Arc Flash Hazard Analysis Paper
Arc Flash Hazard Analysis and Protection
Identify
Within the past few years, the Occupational Safety and Health Administration (OSHA) implemented new employer rules concerning arc flash and the establishment of employee protection. (Foulke, 2006) The purposes of this paper it to increase knowledge about the hazards involving arch flash and how to establish the required protection zones.
Explain
Arc flash is a type of electrical explosion that results from a low-impedance connection to ground or another voltage phase in an electrical system. (Hoagland, 2009) The guidelines and regulations regarding arc flash hazards since 1971 have not focused industry 's attention on quantifying the dangers of arc flash events …show more content…
in energized low and medium voltage electrical equipment. Due to the lack of attention paid to regulations, many rules were overlooked or just not complied with. (Department of Labor, 2005) The biggest problem I have is with understanding the new rules is in establishing protection zones around a possible arc flash site. The selection of the proper personal protection equipment (PPE) for working with exposed electrical conductors centers on understanding these zones and applying then to all areas. Document
It helps to know a little history on arc flash. Ralph Lee (a prominent electrical researcher) describe it as a thermal event associated with an electric arc and its effects on the human body equal to the lower limits for the 3rd degree burn.(Ralph, 2000) The research that Ralph Lee published is still used today to calculate the level of burn distance for an arc flash. From his paper there were other papers written on how to identify personal protective equipment, what protection level they should be used at, and how to correctly use lee 's formula. (Lane, 2003)
Arc flash as been happening and hurting employees for years without having seen any new regulations. Due to the rise in the number of accidents over the past years OHSA is now working with NFPA to develop new regulations in the 2012 NFPA 70E. (NFPA Catalog, 2012) Once this has been printed and incorporated by reference into the OSHA regulations, understanding the zones should become easier for everyone to follow. Reported by John Lane in his 2003 paper on Arc-flash Hazard Analysis, the OSHA and NFPA regulations requiring arch flash protection of employees read as follows:
OSHA 29 CFR 1910.132 (d) requires employers to assess the workplace to determine if hazards are present, or likely to be present, and select and have each employee use the types of PPE that will protect them. The employer shall also communicate these decisions to the affected employees. The employer shall also verify that the required workplace hazard assessment has been performed through a written certification that identifies the particular workplace evaluated.
OSHA 29 CFR 1910.333 requires employees who are exposed to electrical shock hazard to be qualified for the specific task they are performing. This involves not only safe work practices but using the appropriate Personal Protection Equipment .
OSHA 29 CFR 1910.335 (a)(1)(i) states that employees working in areas where there are potential 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 for the work to be performed.
OSHA 29 CFR 1910.335 (a)(2)(i) states that 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. If the insulating capability of insulated tools or handling equipment is subject to damage, the insulating material shall be protected.
OSHA 29 CFR 1910.335 (a)(2)(ii) states that protective shields, protective barriers, or insulating materials shall be used to protect each employee from shock, burns, or other electrical related injuries while the employee is working near exposed energized parts which might be accidentally contacted or where dangerous electric heating or arcing might occur. When normally enclosed live parts are exposed for maintenance or repair, they shall be guarded to protect unqualified persons from contact with the live parts.
NFPA 70 E-2000, part II, Chapter 2, paragraph 2-1.3.3 states that a flash hazard analysis must be performed in order to determine the level of hazard and appropriate PPE for given tasks. ...NFPA 70E provides the formulas and tables needed to solve for the incident energy. On the surface, it may appear relatively easy to perform an arc-flash calculation. But as one gets deeper and deeper into the calculations it can become very puzzling. The three-phase bolted fault current on the low side of a transformer feeding a line of switchgear can be calculated. Use the worst case by assuming an infinite bus to give maximum fault current. An infinite bus assumes that the impedance ahead of a device is essentially zero. Then assume a fault clearing time of around 0.2 seconds and a working distance of 18 inches. Based on this data, one may think they are calculating the worst-case scenario for incident energy in calories per centimeter squared (cal/cm2).
Lane goes on to describe the approach boundaries needed to assure employees safety. These boundaries factor in the heat radiating from the blast, the actual blast associated with an arc flash and the experience level of the employee working on or near the arc flash area. Other factors such as current, voltage, and environment all play into how far and by who when it comes to dealing with the circuit. Lane 's suggested boundaries are:
Limited Approach Boundary- A shock protection boundary not to be crossed by unqualified persons unless escorted by a qualified person.
Restricted Approach Boundary- A shock protection boundary to be crossed by only qualified
persons.
