Why are the electric wires used in homes usually covered with materials like plastic or rubber?
To prevent shock.
Electric wires used in homes generally have a plastic or rubber covering so as to prevent shocks when we touch them. Our body can conduct electricity, so when we hold the current-carrying wire without any covering, the current flows through our body which gives us a shock. Without the covering, the wires may come in contact with each other and cause short-circuit as well.