Besides to avoid people getting electrocuted, why do you wires have a plastic coating?
From the link given below: “Since air is an insulator, no other substance is needed to “keep the electricity within the wires.” However, wires which touch each other will produce cross connections, short circuits, and fire hazards. In coaxial cable the center conductor must be supported exactly in the middle of the hollow shield in order to prevent EM wave reflections. And any wires which present voltages higher than 60V can cause human shock and electrocution hazards.