Hi All,

Is there a mistake in the IEEE 1584:2018 Annex D example for medium voltage? The results don't appear correct when calculating the Incident Energy and Arc Flash boundary using the reduced arcing currents (Step 11 and Step 13).

For example, if using the formulas shown as per Annex D, consider the following example which is just inside the 0.6 to 2.7kV Voltage band.



Results are calculated as follows:


But then re-run the calculation at 0.6kV level (just 1V less) using the <=600V formulas, and the reduced arcing current incident energy and boundary increase significantly:

Results are calculated as follows:


So, if the medium voltage equations in step 11 and 13 are modified to use (k3 x Iarc_600) instead of (k3 x Iarc_600_min) - and likewise for the other intermediate values. The medium voltage results start to look much more normal.
E.g. Re-running the original 0.601V example with these modified intermediate incident energy and arc flash boundary formulas, it yields the following results:

So is there a mistake in the formulas in Annex D?

Yes, I came to the same conclusions as you have some time ago. The fact is that the last time that I checked, which is some months ago now, at least one of the mainstream software manufacturers were interpreting the formulae for >601 volts literally which would lead to the same results that you have experienced. It is of course, up to the IEEE to acknowledge the anomaly and put it right. That being the case, you are correct and the 4.16kV Annexe D example is a mistake.

I think I found the same error.

For the intermediate energies, and AFB, I use Iarc_600 on the top, not Iarc_600_min. I still use Iarc_600_min on the right. This applies for the other intermediate values as well. See attached image.

How do I confirm with IEEE that this is the case?