Which of the following can burn the insulation on the supply connections at the motor starter?

The insulation on the supply connections at the motor starter can be adversely affected by loose or poor connections. When connections are not secure, they can create resistance in the electrical circuit, which leads to increased heat generation at the point of connection. This excessive heat can cause the insulation material to deteriorate or burn, compromising the overall safety and functionality of the motor starter.

While other factors like high voltage supply, short circuits, or overheating of the motor can also lead to insulation damage, loose or poor connections are specifically significant because they create localized hotspots due to resistance. This makes them a direct cause of burning insulation in that context. Understanding the importance of maintaining proper, secure electrical connections is crucial for preventing insulation failure and ensuring reliable operation of electrical systems.