GPD_Steve wrote:
Using the calculations methods of IEEE 1584 I have calculated energy levels much higher than what is listed in the table (ecspecially for 480V, pad mounted transformers). I see this table as being at best, a bare minimum for energized work.
Just got my hands on the 2012 NESC. I agree with your comments about 480V pad-mounted transformers having much higher energy levels when using IEEE 1584. This table is quite a change from the 20 cal per cm2 in the proposed table.
Footnote 9 indicates the following,
"Industry testing on 480 V equipment indicates exposures on pad-mounted transformers do not exceed 4 cal/cm2. (See Eblen and Short [B31].)"
I guess I need to read the referenced Eblen and Short article (
Arc Flash Testing of Typical 480V Utility Equipment) to understand how they came to this conclusion.
I suspect there is enough differences in the IEEE 1584 test enclosures physical layout and spacings compared to typical utility pad-mounted transformer cabinets to make the IEEE 1584 calculations not applicable.