NEC 410.4(C) addresses lights in kitchen range hoods. Here are pics of a lighting system that manage to violate every single provision of the code.
While the code does say "commercial,' and is silent on the subject of residential cooking hoods, I would expect these provisions to apply: -temperature limits of materials used not be exceeded; -cooking vapors excluded from wiring components; -exposed parts arranged so as to not collect deposits; and -wiring not to be exposed within the hood.
This section also brings up another interesting detail: the co-ordination of codes between different organisations. In this case, the NEC section, as well as the appropriate UL standards, were strongly influenced by the NSF (National Sanitary Foundation), which certifies equipment as suitable for commercial food industry use.