Currently, there is no "Law" requiring this. However you can still be sited by OSHA for noncompliance of a law that does not exist.
In response to an inquiry to OSHA?s stand on arc-flash hazards, Richard S. Terrill, the Regional Administrator
for Occupational Safety and Health, US Department of Labor for the Northwest Region at Seattle, concluded
the following:
?Though OSHA does not, per se, enforce the NFPA standard, 2000 Edition OSHA considers NFPA standard a
recognized industry practice. The employer is required to conduct an assessment in accordance with CFR
1910.132(d)(1). If an arc-flash is present, or likely to be present, then the employer must select and require
employees to use the protective apparel. Employers who conduct the hazard/risk assessment, and select
and require their employees to use protective clothing and other PPE appropriate for the task, as stated in
the NFPA 70E? standard 2000 Edition, are deemed in compliance with the Hazard Assessment and
Equipment Selection OSHA standard.?
Also See
http://www.reliabilityweb.com/art05/nfpa_70e.htm
I think it is just a matter of time (soon) before AHJ's are going to require this calc on the permit set just as they want to see to short circuit calc. Might be a nice nich industry to get into.
I also think that local cash strapped goverments (cities, counties) will incorperate this into local regs, so they can fine business that do not comply with this. Just think of how many panels in a city times $100 fine. This would fix a city budget without raising taxes.