What is the largest conductor size allowed in cellular metal floor raceways without special permission?

The largest conductor size allowed in cellular metal floor raceways without requiring special permission is 1/0 AWG. This is established in the National Electrical Code (NEC), which governs electrical installations and outlines specific requirements for various types of raceways.

Cellular metal floor raceways are designed to accommodate wiring while maintaining accessibility and protection from physical damage. The restriction on conductor size aims to ensure that the raceways can properly handle the capacity and heat dissipation characteristics of the conductors installed inside them.

The 1/0 AWG size is the limit set forth by the code, providing a balance between functionality and safety within these specialized raceways. Conductors larger than this, such as 2/0 or 3/0 AWG, typically require additional considerations, which may include engineering assessments or modifications to ensure they do not compromise the safety and integrity of the raceway system.