Electronics Protection - September/October 2011 - (Page 10)
Revised Regulations and Best Practices Help Keep Workers Safe
Troy A. Miesse, Strategic Marketing, Industrial Enclosures Rittal Corp. The National Fire Protection Association (NFPA) 70E, Electrical Standards for Safety in the Workplace describes arc flash as a dangerous condition. According to the National Institute for Occupational Safety and Health (NIOSH), during an arc flash temperatures as high as 35,000°F have been recorded. In fact, a NIOSH study estimates five to 10 arc flash explosions occur every day in the US. In addition, injury can occur within a few milliseconds according to the National Electrical Contractors Association. Given the most recent change reflected in the 2011 National Electrical Code (NEC) and the fact that the Occupational Safety and Image courtesy of Cascade Labeling LLC Health Administration (OSHA) has started fining companies, arc flash continues to be in the forefront of our industry as a serious issue. The article proposes to 1) define arc flash, 2) provide an update on the applicable safety codes and standards, 3) outline best practices to keep workers safe and companies compliant, and 4) outline product solutions to prevent arc flash. There are five main codes, standards and regulations that address arc flash prevention and safety. They were developed through the National Fire Protection Association (NFPA), OSHA and the Institute of Electronics and Electrical Engineers (IEEE): • NFPA 70 (the NEC) – deals with labels for hazard awareness • NFPA 70B “Recommended practice for Electrical Equipment Maintenance” outlines the procedures and practices to be followed for OSHA compliance and safety when working on live equipment • NFPA 70E “Standard for Electrical Safety Requirements for Employee Workplaces” discusses a variety of issues, including personal protective equipment (PPE), safety programs, worker training calculating the degree of hazard and warning labels for equipment • OSHA Standards 29-CFR 1910-S, number 1910.333 focuses on the legal requirements of which employers need to be aware to guard against arc flash hazards. It sets general requirements for safe work practices, PPE and hazard analysis • IEEE 1584 “Guide to Performing Arc Flash Hazard Calculations” deals with calculating the size of the potential fault. These calculations provide a basis for the level of PPE that is required when examining or servicing equipment
An Update on Arc Flash
What is an Arc Flash?
An arc flash is the explosive release of energy that occurs when there is a phase-to-phase or phase-to-ground arc fault. The arc fault may be the result of unsafe work procedures such as a dropped tool or accidental human contact. Additionally, an arc fault may be caused by corrosion, insulation failure, conductive dust and contact by animals. Workers who are exposed to an arc flash sustain injuries typical to an explosion such as: burns, loss of sight, loss of hearing, broken bones, head injuries and shrapnel injuries.
What are Best Practices When Dealing with the Potential for an Arc Flash?
What are the Applicable Codes and Standards?
While little has changed in the past couple of years regarding regulations, the NEC is revised every three years. The 2011 revisions include an additional change to the wording regarding warning labels. While a change in wording seems minor, it does give reinforcement to the importance of arc flash hazards.
NEC 110.16 Arc-Flash Hazard Warning (REVISED)
The title was changed from simply “flash protection” to “arc flash hazard warning” because arc flash protection was not addressed in the previous requirement. The required field marking relates to a warning of potential arc flash hazards. This rule does not apply to individual dwelling units, but usually applies to equipment in a large building that contains multiple individual dwelling units. Service equipment is to be field-marked with the maximum available fault current and dated. Modifications that change the available fault current (AFC) require updated available AFC marking as well as the date the calculations were performed.
The only true way to prevent arc flash and protect your workers is to de-energize circuits before working on them. If it is not possible to de-energize, or if de-energizing introduces additional or increased hazards, such as stopping ventilation to a hazardous location, the following practices are critical to maintaining a safe and productive environment on the shop floor and in the field. Analyze the workplace for arc flash hazards by trained electrical safety professionals and perform a detailed hazard analysis. Ultimately, the employer is responsible for its employees’ actions and should know what they do and don’t do regarding safety procedures. OSHA 29 CFR 1910.269(a)(2)(iii) states: “The employer shall determine, through regular supervision and through inspections conducted on at least an annual basis, that each employee is complying with the safety-related work practices required by this section:” “Note: OSHA would consider that tasks that are performed less often than once per year to necessitate retraining before the performance of the work practices involved.” IEEE 1584 and NFPA 70E are the guidelines for conducting an arc flash hazard analysis and safety initiatives. Label all field enclosures to warn of arc flash hazards. The NEC requires warning labels to be placed on the outside of electrical enclosures to alert engineers and other personnel of the arc flash hazard inside the control panels. These warning labels need to be an industry standard symbol, at a minimum. A better option is to include the results from the arc hazard analysis on the label. For instance, a more detailed label could
September/October 2011 www.ElectronicsProtectionMagazine.com
Table of Contents for the Digital Edition of Electronics Protection - September/October 2011
Electronics Protection - September/October 2011
Crenlo Adds Rolling Transit Case to Lineup of Emcor Enclosures
Emerson Network Power Introduces Knurr DCM Enclosures for Nexus 7000 Series Switches
Evaluating the Opportunity for DC Power in the Data Center
An Update on Arc Flash: Revised Regulations and Best Practices Help Keep Workers Safe
Re-Designed Panelboards Proivde Savings for Hazardous Applications
MetCase Launches Retex Flat-Packed 19 Inch Wall Rack System
New SlimShield Two-Piece Board Level Shielding Offers Shield Heights Down to 0.060 inches
FrigoDynamics Launches Series of Two-Phase Heat Exchanger Coolers
Rogers Corp. Launches New Solutions for Thermal Management
SurgeX Space Savers Offer Maximum Protection with Minimum Footprint
Amphenol’s Expanded Neptune Connector Line Provide Better Environmental Protection
Calendar of Events
Electronics Protection - September/October 2011