Final answer:
The correctness of requiring Atmospheric Vacuum Breakers (AVB) depends on specific situations and local codes. High-voltage wires on metal-frame towers are not insulated, inserting a dielectric in an air-filled capacitor does reduce the electric field, and large circuit breakers at high voltages face special challenges such as arcing.
Step-by-step explanation:
Regarding Atmospheric Vacuum Breakers (AVBs), the statement 'Atmospheric Vacuum Breakers (AVB) must be installed' is too general to be deemed true or false without context. AVBs are safety devices designed to prevent back siphonage of contaminated water into potable water systems in specific situations, such as lawn irrigation systems or commercial plumbing. Whether they must be installed depends on the application and local plumbing codes.
For the other questions presented:
The high-voltage wires connected to metal-frame towers are not wrapped in insulating material, making the statement false. These wires are held aloft by insulating connectors, but they are bare and not insulated due to high costs and impracticability at high voltages.
Inserting a dielectric between the plates of a capacitor reduces the electric field, so this statement is true.
Fuses and circuit breakers are critical for protecting electrical circuits from overload, but at high voltages, large circuit breakers face challenges such as arcing. Using insulating gas and gas jets to blow out sparks are methods employed to ensure safety and efficiency, especially in AC systems where the current goes through zero 120 times per second.