What should be checked on mechanical jumpers before using them?

Checking the ferrule connection and cleanliness of mechanical jumpers is vital before use because these factors directly impact the jumper's performance and safety. The ferrule connection is the part that connects the jumper to the conductor, and it must be secure to ensure a good electrical connection. A clean ferrule is important as dirt, grease, or corrosion can interfere with the electrical connection and lead to increased resistance, overheating, or failure of the connection.

Additionally, cleanliness helps prevent potential electrical faults or hazards that could occur if contaminants disrupt the flow of electricity. Ensuring both the integrity of the ferrule connection and the cleanliness of the components is crucial for maintaining the reliability and safety of the electrical system, making this the correct choice when preparing mechanical jumpers for use.