To determine when an installed bond has been properly adjusted, a technician should use which of the following?

Using a voltmeter is essential for determining when an installed bond has been properly adjusted because it measures the voltage drop across the bond connection. A proper bond should show a low voltage drop when a current is flowing through it, which indicates that the resistance is minimal and that the bond is effective in providing a low-resistance path for electrical current.

In applications related to corrosion control, ensuring that a bond is adjusted correctly is crucial for maintaining the integrity of the pipeline's protective coating. A significant voltage drop could indicate a bad connection, which can lead to corrosion issues.

Other instruments serve different purposes. A wattmeter measures power, which is not directly relevant to checking the effectiveness of a bond. An ohmmeter measures resistance, but may not provide the necessary context of voltage under operational conditions. An amperemeter measures current, which does not directly assess the voltage across the bond itself. The ability to measure voltage helps ensure that the bond is functioning correctly in the context of the entire system's electrical properties.