What type of circuit wiring cannot be run through raceways according to the NEC?

Class 2 and Class 3 circuits are specifically designed for limited voltage and power levels, making them suitable for various low-power applications. According to the National Electrical Code (NEC), these types of circuits are generally restricted from being run through raceways. This is due to the potential for unintended interference and hazards that can arise when Class 2 and Class 3 circuits are bundled with other wiring types or run through conduits designed for service entrance or higher power circuits.

Class 1 circuits, on the other hand, can be run through raceways, as they typically include higher voltage levels and require more robust protection. Sensitive circuits, while they may have specific installation requirements, are not outright prohibited from raceway usage like Class 2 and Class 3 circuits. High voltage circuits need to follow specific guidelines regarding their installation and may be subject to unique voltage separation requirements, but they are not categorized in the same way as Class 2 and Class 3 circuits concerning raceway installation.

The focus on Class 2 and Class 3 circuits being unsuitable for raceways aligns with safety practices intended to mitigate the risk of interference and ensure compliance with NEC safety standards.