When calculating the conductor fill for strut-type channel raceway with external joiners, the raceway shall be permitted to be filled to which percent of the cross-sectional area?

The correct percentage for conductor fill in strut-type channel raceway with external joiners is based on the National Electrical Code (NEC) guidelines, which allow for a maximum fill of 60% of the cross-sectional area. This higher fill percentage is permitted because strut-type channels are designed to accommodate larger cables and more conductors, provided there is enough space for heat dissipation and to avoid overcrowding, which can lead to overheating and other safety issues.

Utilizing 60% of the cross-sectional area helps to ensure that the conductors can be installed adequately while maintaining the ability to handle electrical loads safely. Adhering to this guideline is essential for compliance with code requirements and for maintaining the reliability and safety of electrical installations.