What action is prohibited regarding the trolley wires?

The action that is prohibited regarding the trolley wires is working under them while bare. This practice is dangerous because trolley wires typically conduct electricity at high voltages, and working beneath them without appropriate insulation or protective measures can lead to severe electrical shocks or electrocution. Electrical safety protocols dictate that workers must take precautions, including using proper gear and maintaining a safe distance from live electrical components.

In contrast, insulating trolley wires is a safety measure designed to prevent accidental contact and enhance protection. Testing their functionality and monitoring for faults are essential practices to ensure the safe and efficient operation of electrical systems and are generally permitted when done following safety protocols.