When crossed the use of shock protection techniques and equipment is required.
Prohibited Approach Boundary- A shock protection boundary only to be crossed by qualified persons. When crossed the same protection is required as if direct contact is made with the live part.
Flash Protection Boundary- Distance at which the incident energy level equals 1.2 cal/cm2 for faulting clearing time greater than 0.1 seconds. Use 1.5 cal/cm2 for clearing times that are 0.1 seconds or faster.
In conclusion, the research I found helped me understand that the distance and type of PPE is proportionate to the current and type of circuit employees are dealing with. The information above has shown what risk you take every time you work with electricity. The best way to prevent an accident when working on electrical equipment is to de-energize the equipment first and use PPE and the protective zones when disconnecting or adjusting the circuit. There is no substitution for having the training that is need and for being able to de-energize and work on equipment. You will probably not get a second chance if you are involved in an electrical
accident.
References
Foulke, E. G. Department of Labor, Occupational Safety and Health Administration. (2006). Letter of Interpretation, MS. Joanne Linard (11/14/2006).
Department of Labor. Department of Labor, Occupational Safety and Health Administration. (2005). Electric power generation, transmission, and distribution; electrical protective equipment (05-11585). Retrieved from National Archives and Records Administration website: https://www.federalregister.gov/articles/2005/06/15/05-11585/electric-power-generation-transmission-and-distribution-electrical-protective-equipment
Hoagland, H. (2009).Arc flash training & ppe protection.
In Arc Flash Training & PPE Protection. Occupational Health and Safety. Retrieved from http://ohsonline.com/articles/2009/08/03/arc-flash-training-ppe.aspx
Lane, J. (2003, June 02). Arc-flash hazard analysis "putting the pieces together". Retrieved from http://www.avotraining.com/common/documents/John Lane ARC-FLASH PAPER.pdf
NFPA Catalog. (2012). Nfpa 70e®: Standard for electrical safety in the workplace®, 2012 edition. Retrieved from http://www.nfpa.org/catalog/product.asp?pid=70E12&icid=B484&link_type=doc_info_buybox
Ralph Lee, (2000, March/April)The Other Electrical Hazard, Electric Arc Blast Burns. IEEE Trans Ind. Applicat., vol 36, No. 2, pp 659-667
Identify
Within the past few years, the Occupational Safety and Health Administration (OSHA) implemented new employer rules concerning arc flash and the establishment of employee protection. (Foulke, 2006) The purposes of this paper it to increase knowledge about the hazards involving arch flash and how to establish the required protection zones.
Explain
Arc flash is a type of electrical explosion that results from a low-impedance connection to ground or another voltage phase in an electrical system. (Hoagland, 2009) The guidelines and regulations regarding arc flash hazards since 1971 have not focused industry 's attention on quantifying the dangers of arc flash events …show more content…
in energized low and medium voltage electrical equipment. Due to the lack of attention paid to regulations, many rules were overlooked or just not complied with. (Department of Labor, 2005) The biggest problem I have is with understanding the new rules is in establishing protection zones around a possible arc flash site. The selection of the proper personal protection equipment (PPE) for working with exposed electrical conductors centers on understanding these zones and applying then to all areas. Document
It helps to know a little history on arc flash. Ralph Lee (a prominent electrical researcher) describe it as a thermal event associated with an electric arc and its effects on the human body equal to the lower limits for the 3rd degree burn.(Ralph, 2000) The research that Ralph Lee published is still used today to calculate the level of burn distance for an arc flash. From his paper there were other papers written on how to identify personal protective equipment, what protection level they should be used at, and how to correctly use lee 's formula. (Lane, 2003)
Arc flash as been happening and hurting employees for years without having seen any new regulations. Due to the rise in the number of accidents over the past years OHSA is now working with NFPA to develop new regulations in the 2012 NFPA 70E. (NFPA Catalog, 2012) Once this has been printed and incorporated by reference into the OSHA regulations, understanding the zones should become easier for everyone to follow. Reported by John Lane in his 2003 paper on Arc-flash Hazard Analysis, the OSHA and NFPA regulations requiring arch flash protection of employees read as follows:
OSHA 29 CFR 1910.132 (d) requires employers to assess the workplace to determine if hazards are present, or likely to be present, and select and have each employee use the types of PPE that will protect them. The employer shall also communicate these decisions to the affected employees. The employer shall also verify that the required workplace hazard assessment has been performed through a written certification that identifies the particular workplace evaluated.
