The cubic inch rating of a No.18 fixture wire is how many cubic inches?

The cubic inch rating of a No. 18 fixture wire is 1.5 cubic inches. This value is established based on the NEC (National Electrical Code) guidelines for wire fill calculations, which determine how many conductors can be installed in a particular raceway or box without exceeding capacity limits for safety and efficiency.

For No. 18 wire, the cubic inch rating reflects the volume that a single fixture wire occupies, which aids electricians in ensuring that installations comply with code regulations regarding space and load. Understanding these ratings is essential for planning electrical installations to prevent overheating and to maintain safe working conditions.

The rating of 1.5 cubic inches is specifically important as it provides a standard measure that professionals depend on for proper installation and safety practices in wiring setups.