How often should electrical systems be inspected according to the NEC?

The National Electrical Code (NEC) provides guidelines for the safety and maintenance of electrical systems, emphasizing the importance of regular inspections. The correct choice highlights that electrical systems should be inspected periodically and after any significant renovations or installations. This ensures that any modifications made to the system are compliant with current safety standards and that the integrity of the system is maintained.

Periodic inspections help identify potential hazards, such as wear and tear, outdated components, or code violations. Additionally, after renovations or new installations, it is crucial to assess the entire system to ensure that it can safely handle the added load or changes. This proactive approach not only enhances safety but also helps in preventing issues before they arise, which is critical in maintaining a safe and efficient electrical environment.

The other options suggest fixed intervals or an approach based solely on problem reporting, which does not align with the NEC's recommendation for regular preventative maintenance and assessment. Regular inspections adapt to the specific conditions of an electrical system rather than adhering strictly to a set schedule.