Arc Flash Three-Single Phase Multiplier

[DistCoop]

I've run across a few multipliers in converting single phase arc flash energy to three phase, and vice versa. ARCPRO gives a range of multipliers, the most conservative being three phase energy is equal to 2.2 times single phase. Duke Power suggests that the factor is 2.8.

Any idea where these came from? Is there a reference out there that may explain how they were derived, and why different companies/software vendors will use different factors?

Thanks for the help

 

[dpc]

You'll have to talk with the ArcPro people. I think they pulled them from a dark place. In the new OSHA rules, the commentary indicated that OSHA did not find much justification for these factors either.

 

[wbd]

If you have ArcPro, there is a paper contained on CD2 that discusses the multipliers and provides newer multipliers, that were developed based on IEEE 1584 test data, than are contained in the Help section of the software. This paper is dated July 18, 2008 so development of the OSHA regs were well under way and it may have been too late for OSHA to consider.