Arc flash hazard mitigation is at the top of every plant's electrical-system-safety list. Help ensure your electrical-system workers go home at night by understanding the risks and the latest technologies designed to minimize them.
During a recent webinar, Chief Editor Mike Bacidore spoke with Joe Weigel, owner of Electrical Safety Works, and Mark Ackerson, safety maintenance instructor for AVO Training Institute, about how regulations such as NFPA 70E impact the plant. Here are answers to your questions from that webinar.
Question: Is PPE required for resetting a breaker?
Answer: It really depends on the size of the breaker. In small, low-voltage (less than 480-volt) lighting and circuit feeder panels, with the panels dead front covers all in place, PPE is not necessary to switch or reset a circuit breaker. But power circuit breakers such as 600 Amps and larger at any voltage, it would be prudent to wear PPE. I would recommend PPE to switch any breakers that are 1000V AC or higher voltage.
Question: Besides PPE, are there any alternative methods?
Answer: Yes. Turn off all the power and lock it out. Once an "electrically safe work condition" is confirmed by a qualified person wearing PPE (no voltage) work can be done without PPE.
Question: What about remote racking and remote switching for "tools for safe work"?
Answer: Remote racking and remote switching are both very useful safety options, if these options can be utilized. Not all circuit breakers can be remotely operated unless they are electrically operated. Racking breakers always requires PPE unless the person doing the work is outside of the hazard area by using a remote racking device.
Question: Who can deem an employee qualified? This is in a maintenance setting.
Answer: The employer is responsible for making sure that the employee has been trained, that the training is documented in writing, and that the employee has demonstrated proficiency in working safely. The employer/supervisor determines who is qualified and is also responsible for that decision.
Question: Where is it written that a PE must perform the arc flash calcs?
Answer: As far as I know, there is no written requirement in the standards that state that only a PE can perform arc flash analysis. However, IEEE1584 says that a properly executed arc flash analysis consists of a combination of several electrical studies (short circuit study, time-current coordination study, and the arc flash analysis itself). Typically, only licensed electrical engineers are trained and capable of performing these studies, so the inference is that only licensed electrical engineers should perform these system studies. If someone is comfortable with doing this kind of work without being an EE or PE, and is willing to take the legal risk of doing it, doing so would not violate any written requirement.
Question: What is considered ''work''? Is simply opening a cabinet and looking inside considered work?
Answer: Yes. This is called "non-contact inspection" and PPE is required if the covers are removed or there are any exposed conductors or circuit parts. IR inspection falls into that category. Look at tables 130.7(C)(15)(a) in NFPA 70E and you will see some PPE recommendations for this kind of interaction.
Question: What is considered to be up to date on single line drawings?
Answer: The single line drawings are considered up to date if they show every change that has been made in the electrical system. If you replace, for example, a 225A circuit breaker with another 225A circuit breaker in a panel, that is not a change. If you add a safety switch or other device or add circuits or equipment, that will require the drawings to be modified to show those changes.
Question: New version of NFPA 70E does not mention date on the label. Why the change?
Answer: You are right! Article 130.5(C) describes what must be on the equipment label, and it does not show the date. It is common practice, however, for most engineering companies who do arc flash analysis to put the date of the AF analysis on the label. The feeling is that the date will indicate how recent the arc flash study is. The NFPA 70E requires the arc flash studies to be reviewed periodically, so the date could be useful in that regard.
Question: How do you make workers put on their PPE?
Answer: Management must understand and support the company's electrical safety policies. Employees must conform to those policies, including wearing PPE. Those employees who constantly violate the policy should be counseled and terminated if they continue to violate the rules. They are a liability to themselves, to the company, and to others.
Question: If commercial software is being used to determine the arc flash calculations, does a licensed professional engineer need to be the person entering the data in the program and running the program, or does it just need to be supervised by the licensed professional engineer?
Answer: There is a lot of judgment required, based on experience and training, that determines how to input the data into the software. Bad data in results in bad data out. An example is arc fault propagation in three phase systems. If the operator doesn't understand this phenomenon, they will make bad decisions. Often, a less experienced engineer will enter the data and run the calculations, but the results are reviewed and "stamped" by a more experienced engineer.
Question: How do you protect employees from complacency?