As an electrical engineer, I love digging into details. Usually the more specific I am, the less chance for a mishap. But for contractors in the field, complexities within the electrical code can be difficult to address.
In 2002, Section 110.16(A) was adopted into the National Electrical Code (NEC) to address arc flash awareness via a simple label warning of arc energy dangers. But, in my opinion, it didn’t go far enough. So, during the last code review, 110.16(B) was introduced to advise of the electrical hazard and provide guidance in selecting required arc-rated personal protection equipment (PPE) for justified energized work. However, Section B has caused some controversy as public input calls for even greater levels of detail to help determine proper safety apparel with greater ease when on a job.
Why does proper PPE matter? Jim Dollard, NFPA 70E committee member and International Brotherhood of Electrical Workers (IBEW) Local 98 representative, says it best. “People are injured or killed not because they wear the wrong levels of arc-rated clothing but because they don’t wear any. And if you’re not wearing arc-rated clothing, you’re wearing fuel!”
PPE calculations: A tale of two methods
A contractor needs to complete an arc flash risk assessment before doing any justified energized work. There are two ways to accomplish this. The first is the table method, which uses basic parameters to quickly determine arc-rated PPE without calculation. The other is the incident energy analysis method that calls for Calories per centimeter squared (Cal/cm2) at a working distance based on data gathered from the existing system, including calculated fault currents and clearing times of overcurrent protective devices (OCPDs).
The NEC panel tried to compromise between the two methods, but in the process created some safety concerns. Section110.16(B) requires displaying voltage, short circuit current, clearing time and the date on the label. While I like this simplicity, there’s more to consider. The information listed easily incorporates into the table method but doesn’t account for line-side propagation, or when the 6-disconnect rule is used, and the worker is staring at energized exposed bus and the only protection is a utility transformer line-side medium voltage fuse. While the 110.16(B) changes were the best the NEC could initially offer for expanding incident energy requirements, I believe simplifying arc flash calculations is the next logical step.
The devil is in the details; while I might put a label on a device to identify a 40-Cal event, for example, the actual label in the positive text will tell you it’s a PPE Category Two at less than eight Calories. This disparity can make for an extremely dangerous difference. Contractors may often be under duress since many important details have not been considered. This could be an opportunity for future solutions to prevent or confirm that line-side propagation will not occur within these enclosures.
Saying “I do” to wearing the right protective gear
The challenge is getting people out of flammable clothing and into appropriate PPE through code guidance that’s easier to understand and implement. It starts by putting ourselves in a contractor’s shoes. Here’s an example I often use to highlight the issue. An electrician is called for an outage at a wedding reception. The bride’s not happy, the hotel has its reputation on the line, and the contractor’s the one who’s probably going to do justified energized work to get the facility back on line. He’ll look at the service equipment and find a simple label, or no label at all. Is he going to halt work to hunt for an electrical engineer who’ll identify the right gear to wear, or will he just do the job? Let’s hope he doesn’t dive right in… while foregoing any kind of arc-rated PPE.
Do I think that we should perform in-depth studies and calculations on everything? Speaking as a detail-oriented engineer that’d be great, albeit unrealistic. There’s value in both the table and engineering methods, and I’m confident a middle ground on the code – one that clarifies arc energy specifics and simplifies its use in the field – can be reached. I’m hopeful we’ll expand upon NEC 110.16 in a way that encourages workers to make it a part of their everyday work lives through easy-to-apply guidelines with acceptable levels of risk.
As an aside, I encourage you to visit donniesaccident.com. This real-life story of a 20-year veteran electrician who faced months of rehabilitation challenges after an arc flash event drives home the significance of PPE and underscores the importance of making code easier to implement.
Learn more – Eaton industry experts are providing their perspective on key aspects of the electrical codes that impact safety and operational reliability.
Thomas A. Domitrovich is an Electrical Engineer within Eaton’s electrical group with experience in engineering, sales & marketing, business development and product management. Domitrovich is actively involved with various electrical industry organizations and most recently focuses on the continued growth of electrical safety. Domitrovich is an author with a wide range of trade magazine articles including columns in two industry trade magazines focused on electrical safety.
He sits on NFPA Code Making Panel 2 for the continued development of the National Electrical Code (NFPA 70). He is also on the NFPA committee for the continued development of NFPA 73 and chairs various committees for other electrical industry organizations. Domitrovich is a LEED® Accredited Professional, a licensed Professional Engineer and holds a Bachelor of Electrical Engineering from Gannon University.