Every electrician I ask tell me different story
This is important since wire are very expensive
I am need to connect an air-condition rated 240 50 Amp 3 wires (2 hot and ground)

According to the NEC
Table 310.16 Allowable Ampacities of Insulated Conductors Rated 0 Through 2000 Volts, 60C Through 90C (140F Through 194F), Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried), Based on Ambient Temperature of 30C (86F)

Types RHW, THHW, THW, THWN, XHHW, USE, ZW

For 60C (140F) is 40 amp

And for 75C (167F) is 50 amp

What is this temperature? Is it the temperature in the attic where I put the wire?

Also from the NEC 2002 book
8 AWG THHN, 90C copper wire is limited to 40 amperes where connected to a disconnect switch with terminals rated at 60C. This same 8 AWG THHN, 90C wire is limited to 50 Amp

Can someone tell me if I can use 8 AWG THHN
My contact: Electrical contractor, Electrician Santa Monica CA, Venice CA, Mar Vista, Culver City Westchester CA
gil@amorelectric.com
310-699-9444

Thank you