSHA regulations themselves do not provide enough detailed information to accomplish this. OSHA references NFPA 70E in a standard interpretation Letter dated 11/14/2006.
OSHA recommends that employers consult consensus standards such as NFPA 70E 2004 to identify safety measures that can be used to comply with or supplement the requirements of OSHA s standard for preventing or protecting against arc flash hazards.
Primary means of protecting persons from arc flash hazards is to de-energize live parts prior to working on or near them and to use lockout tagout. Remember employees may still be exposed to live parts during shut-down and verification.
NFPA uses hazard categories (0-4) based on the incident energy of the circuit. These hazard categories communicate the level of personal protective equipment required. Each category provides progressively more thermal protection.
Task based tables in 70E that list type of equipment and the task being performed. Downside is not enough detailed information such as where equipment is located.
Have a complete Arc Flash Analysis/Study. Data is collected and software is used to perform calculations to determine the flash hazard levels. Also helpful as it includes instructions on how these levels may be reduced (fuse replacement, breaker adjustment, current limiting devices, etc.)
Added benefit is that it will identify situations where employees will not have to wear as much equipment as referenced in the tables. Tables often calculate higher hazard risk categories.
If your facility is not currently using a method for determining the level of protection, at a minimum consult the tables in NFPA 70E.
Determines the worker s potential exposure to arc flash energy. Determines: Flash Protection Boundary, Restricted Approach Boundary, Prohibited Approach Boundary, Limited Approach Boundary. Incident Energy Appropriate Levels of PPE/Safe Work Practices Proper Labeling Conducted by: Certified Electrical Engineers/Electricians.
Data is Collected and Entered into Arc Flash Software Program. Data Collected: Utility Service Information As Built Single Line Diagrams Transformer type, size and impedance Cable Sizes and Lengths Protective Device Type, Size, and Settings
Field markings are determined to warn qualified persons of the potential for arc flash hazards on equipment likely to require maintenance while energized.
CATEGORY 0 MINIMUM ARC RATING 0-1.2 cal/cm 2 PERSONAL PROTECTIVE EQUIPMENT HEAD BODY HAND/ARM FOOT Safety glasses, hearing protection Non-melting or untreated natural fibers, long sleeve shirt and long pants > Voltage-rated tools plus class 0 gloves and leather protectors Dielectric soles or rubber mat 1 1.2-4 cal/cm 2 Safety glasses, hearing protection, electricallyrated hard hat, face shield 4 cal/sq cm rated, fire retardant (FR) long sleeve shirt and FR long pants or FR coveralls Voltage-rated tools plus class 0 gloves and leather protectors Leather shoes, dielectric soles, or insulating mat 2 4-8 cal/cm 2 protection, electricallyrated hard hat, face Safety glasses, hearing shield 8 cal/sq cm rated, cotton underwear, fire retardant (FR) long sleeve shirt and FR long pants or FR coveralls/coat Voltage-rated tools plus class 0 gloves and leather protectors Leather shoes, dielectric soles, or insulating mat 3 8-25 cal/cm 2 Safety glasses, hearing protection, electricallyrated hard hat, face shield 25 cal/sq cm rated, cotton underwear, fire retardant (FR) long sleeve shirt and FR long pants or FR coveralls/coat Voltage-rated tools plus class 0 gloves and leather protectors Leather shoes, dielectric soles, or insulating mat 4 25-40 cal/cm 2 Safety glasses, hearing protection, electricallyrated hard hat, face shield 40 cal/sq cm rated, cotton underwear, fire retardant (FR) long sleeve shirt and FR long pants plus layered flash suit Voltage-rated tools plus class 0 gloves and leather protectors Leather shoes, dielectric soles, or insulating mat
Switchboards Panelboards Industrial Control Panels Motor Control Centers All Rights Reserved
NFPA 70E
Protect the following areas: Head, neck and face. Eye Protection Body Protection Hand and Arm Kits available in several ratings (8 cal, 12 cal, etc.) All Rights Reserved
NFPA 70E 2-3.7 Insulated Tools and Equipment Employees shall use insulated tools and/or handling equipment when working inside the limited approach boundary of live parts where tools or handling equipment might make accidental contact.
OSHA 1910.335(a)(2)(i) When working near exposed energized conductors or circuit parts, each employee shall use insulated tools or handling equipment if the tools or handling equipment might make contact with such conductors or parts.
Usually Orange/ Red In Color Symbol Of Overlapped Triangle (Double Delta) Labeled Ac1000v Some Tools May Look Insulated But Are In Fact Not!
OSHA Fuse handling equipment, insulated for the circuit voltage shall be used to remove or install fuses when fuse terminals are energized.
Host Employer Responsibilities: Inform contract employers of any known hazards covered within OSHA/NFPA 70E standards that might not be recognized by the contract employer or its employees. Inform contract employers of the type of installations and the need to assess equipment prior to the start of work.
Safety is more than compliance, it is making the best effort to protect employees. NFPA 70 E offers much more detailed guidance on properly protecting employees.
This presentation was developed to give general safety information on the hazards of electrical arc flash. Progressive Safety Services LLC (Progressive Safety) does not make any representation or warranty as to the accuracy or completeness of the information in this presentation. Refrain from doing any act or omission that are reasonably foreseeable that a particular other person (or class of persons) is likely to suffer damage or loss as a result of the act or omission. Progressive Safety is excluded from liability for negligence for both personal injury and damage to property. The information within this presentation is general. It does not constitute and should not be relied on as legal advice. Progressive Safety Services LLC tries to ensure that the content of this presentation is accurate, adequate or complete, it does not represent or warrant or its accuracy, adequacy of completeness.
Joe Mlynek CSP, OHST Joe.mlynek@progressivesafety.us