No conductor larger than which AWG can be installed in a cellular concrete floor raceway without special permission?

The correct limit for conductor size in a cellular concrete floor raceway is 1/0 AWG. This is based on the National Electrical Code (NEC) guidelines, which provide specific restrictions on conductor sizes for different installation methods and scenarios. Cellular concrete floors are considered a unique environment for raceways, due to the constraints and potential risks associated with the installation of larger conductors.

Conduits and raceways meant for use in such applications are typically limited in size to ensure proper heat dissipation, minimize the risk of damage to the conductors, and maintain overall safety standards within the installation. If conductors larger than 1/0 AWG need to be utilized, special permission must be sought, typically involving additional considerations for safety and compliance with code requirements.

Understanding these limits is crucial for ensuring that electrical installations are both effective and safe, adhering to the NEC's requirements for different types of raceways and conductor installations.