The jurisdiction I work for has written it in the county code amendments. We try to limit the number of amendments and only have a few. An Electrician is required to install- 2 #12awg,steel wires from the structure to ,2 opposite corners of lay in lights. 1 #12 awg steel wire from the structure to recessed lights smaller then 24". Light boxes for in the ceilings for fire alarms devices, exit lights, surface mounted lights all require 1 #12 awg steel wire also.
Not in the NEC and our Fire Marshall pushed this so it's added as a local amendment.
