Which of the following is often critical when working with electrical circuits?

Using insulated tools is crucial when working with electrical circuits because these tools are specifically designed to prevent electrical shocks. Insulated tools have a protective covering that reduces the risk of electrical conduction, thereby safeguarding the technician from accidental contact with live wires or components. This is especially important in high-voltage environments where the risk of electric shock is significant. Insulated tools ensure that operators can perform their tasks safely while maintaining electrical integrity.

In contrast, wearing metal gloves would increase the risk of electrical shock as metal is a conductor. Having no voltage tester present can lead to dangerous situations where the technician may unknowingly work on live circuits, increasing the risk of injury or equipment damage. Additionally, operating without a breaker can expose circuits to overloads and faults, making the environment unsafe. Thus, using insulated tools is a fundamental safety practice in electrical work.