Yes, you're on the right track. The 600VDC used in subway systems can be dangerous if it comes into contact with water or creates a path for electrical current to flow. However, subway systems are equipped with various safety mechanisms, including ground fault protection, to prevent accidents. When there's a fault or leakage, these systems can quickly cut off the power to minimize the risk of electrocution and prevent the water from boiling due to electrical current passing through it. Safety measures like these are crucial for keeping subway passengers and workers safe.