Insulators make sure the energized parts do not touch the ground. All substation equipment in contact with an energized line or bus employs an insulator.
Disconnect switches establish isolation points to enable equipment maintenance. They are installed on both sides of the circuit breaker, high-side of the transformer, and on the line exit. Switches cannot and should not be used to interrupt load current or fault current. A switch operation takes place after the circuit is de-energized.