Arc Flash Hazards - 1976 to Today
PUBLISHED IN THE FEBRUARY ISSUE OF "PFMA CONNECTION"
WRITTEN BY WALTER POWELL
MIDWEST ELECTRICAL TESTING
Everyone in the electrical power world is by now well aware of NFPA’s Bulletin 70E, now known to many simply as Arc Flash Hazard requirements. We receive calls everyday, from Engineers and Electricians, asking what they should be doing to comply. Unfortunately much of the marketplace is providing the answer as a "commodity." Just buy an "Arc Flash Hazard Analysis" and your problems, ie liabilities, go away. This approach ignores their immediate needs and ignores the other important "Chapters" and "Articles" of Bulletin 70E and ignores the critical part of an Arc Flash Hazard Safety Program, the "Implementation." The implementation is the major challenge. The engineering analysis without training and tools to implement the program fails the intent of OSHA, Title 29, Section 1910. Therefore what should one do? We suggest the following. But first, let’s lay the foundation for these suggestions.
How important are the Arc Flash Hazard provisions of NFPA? We have been in the electrical power business going on four decades and this is by far the most important safety development in that time. And it is long overdue. Why? In the past the main concern was avoiding electrical shock. Today the concern is to also avoid electrical "Burn" and "Blast."
An electrical arc may cause horrific burn damage to your body in a fraction of a second. The arc temperature could be hotter than the sun. The amount of injury depends on (1) The temperature of the arc, (2) How close you are to the arc, and (3) How long the arc lasts. Note, there are some short circuit protective systems that provide very poor protection from arcing faults. It could take 30 seconds to clear an arcing fault instead of a fraction of a second. And you could be several feet away and still be burned.
The blast from a sudden arc could injure you by knocking you down, off a ladder or platform, and could damage your ears, lungs and other internal organs. Fatal injury could occur.
Where did all this start? The National Fire Protection Association began work on NFPA Bulletin 70E in 1976 with the appointment of a committee on Electrical Safety Requirements for Employee Workplaces. In 1981 the 2nd Edition of the Standard included Part II, Safety-Related Work Practices. Over the years this Standard evolved and eventually became the 2004 Edition of NFPA 70E. NFPA is not a regulatory organization and this Standard was developed through the efforts of many volunteers "representing varied viewpoints and interests." Although NFPA 70E embodies many of the requirements of OSHA, 70E has not been adopted by OSHA per the procedures of section 6(b) of the OSHA Act. But, now that NFPA has presented to the public a written method of "reducing the risk of electrical injury" due to burn and blast, the legal world will expect a "reasonable person" to follow these methods or be liable for the consequences. In addition, OSHA Title 29, 1910.335(a) does require appropriate "electrical protective equipment."
What should you do? If you are a maintenance electrician working "on or near live parts," ie energized electrical equipment, at or under 240 volts AC, we suggest as a minimum you wear (1) 100% cotton underwear and undershirt, (2) 100% cotton long sleeve shirt and trousers or flame resistant shirt and trousers, and (3) safety glasses. If you are working around equipment over 240 volts, we suggest you also wear a pair of 8 cal/cm2 coveralls, a face shield, and a pair of good leather gloves. The gloves are not for shock protection. Does this comply with 70E? NO IT DOES NOT. Does this mean you can work on or near exposed energized equipment over 240 volts AC. NO IT DOES NOT. YOU MUST HAVE GREATER PROTECTION. It does not because you do not know how much fault current is available and how long an arcing fault would last. YOU DO NOT KNOW THE LEVEL OF RISK OR THE "FLASH PROTECTION BOUNDARY." Does this mean you are protected if you just don’t touch the energized parts? NO IT DOES NOT. You can not be exposed to the hazard of energized electrical parts. The suggested "Personal Clothing" (PC) and "Personal Protective Equipment" (PPE) is only a suggested minimum for work at 240 volts AC and less until a proper risk analysis is performed. Note, even the risk level at 240 volts and 120 volts could exceed the temporary minimum protection suggested above. You must not assume that following these suggestions in any way makes it safe to ignore NFPA 70E. In addition, you do not have the right to put yourself or someone else at risk of injury by assuming you are protected from a shock, arc burn or arc blast.
What should one do if you have to work on energized parts and you don’t have the results of an Arc Flash Hazard Analysis? Answer, You don’t! Turn the equipment off before servicing.
NFPA 70E covers more than Arc Flash Hazards. It has four chapters. Article 130 (Working On or Near Live Parts) of Chapter I is the critical section dealing with Arc Flash Hazards. The Chapter Titles are (I) Safety-Related Work Practices, (II) Safety-Related Maintenance Requirements, (III) Safety Requirements for Special Equipment and (IV) Installation Safety Requirements.
The purpose of NFPA 70E is to reduce the risk to a level that would prevent you from receiving a second degree burn or worse if a fault did occur. Determining the level of risk requires an Arc Flash Hazard Analysis. The basic features of the analysis are as follows: (1) Obtain the fault current available from the electric utility, (2) Collect information on the electrical power distribution equipment and protective system, (3) Prepare a one-line drawing, (4) Perform an Arc Flash Hazard Analysis, (5) Prepare labels to be attached to all the electrical devices in the power distribution system and on building and production equipment, (6) Prepare a "Required PC and PPE Document" and (7) Train personnel on the Arc Flash Hazard Program and the proper use of Protective Clothing (PC) and Personal Protective Equipment (PPE).
In summary, an Arc Flash Hazard Safety Program is a tremendous improvement in electrical safety. If you have some exposure, at least get the minimum PC and PPE until a risk analysis has been performed. But don’t assume the suggested PC and PPE protects you around energized exposed electrical equipment. It does not. If you must turn the power off to be safe, then you can not choose to do otherwise. You do not have the right to choose to be unsafe.