When referring to wireway capacities, what is usually the metric used to determine fill limits?

The metric used to determine wireway fill limits is primarily the cross-sectional area. This measurement is critical because it allows for the assessment of how many conductors or wires can fit within the wireway without exceeding the maximum allowable fill limit. This is important to prevent overheating and ensure safe and efficient operation of the electrical system.

When calculating fill limits, the cross-sectional area of the conductors is compared to the cross-sectional area of the wireway itself. Properly accounting for this ensures compliance with safety regulations and standards, which aim to minimize the risk of electrical fires caused by overcrowding in wireways. Understanding cross-sectional area aids in selecting the appropriate wireway size for specific applications to maintain ratings and performance.