My company does engineering for a major oil company and the 'Company' representative has stated that a 'certified' increased safety terminal block is required in a NEMA 4 X enclosure for termination of lighting conductors. His reasoning is that the 'not certified' terminal block might vibrate loose and cause a spark. He can't seem to find the rule in the code and I can find nothing to contradict him. I've never known of this requirement or utilized such a device. However, I'm 67 years old (in my days we used wire nuts) I guess changes could have been made to the code. Any help appreciated