Standard Interpretations - Table of Contents|
| Standard Number:||1926.95(a); 1926.416(a); 1926.416(a)(1); 1926 Subpart K|
|OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.|
No employer shall permit an employee to work in such proximity to any part of an electric power circuit that the employee could contact the electric power circuit in the course of work, unless the employee is protected against electric shock by de-energizing the circuit and grounding it or by guarding it effectively by insulation or other means. [Emphasis added]In your scenario, the employees are exposed to the hazard of electric shock since, at the time they are doing the work, a determination that the circuit has been de-energized has not yet occurred. Therefore, under this provision, these employees must be protected against electric shock "by guarding [the part] by insulation or other means." When so guarded, under this provision, PPE would not be required to protect against the electric shock hazard.
Protective equipment, including personal protective equipment for eyes, face, head, and the extremities, protective clothing, respiratory devices, and protective shields and barriers, shall be provided, used, and maintained in a sanitary and reliable condition wherever it is necessary by reason of hazards of processes or environment, chemical hazards, radiological hazards, or mechanical irritants encountered in a manner capable of causing injury or impairment in the function of any part of the body through absorption, inhalation, or physical contact. [Emphasis added].Industry consensus standards can be evidence that there is a hazard for which that PPE is "necessary." While the NFPA 70E consensus standard has not been adopted as an OSHA standard, it is relevant as evidence that arc flash is a recognized hazard and that PPE is necessary to protect against that hazard.
(9) Selection of Personal Protective Equipment.NFPA 70E's Table 130.7(C)(9)(a), Hazard/Risk Category Classifications, referenced above, lists the task, "Work on energized parts, including voltage testing" and assigns it a "Hazard/Risk Category" of "1" or higher. Under Table 130.7(C)(10), that categorization triggers various PPE provisions, including non-melting clothing, flame-resistant clothing, and other protective equipment.3 Thus, NFPA 70E is evidence that the industry recognizes the hazard of arc flash, that this hazard is present when testing voltage, and that, when present, it is necessary for PPE to be used to protect the employee from it.
(a) When required for Various Tasks. When selected in lieu of the
flash hazard analysis of 130.3(A), Table 130.7(C)(9)
shall be used to determine the hazard/risk category for a task.
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(10) Protective Clothing and Personal Protective Equipment Matrix. Once the Hazard/Risk Category has been identified, Table 130.7(C)(10) shall be used to determine the required personal protective equipment (PPE) for the task.
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(A) Flash Protection Boundary. For systems that are 600 volts or less, the Flash Protection Boundary shall be 4.0 ft, based on the product of the clearing times of 6 cycles (0.1 second) and the available bolted fault current of 50 kA or any combination not exceeding 300 kA cycles (5000 ampere seconds). For clearing times and bolted fault currents other than 300 kA cycles, or under engineering supervision, the Flash Protection Boundary shall alternatively be permitted to be calculated in accordance with the following general formula:Once the risk of exposure is assessed, the employer must then provide PPE in accordance with the results of the analysis. NFPA 70E §130.3(B) states,
Dc = [2.65 x MVAbf x t]1/2
Dc = [53 x MVA x t]1/2
Dc = distance in feet from an arc source for a second-degree burn
MVAbf = bolted fault capacity available at point involved (in mega volt-amps)
MVA = capacity rating of transformer (mega volt-amps). For transformers with MVA ratings below 0.75 MVA, multiply the MVA transformer rating by 1.25
t = time of arc exposure (in seconds)
. . . The flash hazard analysis shall determine, and the employer shall document, the incident energy exposure of the worker (in calories per centimeter). . . Flame-resistant (FR) clothing and personal protective equipment (PPE) shall be used by the employee based on the incident energy exposure associated with the specific task. . . As an alternative, the PPE requirements of 130.7(C)(9) shall be permitted to be used in lieu of the detailed flash analysis approach described in 130.3(A).As provided in the last sentence of section 130.3(B), NFPA 70E also provides an alternative analysis to determine PPE requirements. If the task to be performed has a high probability of arc flash occurrence, the charts under 130.7(C)(9) and (10) can be used to determine the appropriate PPE. Section 130.7(C)(9)(a) states in part,
When selected in lieu of the flash hazard analysis of 130.3(A), Table 130.7(C)(9)(a) shall be used to determine the hazard/risk category for a task. The assumed short-circuit current capacities and fault clearing timed for various tasks are listed in the text and notes to Table 130.7(C)(9)(a). For tasks not listed, or for power systems with greater than the assumed short-circuit current capacity or with longer than the assumed fault clearing times, a flash hazard analysis shall be required in accordance with 130.3.Although this analysis uses a worst case scenario to determine the need for PPE, if the breaker has more than the assumed short-circuit current capacity or longer than the assumed fault clearing times, the charts will be of no use, and the flash hazard analysis under 130.3 would need to be done.
|Standard Interpretations - Table of Contents|
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