What critical precaution should be taken when working on live circuits?

Using protective equipment and following safety protocols is the most critical precaution when working on live circuits. This ensures maximum safety by minimizing the risk of electrical shock and other hazards associated with working near live electrical components. Protective equipment can include insulated gloves, safety goggles, dielectric footwear, and arc flash protective clothing, which help to safeguard the worker against potential electric arcs or accidental contact with live parts.

Moreover, following established safety protocols, such as verifying that circuits are de-energized before beginning work, employing lockout/tagout procedures, and ensuring that the work area is free of conductive materials, is essential. These protocols not only protect the individual performing the work but also mitigate possible hazards to others nearby.

The other options do not provide comprehensive protection. Wearing only gloves, using non-conductive tools, or working with one hand may contribute to safety, but none of these approaches encompass the full range of protective measures and safety protocols needed for the safe handling of live circuits.