Prohibited practice when mounting electrical equipment is described by which term?

• A. Damp or wet locations
• B. Wooden plugs in masonry
• C. Natural circulation of air
• D. Gases, fumes and vapors, liquids

Answer: (B)

When mounting electrical equipment, you must use approved fasteners and methods that are listed for the substrate and environment. Wooden plugs in masonry are a prohibited practice because wood is not a reliable, listed mounting method for electrical gear in masonry. It can deteriorate with moisture, pests, or vibration and doesn’t provide the required strength or fire resistance. Proper masonry anchors—such as metal expansion anchors or chemical anchors—installed per the listing and manufacturer instructions are the correct approach.

The other options describe environmental or installation conditions (damp/wet locations, air circulation, or presence of gases/fumes/liquids) rather than a prohibited mounting practice, so they don’t indicate a mounting-method prohibition.