Shock Risk Assessment Overview

OSHA 1910.132 (d) and 1926.28(a) states that the employer is responsible to assess the hazards in the work place, and to select, have and use correct PPE and document the assessment.

Is a requirement to issue Energized Work Permits and justify performing work on energized electrical equipment.

Shock Risk Assessment is determined by qualified personnel using guidelines, calculations and the tables required for the application. It is not expected that an employee not specifically trained to calculate arc flash incident values be required to do so, however it is expected that they can read and understand the information provided on an arc flash label.

How is the PPE required determined?

First, there must be an Arc Flash Risk Assessment to determine if an arc flash hazard exists and if there is, the following are determined:

  • appropriate safety related work practices associated with the equipment
  • the arc flash boundary for the area affected
  • and the PPE requires to be used within this boundary

There are many methods, software programs and companies providing this service, the two that are widely used are:

IEEE 1584 Arc-Flash Hazard Calculation, "Guide for Performing Arc-Flash Hazard Calculations." which contains detailed methods, steps and data that can be used to calculate Arc-Flash Hazards for electrical systems.

 

NFPA 70E Article 130 Annex D, Incident Energy and Arc Flash Boundary Calculation Methods contains information on several methods used to calculate incident energy and arc flash boundaries.

 

There is a third method used if the criteria in the standards are met:

NFPA 70E 2015 Table 130.7(C)(15)(a) for AC systems and NFPA 70E 2015 Table 130.7(C)(15)(b) for DC Hazard/Risk Categories, Table Method - an alternative method which uses tables with various tasks to be performed on energized electrical equipment to assess Hazard Risk Categories and the proper PPE required. This is not a replacement for a complete Flash Hazard Analysis and may only be used in some applications. It is subject to specific provisions as specified in the articles.

 

A significant revision in the NFPA 70E 2015 update states that the arc flash boundary distance is to be calculated for all locations where the voltage is 50 volts or more and there is a possibility of a worker performing energized work such as maintenance, diagnostics and testing being exposed to an arc-flash risk.

 

NFPA 70E Article 100. Definitions.

Risk. A combination of the likelihood of occurrence of injury or damage to health and the severity of injury or damage to health, that results from a hazard.

Risk Assessment. An overall process that identifies hazards, estimates the potential severity of injury or damage to health, estimates the likelihood of occurrence of injury or damage to health, and determines if protective measures are required.

  • Informational Note: As used in this Standard, "arc flash risk assessment" and "shock risk assessment" are types of risk assessments.

 

Electrical_Panelboard_and_Transformer_Requiring_Arc_Flash_Labeling.jpg  

Figure 1: Electrical Panelboard and Transformer Requiring Arc Flash Labeling

Courtesy of Dean Thomas, GTRI

 

NFPA 70E 2015 Article 130.5 Arc Flash Risk Assessment.

An arc flash risk assessment shall be performed and shall:

(1) Determine if an arc flash hazard exists. If an arc flash hazard exists, the risk assessment shall determine: a. Appropriate safety-related work practices b. The arc flash boundary c. The PPE to be used within the arc flash boundary

(2) Updated with major modifications and reviewed periodically, at intervals not to exceed 5 yrs.

(3) Take into consideration the design of the overcorrect protective device and its opening time, including its condition of maintenance.

Informational Note No. 1: Where equipment is not properly installed or maintained, PPE selection based upon incident energy analysis or the PPE category method may not provide adequate protection from arc flash hazards.

Figure 2: NFPA 70E 2015 Article 130.5 Arc Flash Risk Assessment