THHN/THWN-2, All Sizes
Single conductor building wire for conduit and raceways, with PVC insulation under a nylon jacket that pulls easily. THHN and THWN-2 are insulation types in NEC Table 310.4(1); their ampacity comes from Table 310.16.
We list 21 sizes of THHN/THWN-2, from 14 AWG to 1000 kcmil. All of them are priced online, from $0.1552/ft. Sold by the foot in whole feet from 25 ft, or on standard spools and coils. Up to 17 colors are listed per size. Each size has its own page with the price for every color and length, the date an order placed now ships, and the full specifications.
The ampacity column is from NEC Table 310.16, 75 C column, for not more than three current-carrying conductors at 30 C ambient.
The breaker column applies NEC 240.4(D): 15 A on 14 AWG copper, 20 A on 12 AWG copper and 30 A on 10 AWG copper (15 A and 25 A on 12 and 10 AWG aluminum).
Code references are to the NEC; check the edition your jurisdiction has adopted and any local amendments.