I hope the OP did not try to run UF cable through conduit! I think that would be almost impossible to pull through any significant length of 3/4 inch conduit. If you see this post, let us know what you ended up installing.
For anyone who comes across this post in the future, be aware that almost all, if not all, building wire sold these days in the US is dual rated THHN/THWN-2 so this wire can be used in locations that are considered "wet", such as wire that is installed in conduit that is installed underground.
THHN/THWN-2 wire has insulation that is rated 90˚C, however wire that is 14 AWG to 1 AWG is assumed to be connected to equipment terminals which are limited to 60˚C, unless such terminals are otherwise described, But most residential circuit breakers, NEMA receptacles, and the Tesla Wall Connector have 75˚C terminals therefore they use the 75˚C ampacity rating with THHN/THWN-2 wire. However, if you are using NM cable (a/k/a Romex) you need to use the 60˚C ampacity ratings for this type of wire/cable.
THHN/THWN-2 wire cannot use the 90˚C ampacity ratings for the circuit's capacity because no equipment that is rated for 600 volts (or less) is made that will support 90˚C terminations. But the 90˚C rating of this type of wire can be used for derating as described below in this posting.
So the temperature to which the conductors are exposed must also be taken into consideration. For a temperature of 120˚F the 90˚C column can be used, which is 40 amps for #10 AWG wire, and the capacity of the wire must be derated by a factor of 0.82 for this temperature, resulting in a capacity of 32.8 amps for #10 wire, so it is still fine to use #10 CU THHN/THWN-2 wire as long as it is protected by a 30 amp over current protection device.
Had the temperature the wire is exposed to been 140˚F, a derating factor of 0.71 would need to be used, resulting in #10 CU wire having a capacity of only 28.4 amps, requiring upsizing the wire to #8 CU to get a circuit that is rated at 30 amps or more and adequate for 24 amps continuous charging after derating by 80% due to the continuous use of EV circuits. (50 amp #8 wire x 0.71 = 34.5 amps.)
Unless the wire is run across a roof, at just an inch or so above the roof, almost all locations in the US are rated at 94˚F or less for derating purposes. The formula for calculating the temperature is complex; it is not the maximum temperature encountered. More details can be found at
www.copper.org.
Even though the Wall Charger will be charging the car at 24 amps, it requires a circuit to have an ampacity of at least 30 amps, *after derating*. A circuit that has only 28.4 amps of ampacity due to temperature derating would not be sufficient for 24 amp charging.
Most installations can ignore needing to be derated for temperature. If you have any doubts, you need to consult a licensed electrician. But having knowledge of this can help you to understand why an electrician might specify wire that is upsized for your particular situation.
