Final answer:
The largest fuse protection for a 12 THHW copper wire at an ambient temperature of 110 degrees F would be 20 amps.
Step-by-step explanation:
To determine the largest fuse protection for a 12 THHW copper wire at an ambient temperature of 110 degrees F, we need to consider the safe current limit for the wire. Fuses and circuit breakers are used to limit excessive currents in order to prevent wires from overheating. Let's assume that the safe current limit for the wire is 80% of the wire's current capacity.
A 12 THHW copper wire typically has a current capacity of 25 amps. Therefore, 80% of 25 amps is 20 amps. Hence, the largest fuse protection for the wire would be 20 amps.