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The latest revision of IEEE 1584 was released in 2002, and since then there has been much work on preparing and releasing a new version which with the increase in renewable energies and the necessary DC and larger capacitors, this new revision is greatly needed. But I’m getting ahead of myself.
IEEE 1584 2002 is
The Guide for Performing Arc-Flash Hazard Calculations published by IEEE Standards. This guide helps engineers, safety professionals, and manufacturers estimate the thermal energy that a worker would be exposed to in the event of an arc flash event. CSA Z462 and NFPA 70E both recognize this standard as an acceptable means of evaluating the risk associated to an arc flash hazard regarding the thermal energy.
IEEE 1584 Limitations
The 2002 version of IEEE 1584 does have some limitations, that at the made a lot of sense based on the installed electrical systems. They are:
- Short Circuit Current – 700 Amps – 106,000 Amps
- Three Phase Faults Only
- Frequency 50 Hz to 60 Hz
- Conductor Gap 13 mm to 152 mm
- Sinusoidal AC only
Looking at the installed electrical power system, specifically non-utility, these limitations appear pretty minor. The majority of the installed industrial systems (commercial and residential included) in the world are AC at 50 or 60 Hz. The only major exception might be aluminum smelting or other ore processing.
The majority of arc flash events start as single phase in a piece of equipment, but propagate to 3 phase within a cycle.
Most of the arc flash events happen within electrical equipment with the gaps less than 150mm.
So in 2002 this made a lot of sense. However, the world has changed a lot since then. There is way more large DC installations in the form of battery storage, and solar installations, and added large capacitor installations both for VAR support and short term energy storage. These two installations are not covered in IEEE 1584-2002 and have very different arc flash characteristics.
Over the last couple of years a lot of research has been done to try and reduce the impact of these limitations. The last two IEEE Electrical Safety Workshops have had great papers presented on determining the arc energy of impulse arcs from large capacitor banks, DC arcs and high frequency arcs.
You may have noticed above that I kept mentioning “thermal energy”, well that is all that IEEE 1584 allows you to determine, the output of the equations are a energy density. The other hazards associated with an arc flash event include:
- bright light
- they are loud
- physical and moving parts
The first two are pretty simple, but the physical and moving parts I will explain. You will read a lot about arc blast on the interwebs, and in reality its a red herring. There is no correlation between arc flash energy and arc blast energy. However, with the high currents during an arc flash event, there is a chance of cables and busbar whipping if they are not braced properly, and if the event happens at a height there is a fall hazard.
In 2015 there was a great paper presented where they were starting the development of a classification system that would take into account all the associated electrical hazards: A complete Electrical Hazard Classification System and its Application
Most of you will only be applying IEEE 1584 through the software you use to determine the arc flash incident energy, and won’t need to know the complete ins and outs of how the standard is developed. IEEE 1584 is the best calculation method we have and as it develops it will be a much more completed standard.
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There is a hierarchy of hazard mitigation that many people in the electrical industry don’t think about, either because of perceived cost, or complexity, or simply not knowing.
A hazard will always be a risk to the worker until it has been eliminated, and this is the goal in a perfect world. Design products and systems that remove the hazard completely. However, we aren’t there yet, so there is an industry standard to the way we look at a risk assessment, whether it is for electrical hazards, or any other hazard in the work place, and we lower the risk to the worker to an acceptable manner.
They are, in order of importance
How they are used
PPE is at the bottom