The 2021 edition of NFPA 70E Informative Annex D contains information about incident energy and arc flash boundary calculation methods.

However, since the equations from the 2018 Edition of IEEE 1584 are so complex and require many “K� values from tables, only a general discussion is provided and the equation details were omitted.

The Ralph Lee equations from the 1980’s are provided as well as equations from the late 1990’s paper by Doughty, et al.

Sometimes people will default to the Lee equations for calculations outside the bounds of IEEE 1584.

This week’s question is to see if anyone uses the 20+ year old equations.

Here is this week’s question:

What calculation method(s) do you use from NFPA 70E Annex D for arc flash studies? Select all that apply
1980’s Ralph Lee equations
Late 1990’s Doughty equations
2002 IEEE 1584 (not in NFPA 70E)
2018 IEEE 1584 (equations not in NFPA 70E)
Something else

Although not mentioned in NFPA 70E Annex D, we also us Arcpro for voltages greater than 15 kV