The required support distance for exposed vertical rigid metal conduit (RMC) risers from industrial machinery or fixed equipment, where the RMC is made up with threaded couplings, the conduit is supported and securely fastened at the top and bottom of the riser, and no other means of intermediate is readily available is ___.

Most states require an electrician to pass an exam to receive a journeyman or master electrician license.  State exams cover these topics:  Electrical Theory, Trade Knowledge, Grounding and Bonding, Wiring Methods and Installation, Overcurrent Protection, Load Calculations, etc.