A gas-supplied illuminating appliance must be mounted on a post of what minimum size?

The correct answer, 2-1/2 inches, is based on the guidelines set forth in the National Fuel Gas Code, which outlines safety and installation standards for gas appliances. An illuminating appliance, which often includes fixtures that emit light using gas as the fuel source, requires a stable and secure mounting structure to ensure safe operation.

A post of this minimum size provides adequate support and stability, preventing tipping or other hazards associated with improper installation. Additionally, a 2-1/2 inch post strikes a balance between being strong enough to carry the load of the appliance while not being excessively large and cumbersome.

Insufficient post sizes, such as 2 inches, would likely not meet structural requirements, leading to potential safety concerns. Similarly, larger sizes such as 3 inches or 4 inches, although generally safe, may not be necessary and could lead to increased material costs without additional practical benefits for this application. Thus, 2-1/2 inches is the optimal and code-compliant size for mounting a gas-supplied illuminating appliance.