What boundary must energized electrical conductors be placed into a safe condition before work is performed?

The correct choice identifies the boundary known as the "limited approach" threshold, which is crucial for ensuring the safety of individuals working near energized electrical conductors. According to NFPA 70E, the limited approach boundary is intended to minimize the risk of electrical shock or arc flash injury.

When work is being performed on or near energized conductors, workers must maintain a safe distance defined by this boundary, which helps to ensure that they are not exposed to hazardous electrical conditions while carrying out their tasks. It's at the limited approach boundary that individuals may need to wear specific personal protective equipment (PPE) and follow defined safety procedures.

The other options represent different boundaries with distinct safety measures. The restricted approach boundary is closer to energized parts but requires additional safety measures such as the presence of a qualified person. The prohibited approach boundary indicates areas where no one should be unless they are properly qualified and equipped to be there, while the safe working distance is a general concept, not directly defined by NFPA 70E. Understanding the limited approach boundary is essential for electrical safety in the workplace, ensuring workers are safeguarded from potential electrical hazards.