When equipment listed for charging electric vehicles requires ventilation for indoor charging and is supplied by a 60-amp branch circuit and operates at 240 volts three-phase, the minimum mechanical ventilation for the total number of vehicles that can be charged at one time is ___ cfm.

When equipment listed for charging electric vehicles requires ventilation for indoor charging and is supplied by a 60-amp branch circuit and operates at 240 volts three-phase, the minimum mechanical ventilation for the total number of vehicles that can be charged at one time is ___ cfm.

• A. 444
• B. 512
• C. 296
• D. 854

Answer: (B)

Ventilation is sized to remove the heat produced by charging equipment. The more electrical power you can put into the vehicles at once, the more heat the room generates, so the ventilation has to keep up with that heat load. In this scenario, a 60-amp, 240-volt three‑phase supply yields about 25 kW of available power. If each charging port contributes about 6.25 kW of heat when in use, you can support roughly four vehicles charging at the same time before the heat load exceeds the capacity. The standard used here assigns 128 cfm of ventilation per vehicle to handle that heat. Multiply by four vehicles and you get 512 cfm as the minimum mechanical ventilation needed. If fewer vehicles are charging, the required cfm would scale down accordingly. The other options don’t match the four-vehicle, 128 cfm-per-vehicle calculation that aligns with the given electrical capacity and the per-vehicle ventilation rate, so 512 cfm is the correct total.

Ventilation is sized to remove the heat produced by charging equipment. The more electrical power you can put into the vehicles at once, the more heat the room generates, so the ventilation has to keep up with that heat load. In this scenario, a 60-amp, 240-volt three‑phase supply yields about 25 kW of available power. If each charging port contributes about 6.25 kW of heat when in use, you can support roughly four vehicles charging at the same time before the heat load exceeds the capacity. The standard used here assigns 128 cfm of ventilation per vehicle to handle that heat. Multiply by four vehicles and you get 512 cfm as the minimum mechanical ventilation needed. If fewer vehicles are charging, the required cfm would scale down accordingly. The other options don’t match the four-vehicle, 128 cfm-per-vehicle calculation that aligns with the given electrical capacity and the per-vehicle ventilation rate, so 512 cfm is the correct total.