Electrical metallic tubing shall be constructed of any of the following except:

Electrical metallic tubing (EMT) is commonly used for conducting electrical current and protecting electrical wiring. It is typically made from materials that provide the necessary structural integrity and electrical conductivity needed for safe electrical installations.

The correct response indicates that red brass is not a permissible material for EMT construction. Aluminum, steel, and stainless steel are all recognized materials suitable for EMT due to their strength, durability, and resistance to various environmental conditions.

Aluminum is lightweight and has good conductivity, making it suitable for use in certain applications where weight is a concern. Steel, particularly galvanized steel, is commonly used for its strength and resistance to corrosion. Stainless steel offers excellent corrosion resistance, making it appropriate for more demanding environments.

In contrast, red brass is generally not used for EMT construction since it is more often employed in different electrical applications, such as for fittings and connectors, rather than for the tubing itself. Red brass may also have properties, such as increased weight and cost, that make it less suitable for the standard applications of electrical metallic tubing.