Conductor fill may be up to what percent of the cross-sectional area in underfloor raceways?

The correct answer indicates that conductor fill in underfloor raceways can be up to 50% of the cross-sectional area. This standard is established to ensure safe and efficient installation of electrical conductors. When the fill is limited to 50%, it helps prevent overheating by allowing sufficient air circulation around the conductors, reducing the chances of temperature rise due to the accumulation of heat generated within the raceway.

Maintaining this fill percentage is crucial for maintaining the integrity of the electrical system and ensuring that conductors can carry their rated capacities without exceeding temperature limits. Proper fill standards also facilitate easier installation and future maintenance, including pulling or replacing conductors within the raceway.