Final answer:
Class 1 conductors 18 and 16 AWG suitable for 600 V use must have insulation that meets the specifications of the National Electrical Code to protect against shock and thermal hazards.
Step-by-step explanation:
The insulation requirements for class 1 conductors 18 and 16 AWG that are suitable for a 600 V application can be found in the National Electrical Code (NEC). These conductors should be insulated to withstand a voltage of 600 V to protect against shock and thermal hazards. The specific type of insulation required can vary, but typically these conductors are insulated with materials like PVC, Teflon, or rubber, which are rated for their temperature and electrical properties to ensure safety. The insulation is critical in electrical safety as it prevents direct contact with the live wire, thereby reducing the risk of electric shock, and also provides a barrier against the heat generated by the electrical current.