In IEEE 1584, dated 2002, on page 6, fourth paragraph, last sentence – “Equipment below 240 V need not be considered unless it involves at least one 125 kVA or larger low impedance transformer in its immediate power supply.â€

Also on page 25, third paragraph, last sentence within the model and testing discussion – “The arc-flash hazard need only be considered for large 208 V systems: systems fed by transformers smaller than 125 kVA should not be a concern.â€

I am working on Arc flash study for a small electric cooperative. Majority of our transformers are below 125 kVA size. I was wondering if anybody is using this as an option for not considering the arc flash study results for transformer less than 125 kVA.

Any input would be appreciated.

Thanks

I'm also wondering the same thing. If you have a bank of three single phase overhead 100 kVA transformers at 208Y/120, is this to be excluded by IEEE 1584 because it is <240V and no single unit is >125 kVA, or is it to be included in analysis, even though <240V, because the bank is 300 kVA, which is greater than the 125 kVA threshold?