Always use ___________ tools when working on or near circuits that must be energized.

Using insulated tools when working on or near energized circuits is essential for safety. Insulated tools are designed to prevent electric shock by providing a barrier between the user and any potential electric current. They have an insulating material that covers parts of the tool that may come in contact with live electrical components, significantly reducing the risk of accidental electrical conduction.

This is especially important in environments where circuits are energized, as the risk of severe injury or fatality from electrical shock is serious. Insulated tools must meet specific standards and ratings to ensure they can withstand high voltages, providing an additional level of protection for the technician.

The other options, while they may serve various purposes in a workshop setting, do not specifically address the critical safety needs associated with working on live circuits. Open-ended tools could create a risk if they touch two different live parts, threaded tools may not offer any insulation, and listed tools do not inherently suggest they have insulation to protect against electrical shock. Thus, insulated tools are the preferred and safest choice in these situations.