According to NFPA 70E, which circuits require testing or troubleshooting by qualified persons?

The requirement for testing or troubleshooting circuits per NFPA 70E is grounded in safety principles that focus on the hazards associated with electrical energy. NFPA 70E emphasizes that qualified persons, who are trained and knowledgeable in the risks and techniques to work with electrical equipment, are essential in ensuring safety when dealing with energized circuits.

In this context, circuits over 50 volts are considered to pose increased electrical hazards, which necessitates that only qualified individuals conduct testing or troubleshooting. This lower voltage threshold recognizes that even voltages above this level can lead to serious injuries or fatalities due to electric shock, arc flash, or arc blast. Therefore, working with circuits exceeding 50 volts requires specific training, proper equipment, and adherence to safety protocols outlined in NFPA 70E.

The other options, while they mention higher voltage limits, may not align with the primary safety threshold identified in NFPA 70E for requiring testing or troubleshooting by trained individuals. This ensures that personnel working on electrical systems can adequately identify hazards and employ safe work practices.