What should be done to all conductors before splicing?

Before splicing conductors, cleaning them with a wire brush is essential to ensure a proper and effective electrical connection. Conductors often have buildup of oxidation, dirt, or other contaminants that can impair the conductivity. Using a wire brush helps to remove these impurities, exposing clean metal surfaces which facilitates a strong and reliable splice.

Proper cleaning is critical because any residue might introduce resistance at the splice point, leading to overheating and potential failures in the circuit. A clean surface ensures maximum contact between the conductor ends, leading to lower resistance and better overall performance of the electrical system.

Other methods listed, such as polishing with sandpaper or coating with grease, do not provide the same level of direct cleaning and could potentially introduce new issues. Sandpaper might leave fine particles or create rough surfaces that do not sit well together. Grease could act as an insulator and hinder the electrical connection, which is counterproductive to achieving a strong splice. Leaving conductors untreated does not address the necessary cleaning and can lead to poor splicing results.