| What is an Arc Flash? | | | | provide specific detail of what specific personal |
| An arc flash occurs when short circuit current | | | | protective equipment is necessary to achieve the |
| flows across a gap creating an arc and can be | | | | objective. It might be considered that based on |
| anything from minor embarrassing sparks to a | | | | this generalized statement, the selection of the |
| deadly explosion. | | | | correct PPE is open to interpretation however, |
| The Arc Flash is usually caused by accidental | | | | this would be incorrect and an Arc Flash study |
| contact between energized conductors from | | | | should be performed. NFPA 70E defines many of |
| events such as dropping a screw driver or | | | | the methods." |
| touching a wire. It can produce temperatures in | | | | NFPA 70E and Arc Flash |
| the thousands of degrees, create extreme blast | | | | NFPA 70E Section 130.3(B) requires that an Arc |
| pressure, launch projectiles at hundreds of miles | | | | Flash Hazard analysisshall determine, and the |
| per hour, produce ultra-violet light that can blind. It | | | | employer shall document, the incident energy |
| can and does kill people! | | | | exposure of the worker (in calories per square |
| The IEEE 1584 Working Group has been studying | | | | centimeter). The incident energy exposure level |
| the effects of Arc Flash through testing and | | | | shall be based on the working distance of the |
| analysis which lead to the development of: IEEE | | | | employee's face and chest areas from a |
| Std.1584tm, IEEE Guide for Performing Arc Flash | | | | prospective arc source for the specific task to be |
| Hazard Calculations which defines formulas and | | | | performed. It further states that |
| procedures used to calculate the amount of | | | | …flame-resistant (FR) clothing and personal |
| incident energy that can be released during and | | | | protective equipment (PPE) shall be used by the |
| arcing short circuit. | | | | employee based on the incident energy exposure |
| What Does OSHA Say About Arc Flash? | | | | associated with the specific task.” |
| According to OSHA 1910.132(d) the employer is | | | | NFPA 70E compliance also requires determining |
| responsible to assess the hazards in the work | | | | the arc flash protection boundary, which is the |
| place, select, have, and use the correct Personal | | | | distance from a potential arc source where the |
| Protective Equipment (PPE) and document the | | | | incident energy falls to a value of 1.2 cal/cm2. This |
| assessment. The use of NFPA 70E and other | | | | value is considered to be the point at which the |
| related industry consensus standards has been | | | | onset of a second-degree burn occurs. Live work |
| used to demonstrate whether an employer acted | | | | performed outside of the flash protection |
| reasonably when there is a possible OSHA | | | | boundary does not require PPE, although the risk |
| enforcement action taken. | | | | of some injury still exists. |
| So although NFPA 70E is not directly part of | | | | The concept of these requirements is simple. At |
| OSHA standards, it can be used as evidence of | | | | each location, the arc flash study is used to |
| whether an employer acted reasonably in | | | | determine: |
| complying with OSHA standards and addressing | | | | - The incident energy exposure for a worker's |
| "recognized hazards”. | | | | chest and face if an arcflash occurs. |
| There are more specific links within the OSHA | | | | . The level of PPE a worker must wear based on |
| standards as well. A typical example is found in | | | | The possible incident energy exposure. |
| 1910.335, Safeguards for personnel protection | | | | . The arc flash protection boundary. |
| which requires: | | | | NFPA 70E provides generalized hazard risk tables |
| "(a)(1)(i) Employees working in areas where there | | | | that can be used as a simplified alternative for |
| are potential electricalhazards shall be provided | | | | PPE selection. This information, as well as data |
| with, and shall use, electrical protective | | | | regarding electric shock protection and approach |
| equipmentthat is appropriate for the specific parts | | | | limits, is used as part of an electrical safety |
| of the body to be protected and forthe work to | | | | program. |
| be performed. | | | | Before conducting live work, a qualified worker |
| This regulation requires that employees must be | | | | must perform the shock hazard and flash hazard |
| properly protected from potential electrical | | | | analysis that NFPA 70E requires. |
| hazards, by using adequate PPE, but it does not | | | | |