In no way is NFPA 70E a part of NFPA 70. It is a totally separate document and is not enforceable by an AHJ. I don't even see it as an extension of NFPA 70E. They are not really related to each other. One is an installation code and the other is a safety standard.
You are correct. The NFPA 70E (Standard of Electrical Safety in the work place) is not part of NFPA 70 (National Electric Code). All states and communities have accepted the NEC as defacto standard code and in some cases enforce a bit stronger. Example of this is that some inspectors want recepticals with ground up and some down. As you said the NEC is code for installation and the other is just a safety standard. Osha only sites this as a reference and has no subparts that state that you need to run Arc Flash calculations or require labeling of your equipment. This is just a standard that one may follow. I personally following this standard and am currently using an outside engineering firm to collect data, calculate the correct Calories, help us select PPE and place labeling in 68 facilities within my corporation. Also I am having every maintence individual tested and must pass the test with a 70% to work on electrical equipment by themselves. The test part is because of OSHA 1926.32(M): "Qualified" means one who, by possession of a recognized degree, certificate, or professional standing, or who by extensive knowledge, training, and experience, has successfully demonstrated his ability to solve or resolve problems relating to the subject matter, the work, or the project. Yes I am in charge of spending a pretting penny on this.
A little bit on labeling. Yes the NEC now calls out for labeling on equipment. But this only pertains to new installations and is a very generic label. You do not need to go back and label equipment that was previously installed. Example of this is that the NEC calls for GFCI's in Kitchens. But unless you rewire or do work on the kitchen with a new installation then you do not need to put in GFCI's in a kitchen that was covered under a previous code. Same goes for NFPA 79 Electrical standard for industrial machinary. If a machine was wired in 1979 then you go by that code until you upgrade the machine. Then you need to bring the machine into compliance under the new regulations.
Now what OSHA will site you for is under the General Duty Clause. This is a $4500 fine for the first offence and may be in such a form as not having ppe available. This happened recently to one of my facilities. They wrote a PO very quickly to get under my umbrella with the AF program.
In another post someone put the link for an interpretation on AF from OSHA and it states basically that OSHA does not enforce. Here is another one that is newer. It basically states that you need to use PPE.
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25973
The following are links from OSHA?s website on fines dealing with Arc Flash.
Zap Electrical Contractors 2006 $1500
http://www.osha.gov/pls/imis/establishment.violation_detail?id=308619733&citation_id=01001
Bell Electrical Contractors 2006 $2500
http://www.osha.gov/pls/imis/establishment.violation_detail?id=309917524&citation_id=01001A
Anderson Sales and Salvage Inc. 2005 $2500
http://www.osha.gov/pls/imis/establishment.violation_detail?id=308999226&citation_id=01001
Van Ert Electrical Enterprises 2005 $4500
http://www.osha.gov/pls/imis/establishment.violation_detail?id=306798679&citation_id=01001
Kestrel Management L.P. 2005 $1375
http://www.osha.gov/pls/imis/establishment.violation_detail?id=307528547&citation_id=01001
Best in Plastics corporation 2003 $1125
http://www.osha.gov/pls/imis/establishment.violation_detail?id=304363559&citation_id=01001A
Showa Aluminum Corporation 2003 $4500
http://www.osha.gov/pls/imis/establishment.violation_detail?id=305434243&citation_id=01001
Now after my long winded statements and citings I have this to say about the original question.
It is the companies responsibilty to see that they self enforce themselves. OSHA is there to oversee and give interpretations and be the tie breaker or even be a reporting agency to file grievance to. OSHA is not the defacto standard and they themselves even offer up interpretations of their own documention. If you are fined by OSHA and do not put up a little bit of a fight then you or your company know that you did nothing to premote safety and it was time for a reality check. If you do fight OSHA then you are stating that you have done due diligance and fighting for your interpretation. In the end it is to premote safety.