Tyndale presents Arc Week: a unique, week-long educational look at the world of arc flash hazards through the lens of Shark Week. Join Scott Margolin – our dedicated technical expert by day and passionate shark enthusiast in his free time – for engaging, memorable parallels that bring important lessons about risk protection and PPE to life.
Catch it all: Season 1, Season 2, Season 3.
Arcs are clearly dangerous, but the question is, how dangerous? How do we determine how big a given arc, at a given set of energies, out of a given piece of equipment will be?
What is arc incident energy?
Arc incident energy is the potential magnitude of an arc flash. In other words, it’s the measurement used to determine how dangerous an arc flash could be.
There are several variables that determine arc incident energy including but not limited to: voltage, amperage, cycle time, arc gap, and the distance of the worker from the arc gap. In this episode, you’ll learn about commercial and industrial arc flashes coming from a “box” or a piece of industrial gear, which uses IEEE 1584 to calculate arc incident energy. IEEE Std 1584, Guide for Performing Arc-Flash Hazard Calculations, is a standard from the Institute of Electrical and Electronics Engineers (IEEE) that provides a method of calculating the incident energy of arc flash event. This calculation takes place in a standard NFPA 70E environment.
Breaking down the impact of arc incident energy variables.
Starting with voltage and amperage, we explore what impact these variables have on the arc incident energy to better understand the danger workers that are exposed to a potential arc flash hazard could face.
- Voltage: For an arc flash to happen, the source needs enough voltage to sustain the arc flash while in air past one cycle (1/60 of a second). After that, as voltage goes up, the arc incident energy level doesn’t necessarily go up. So how much voltage is enough to conduct an arc flash? NFPA 70E covers arc flash protection starting at 50 volts. However, arc flashes are unlikely to sustain in air at that voltage, IEEE 1584 starts at 208 volts. At 208 volts and above, arc flashes are likely to sustain in air for long enough to ignite flammable clothing and cause second degree burns, or worse. Scott stresses the importance of understanding that low voltage is considerably more dangerous than most people realize. In fact, 480 volts is the number one problematic voltage for arc flash injuries in the United States.
- Amperage: Amperage is a very important variable to consider when working energized because amperage is interrelated to the incident energy level of an arc. If the amperage doubles, the incident energy level doubles. What does this mean for workers? As the amperage of the source increases, the more dangerous the work environment.
We’re not finished covering the variables that determine arc incident energy! Please join us tomorrow at 2PM EST to catch Episode 2: Return to the Danger Zone – Determining Arc Flash Energy Part 2. Follow along as Scott covers the remaining variables that determine arc incident energy. While drawing parallels to Top Gun’s Final Dogfight scene, you’ll learn:
- Why longer cycle times of an arc translates to a higher arc incident energy level.
- Plus, how arc gap is like the teeth of a shark, and why – like with sharks – the closer you are to an arc, the closer you are to the danger zone.
Do you have a flash fire – rather than an arc flash – hazard? The hazards may differ, but the valuable lessons in this series are relevant to workers in oil and gas and other industries that rely on PPE to protect workers from thermal hazards. Stay tuned in!