Where would one find info on the clearence required for a 4160 high voltage utilty line over the roof of a building(industrial) paper mill.There thinking of adding an Addition and the current line would run over the addition. Yes I know some well say contact the utilty company, But its gotta be somewhere.(located in michigan)

This is a lousy answer, but you can find it in Artlicle 234 of the National Electrical Safety code, but you have to know your cable type, wind load, etc to calculate.

Article 110 and 490 of the NEC do not really address any specifics of 4,160. OSHA is very concerned where there is access to the roof. Will there be equipment requiring service up there? If so, I suggest the minimum is 10 feet which is the minimum clearance for working unless trained, and properly PPE'd.

Hope this gives you an idea where to start.

clearances;225.60 Over 600v
230.24 not over 600v

FWIW, there is a regional 'NESC-like' document at ftp://ftp.cpuc.ca.gov/gopher-data/GO/GO95.pdf {2.5MB pp.441}