Arc Flash NFPA 70E Webcast: Your questions answered
A recent Plant Engineering Webcast featured Brian Downie, Group Manager, Faith Technologies, on the topic: "Arc Flash University: The Latest on NFPA 70E: What’s new in arc flash protection." Downie responded to Webcast attendee questions that were unable to be answered during the Webcast. Those responses appear below.
An archive of the full webcast can be found here:
Q: What personal protective equipment (PPE) is required for the previous arc flash rating 0 with the new standard? Will repairs made before the new standard be grandfathered in, or will the repairs have to be made to conform to the new standard?
A: Minimally natural fiber garments such as cotton long sleeve shirts and pants along with safety glasses and hearing protection are all standard operating needs for basic electrical interaction on systems where we have arc flash levels that fall into the definition of what was called Category 0. That range still exists but the new codebook simply didn’t view it as a true "hazard" for arc flash. However, we still have a basic need on clothing that is mandatory.
Q: What constitutes a review of the arc flash program?
A: A review of an electrical safe work practice (ESWP) program involves a review of staff members, training requirements, plant electrical one-line diagram updates along with any engineering updates necessary to account for any changes in the program much like standard lockout-tagout (LOTO) annual audits.
Q: What are the specific requirements for arc flash labeling on devices and circuits less than 480v PPE needs when operating equipment with covers closed-earlier versions of NFPA 70e were not clear if PPE was still needed?
A: Voltages offer little indication of arc flash levels until you fall into the 120V conversation. Even 120/208V three phase can at times present real risk on arc flash.
Q: What are the label requirements in the absence of an arc flash study?
A: In summary, the codebook and OSHA have no alternatives on labeling. In either case a label shall be present to indicate voltage, and other safety ratings as necessary according to OSHA Sub Part S. It is difficult to estimate arc ratings based on the codebook tables.
Q: I would like to know a little more about the term "normal operation" per Table 130.7(C)(15)(A)(a) and "routing opening" per the definitions for disconnects and the minimum arc flash protection required in order to open or close a disconnect?
A: "Normal operation" of equipment is a routine part of LOTO and daily interaction from employees nationally. The goal each employer should have is to train staff on how to safely operate breakers and disconnect switches, which includes how to stand and also what potentially is needed on PPE for that closed door practice.
Q: Can you explain the deletion of Category 0 and no prohibited approach boundary?
A: Both of these topics are new in the 2015 NFPA 70E code release. Category 0 in concept has not truly gone away as the need for natural fiber garments is still required. My suggestion to employers is to remain consistent in their terminology, as people have gotten accustomed to over the past 15 years. The prohibited approach boundary was eliminated as the code committee felt it was redundant-meaning if you need your insulated gloves on at the 12" restricted boundary, then you already have protection in place, etc.
Q: What are best practices for reducing "dangerous" level arc flash hazard to level 4 or below on switchgear?
A: Unfortunately, in switchgear we are always dealing with the utility transformers creating high arc flash clearing times. The only clear option is to build an electrical system with the main breaker disconnect isolated from the rest of the switchgear sections, which allows you to isolate your main without having to include the power company at the same time eliminating any potential conflicts in how some people can interpret the definitions of "enclosure" and "overall risk." In short, if you install a new breaker ahead of your current system, the risk levels move to the new main and therefore the arc flash levels in the existing switchgear likely will fall to a HRC1 or HRC2 level.
Q: How about variable frequency drive (VFD) sources and 400Hz sources? Do the outputs of those devices require arc flash labeling? If so, what minimum KVA? The arc flash equations were developed at 60hz, so other frequencies are problematic.
A: You are correct in saying that the downstream side of drives is an issue on calculating risk levels! Often we find that companies formulate their best-anticipated level of HRC as that is technically all we can do there. The same situation applies to other unique applications that fall outside the quote "normal" electrical calculation ranges.
Q: A question on Article 130.2(A)4 about properly maintained meaning following manufactures recommendations. We’ve found that the manufacturer’s recommended maintenance is often not updated for current equipment and/or over cautious for facilities that do condition based and predictive maintenance. Does not following the manufacturer’s recommended maintenance schedule leave an opening for citation?
A: The goal to remember on maintenance practices is to do what you can to ensure proper function of the systems. My recommendation is to evaluate the age and type of equipment and simply build a program aimed at what types of tests are possible along with cleaning and exercising of the equipment. Aim your target on a 3 to 5 year rotation and you should be in good shape on a plan.
Q: So if the calculation method is used, is listing the PPE category on the label permitted?
A: Yes, if you perform actual engineering calculations on a complete system then those values take precedence over the task-based PPE selection methods in the codebook and you should always list the PPE category along with any other valuable information you feel is important for an employee to follow on a label. Remembering that the goal behind a PPE label is to offer guidance to an employee so they make good choices in the field.
Q: Does the arc flash study have to be done every five years?
A: That is an incorrect view of article 130.5. Be aware that OSHA and NFPA 70E have expectations that if a plant electrical system has changes that can affect the current PPE calculations, then it is a requirement to update your program. If you have made no changes, then the five-year concept comes into play, but only if you have absolutely no changes to the systems.
Q: What is a great reference source for making sure you are compliant with OSHA?
A: Unfortunately, there seems to be a ton of good resources out there, but there also seems to be a general lack of overall depth of support, meaning many resources tend to focus on one aspect of the topic such as engineering or the newest electrical equipment being made to circumvent arc flash issues. My suggestion is to stay focused on the fundamental goals of this topic, which involves staff training on good LOTO principles, how to use meters and PPE, and the value of good electrical one-line diagrams that can support LOTO. OSHA is interested in knowing your staff can achieve an "Electrically Safe Working Condition."