**NFPA and IEEE confusion**I think you cut to the heart of one of a very confusing issue. Back in 2004 shortly after the latest NFPA 70E was released, I wrote an article for the NEC Digest that was published at the begining of 2005. The article was intended to show the relationship between OSHA, NFPA 70E, NEC and IEEE 1584 fit together when it comes to electrical safety and arc flash. [url="http://www.brainfiller.com/documents/OSHANECNFPA.pdf"]Copy of PDF of NFPA/OSHA Article[/url] My draft was reviewed by the NFPAâ€™s top electrical safety person at that time. I was required to delete almost all references that I made to IEEE from the article including the title. I still have a copy of the reviewerâ€™s comments that explain the relationship (or lack of) between 70E and 1584. Iâ€™ve copied some of the review comments below (from 2004) that might help with all of this.

Here is a line from my original article that was required to be deleted:

â€śIn addition, IEEE Std.1584tm, IEEE Guide for Performing Arc Flash Hazard Calculations, contains the recommended practices for performing detailed arc flash calculations that can be used to determine the correct PPE for the amount of incident energy that could be available at a given locationâ€ť.

Here is the reviewerâ€™s response to the above paragraph:

â€śIEEE 1584 is a guide that is a possible method of performing arc flash calculations. IEEE 1584 was submitted in a proposal to be the only method of determining arc flash calculations. The committee rejected the proposal and chose to put the information in the annex. Annex information is informational and not an enforceable part of the standard which means it is not embraced by the committee. There are also other methods and examples in the annex from other sources.â€ť

I also had this paragraph in the article but was required to delete it:

â€śThe Institute of Electrical and Electronics Engineers (IEEE) has developed a standard known as IEEE Std.1584tm, IEEE Guide for Performing Arc Flash Hazard Calculations, which defines formulas and procedures used to calculate the amount of incident energy that can be released during and arcing short circuit.â€ť

The following statement was also made by the NFPA reviewer referencing a statement I made about using the IEEE 1584 formulas

â€śThe formula in the standard is the Ralph Lee formula. It is the only formula that is enforceable. There are formulas in the annex from different sources. None of them are recommended and are there for information only.â€ť

During the last IEEE 1584 meeting that I attended in September 2007, one of the people in the meeting that is on the NFPA 70E committee stated that the NFPA does not want to endorse other methods including IEEE and again referenced Ralph Leeâ€™s formulas. There was an immediate response from many people in the room about IEEE being based on more current research and models and why would someone want to use formulas that date back to the 1980â€™s.

There does seem to be some disconnect between NFPA and IEEE however this is presently being resolved. A joint collaborative effort has been formed between IEEE and NFPA to work together on the next generation of research and theory. This effort is presently underway with some collaborative tests (such as DC arc flash) already completed. I am hopeful that with both groups working together now, much of this confusion will finally be put to rest.

In the mean time, everyone I know that performs a detailed study uses IEEE 1584 so they can defend that they have used information based on more current research. Most of the major software manufacturers also base their programs on the IEEE methods (although some have other calculation methods as an option) Some utility based software such as ArcPro does use a physics based model which is based on a single phase arc flash.

So where does this leave us in regards to your question? For now, still confused.