A client wants to install a new dedicated 240V, 30A circuit for an electric vehicle (EV) charger in their garage. The charger is located 80 feet from the main service panel. Assuming THHN conductors in conduit and a maximum voltage drop of 3% for the branch circuit, what is the minimum acceptable conductor size (AWG) that should be used?

Correct answer: C. 8 AWG

Calculations for Voltage Drop: 1. Max allowable voltage drop = 3% of 240V = 7.2V. 2. Formula for single-phase voltage drop: VD = (2 * K * I * L) / CM, where K for copper is 12.9 (CEC Chapter 9, Table 8). 3. Rearrange to solve for CM: CM = (2 * K * I * L) / VD. 4. Current (I) = 30A. Length (L) = 80 feet. 5. CM = (2 * 12.9 * 30A * 80 ft) / 7.2V = 61920 / 7.2 = 8600 CM. 6. Referring to CEC Chapter 9, Table 8 (Conductor Properties), we find: - 10 AWG: 10380 CM - 8 AWG: 16510 CM - 6 AWG: 26240 CM - 4 AWG: 41740 CM. Since we need at least 8600 CM, 10 AWG (10380 CM) would technically meet the CM requirement based purely on voltage drop. However, an EV charger is a continuous load, so the 30A circuit breaker must be sized at 125% of the continuous load (30A * 1.25 = 37.5A). A 30A breaker is typically used for 10 AWG (rated for 30A, but need to consider 125% for continuous loads). For 37.5A, the next standard OCPD is 40A. A 10 AWG conductor is only rated for 30A (CEC 310.16 at 75°C). So 10 AWG cannot carry 37.5A. The next size up is 8 AWG, which is rated for 50A (CEC 310.16 at 75°C), and its CM is 16510, which is well above the 8600 CM calculated. Therefore, 8 AWG is the minimum acceptable conductor size when considering both ampacity and voltage drop for a continuous load.