What material or device prevents the conducting of electricity?

Explanation:

An insulator. You can see ceramic insulators on telephone poles and power poles if you look carefully. If you live in a city, somewhere in that city is a power station. The insulators are huge. They have to be. The currents are very large in many cases.

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees.