
Thermoplastic
Flame-retardant, moisture-resistant
Flame-retardant, moisture and heat resistant
Flame-retardant and heat-resistant
Thermoset
Flame-retardant
Flame-retardant, heat-resistant
Thermoplastic and thermoset plastics encompass a large number of insulation classes in use
today with power and control conductors. They include insulation type letters MTW, RHH,
RHW, RHW-2, SIS, THHN, THHW, THW, THW-2, THWN, THWN-2, TW, XHH, XHHW,
and XHHW-2. The -2 suffix designation indicates the cable is permitted to be utilized at
a continuous 90
C (194
F) operating temperature in wet or dry conditions. Reference NEC
Table 310.13(A) for an explanation ...