OSHA 29 CFR 1910.333 requires employees who are exposed to electrical shock hazard to be qualified for the specific task they are performing. This involves not only safe work practices but using the appropriate Personal Protection Equipment .
OSHA 29 CFR 1910.335 (a)(1)(i) states that employees working in areas where there are potential 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 for the work to be performed.
OSHA 29 CFR 1910.335 (a)(2)(i) states that 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. If the insulating capability of insulated tools or handling equipment is subject to damage, the insulating material shall be protected.
OSHA 29 CFR 1910.335 (a)(2)(ii) states that protective shields, protective barriers, or insulating materials shall be used to protect each employee from shock, burns, or other electrical related injuries while the employee is working near exposed energized parts which might be accidentally contacted or where dangerous electric heating or arcing might occur. When normally enclosed live parts are exposed for maintenance or repair, they shall be guarded to protect unqualified persons from contact with the live parts.
NFPA 70 E-2000, part II, Chapter 2, paragraph 2-1.3.3 states that a flash hazard analysis must be performed in order to determine the level of hazard and appropriate PPE for given tasks. ...NFPA 70E provides the formulas and tables needed to solve for the incident energy. On the surface, it may appear relatively easy to perform an arc-flash calculation. But as one gets deeper and deeper into the calculations it can become very puzzling. The three-phase bolted fault current on the low side of a transformer feeding a line of switchgear can be calculated. Use the worst case by assuming an infinite bus to give maximum fault current. An infinite bus assumes that the impedance ahead of a device is essentially zero. Then assume a fault clearing time of around 0.2 seconds and a working distance of 18 inches. Based on this data, one may think they are calculating the worst-case scenario for incident energy in calories per centimeter squared (cal/cm2).
Lane goes on to describe the approach boundaries needed to assure employees safety. These boundaries factor in the heat radiating from the blast, the actual blast associated with an arc flash and the experience level of the employee working on or near the arc flash area. Other factors such as current, voltage, and environment all play into how far and by who when it comes to dealing with the circuit. Lane 's suggested boundaries are:
Limited Approach Boundary- A shock protection boundary not to be crossed by unqualified persons unless escorted by a qualified person.
Restricted Approach Boundary- A shock protection boundary to be crossed by only qualified
persons.
When crossed the use of shock protection techniques and equipment is required.
Prohibited Approach Boundary- A shock protection boundary only to be crossed by qualified persons. When crossed the same protection is required as if direct contact is made with the live part.
Flash Protection Boundary- Distance at which the incident energy level equals 1.2 cal/cm2 for faulting clearing time greater than 0.1 seconds. Use 1.5 cal/cm2 for clearing times that are 0.1 seconds or faster.
In conclusion, the research I found helped me understand that the distance and type of PPE is proportionate to the current and type of circuit employees are dealing with. The information above has shown what risk you take every time you work with electricity. The best way to prevent an accident when working on electrical equipment is to de-energize the equipment first and use PPE and the protective zones when disconnecting or adjusting the circuit. There is no substitution for having the training that is need and for being able to de-energize and work on equipment. You will probably not get a second chance if you are involved in an electrical
accident.
References
Foulke, E. G. Department of Labor, Occupational Safety and Health Administration. (2006). Letter of Interpretation, MS. Joanne Linard (11/14/2006).
Department of Labor. Department of Labor, Occupational Safety and Health Administration. (2005). Electric power generation, transmission, and distribution; electrical protective equipment (05-11585). Retrieved from National Archives and Records Administration website: https://www.federalregister.gov/articles/2005/06/15/05-11585/electric-power-generation-transmission-and-distribution-electrical-protective-equipment
Hoagland, H. (2009).Arc flash training & ppe protection.
In Arc Flash Training & PPE Protection. Occupational Health and Safety. Retrieved from http://ohsonline.com/articles/2009/08/03/arc-flash-training-ppe.aspx
Lane, J. (2003, June 02). Arc-flash hazard analysis "putting the pieces together". Retrieved from http://www.avotraining.com/common/documents/John Lane ARC-FLASH PAPER.pdf
NFPA Catalog. (2012). Nfpa 70e®: Standard for electrical safety in the workplace®, 2012 edition. Retrieved from http://www.nfpa.org/catalog/product.asp?pid=70E12&icid=B484&link_type=doc_info_buybox
Ralph Lee, (2000, March/April)The Other Electrical Hazard, Electric Arc Blast Burns. IEEE Trans Ind. Applicat., vol 36, No. 2, pp 659-667