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9:27 pm
November 8, 2010
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Updating Your Electrical Safety Knowledge

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Avoid devastating accidents by following the safety steps and standards listed here.

Too often in the United States, a worker is severely injured or killed in an electrical arc-flash accident: That’s five to 10 times per day. Other electrical incidents can also harm workers. They typically involve accidental contacts with energized parts that lead to shock and electrocution. The injuries and fatalities resulting from these events can be devastating to workers and their families. The financial consequences can be very damaging to a company.

There are important steps that companies can take to reduce the occurrence of electrical accidents and better protect the worker and the employer from the physical, financial and statutory consequences of such incidents. This article covers nine steps for reducing your arc-flash risk. Several of them are required as part of the National Fire Protection Association (NFPA) standard 70E® 2009—which provides a detailed reference for facilities to meet the requirements of electrical workplace safety. The other steps are recommended and considered best practices for improving overall safety within a facility. Clearly, the fundamental requirement for electrical safety is always to place electrical equipment in an electrically safe condition whenever possible through a proper lockout/tagout procedure. But NFPA 70E 2009 provides additional best practices for electrical safety, and these are recognized and enforced by OSHA.

NFPA requirements

  • Establishing an electrical safety program with clearly defined responsibilities
    This is a written document created by the employer that covers all areas of the company’s electrical safety policies. It includes such things as lockout/tagout procedures, internal safety policies and responsibilities for electrical safety.
  • Conducting an electrical-system analysis to determine the degree of arc-flash hazard
    This analysis is an electrical-system study performed by engineers familiar with the power distribution and control equipment and the calculation methods required. The arc-flash analysis will determine, among other things, the incident energy potential of each piece of electrical distribution equipment in the facility. This incident energy potential will define the Hazard/Risk Category of personal protective equipment (PPE) that the employee is required to wear while performing any work when energized parts are exposed. The methodology for conducting these analyses is outlined in IEEE 1584 Guide for Performing Arc-Flash Hazard Calculations.
  • Using Task Tables 130.7(C)(9) to select PPE
    One alternative to a detailed arc-flash analysis that is permitted in NFPA 70E 2009 Article 130.3 Exception Number 2 is to use the task tables in 130.7(C)(9) to determine the required PPE Hazard Risk Category.

    Each table has usage limitations as stated in the footnotes. The footnotes typically specify a range of available fault current and clearing time for the upstream over-current protective device beyond which the tables may not be safely used. Unless a detailed arc-flash analysis has been performed, users will usually not know these details, and this commonly leads to misuse of the task tables, which can lead to under-protection for the worker.

    The task tables are based on calculated values within the limits of the stated footnotes, but also include the probability of causing an arc flash based on the task being performed. This probability factor is highly variable and subjective, and can potentially lead to significant under-protection.

    Since the NFPA 70E 2009 Article 130.3(C) now requires that the equipment be labeled with either the incident energy in calories per square centimeter or the PPE hazard Risk Category, using the tables creates a problem with labeling as well. Relying on a detailed arc-flash analysis for PPE selection is always a preferred and more accurate method.

  • Conducting safety training for all workers
    NFPA 70E defines a qualified person as “one who has skills and knowledge related to the construction and operation of the electrical equipment and systems, and has received safety training to recognize and avoid the hazards involved.”

    This training requirement means that the employee must have received safety training specific to the hazards of arc flash, arc blast, shock and electrocution. OSHA does not consider electrical workers to be qualified until they have received this specific training.

  • Ensuring there is adequate personal protective clothing and equipment on hand
    Employees working in areas where there are potential electrical hazards shall be provided with electrical protective equipment that is appropriate for the specific parts of the body to be protected and for the work to be performed. This can include fire-resistant shirts, pants or coveralls, or a multi-layer flash suit.
  • Ensuring proper tools are on hand for safe electrical work
    In addition to PPE, the standards require the employer to furnish other tools for safe electrical work. This includes insulated voltage-rated hand tools and insulated voltage-sensing devices that are properly rated for the voltage application of the equipment to be tested.
  • Applying warning labels to all equipment
    Currently, NFPA 70 dated 2008 (National Electric Code) states in Article 110.16 – Flash Protection: “Electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling occupancies and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.”

    The current NEC requirement for application of hazard warning labels on electrical equipment, National Electrical Code (NEC) 2008, does not require that the specific information, such as the PPE Hazard/Risk Category, incident energy, boundary distances and other data that would be provided by the arc-flash hazard analysis, be included on the label. However, the current NFPA 70E 2009, in Article 130.3(C), has elevated the labeling requirement by stating “Equipment shall be field marked with a label containing either the incident energy or required level of PPE.”

Additional best practices

  • Appointing an electrical-safety program manager
    Identify someone from your organization who has vast knowledge and experience within the electrical industry. This should be a well-organized, responsible individual who will take the position seriously. Having a single person who is familiar with electrical code requirements and other safety issues will pay off.
  • Maintaining all electrical distribution system components
    All electrical distribution systems contain active components such as fuses, circuit breakers and relays to help protect the system in the event of an electrical fault. While these components—called over-current protective devices—play a critical role in protecting the system, they’re crucial in protecting workers from arc-flash and arc-blast hazards.

    Modern, properly adjusted over-current protective devices that have been well maintained are able to detect an arcing condition almost instantaneously and clear the fault quickly. This always results in a significant reduction of the amount of incident energy that’s released. Many existing electrical distribution systems have old components that haven’t been well-maintained over time. In actual field testing, it’s often apparent their ability to react to an arcing event is much slower than would be the case with a modern, well-maintained device. Unless the protective device optimally reduces the time to clear the fault, the hazard to a worker standing within the flash-protection boundary can dramatically increase. In the past, the maintenance and condition of these devices was not a primary concern for many facility owners, as it often was not clearly understood that poor condition or inadequate maintenance presented an elevated safety hazard for workers. With the current focus on workplace hazards and electrical safety, companies are more vigilant regarding the condition and maintenance of their electrical systems. This requirement for maintenance of electrical distribution equipment has also been incorporated in the NFPA 70E in 2009.

  • Maintaining and updating electrical distribution documentation
    Electrical distribution system documentation is another important area that’s not been well-managed in many facilities. Documents such as the electrical one-line diagram (essential to safety when performing the lockout/tagout process), short circuit and coordination studies and other critical documents often are poorly maintained. When system components change due to revisions or facility expansions, this documentation is frequently not updated. Lack of attention to documentation management makes the cost and work scope of providing accurate arc-flash hazard analysis much greater. Since these documents are such a critical part of electrically safe work practices, lack of attention creates additional legal liability if an accident does occur. MT
For more info, enter 02 at www.MT-freeinfo.com

Joseph Weigel is a product manager for Square D Services, a business unit of Schneider Electric, and has been very involved in the development of Schneider’s Arc Flash Safety program to educate customers on emerging safety standards. He’s a member of the National Fire Protection Association (NFPA) and Institute of Electrical and Electronics Engineers (IEEE). Telephone: (615) 844-8656; e-mail: joseph-h.weigel@us.schneider-electric.com


Yes, Safety Really Does Pay

Schneider Electric North American Operating Division can attest first hand to the fact that safety really pays! Since 2003, the organization has reduced its medical cases by over 72% in North America.

Moreover, its current estimated Workers’ Compensation savings are $10 million for the 2010 calendar year.

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