THW insulation has a _____ rating when installed within electric-discharge lighting equipment, such as through fluorescent luminaires.
a) 60°C
b) 75°C
c) 90°C
d) 105°C
See answer and applicable Code reference
The correct answer is: c) 90°C
Conductor construction and application rules are outlined in Table 310.104(A) through Table 310.104(E) of the 2011 NEC. As noted in Table 310.104(A), THW insulation has a 90°C rating when installed within electric-discharge lighting equipment.