Massachusetts Hoisting License Practice Test

When removing a battery from a diesel engine, which terminal should you disconnect first?

1. Positive

2. Negative

3. Ground

4. Accessory

The correct answer is: Negative

When removing a battery from a diesel engine, it is essential to disconnect the negative terminal first. This practice is crucial for safety reasons. Disconnecting the negative terminal helps to prevent any accidental short circuit that may occur when working with the battery. If the positive terminal is disconnected first and any metal tool inadvertently touches a grounded part of the engine or vehicle frame, it can create a direct pathway for current to flow, potentially causing sparks, damage, or even a fire. By removing the negative terminal first, the circuit is effectively broken, minimizing the risk of accidental discharges when working with or around the battery. The other options, such as positive, ground, and accessory terminals, do not provide the same level of safety during disconnection. Hence, while removing the battery, adhering to the practice of disconnecting the negative terminal first is a critical step for ensuring safety and preventing mishaps.