What type of plugs should not be used when mounting electrical equipment in masonry or similar materials?

When mounting electrical equipment in masonry or similar materials, wooden plugs are not suitable due to their poor performance and durability in such environments. Wood can absorb moisture, which can lead to degradation over time, affecting the integrity of the mounted equipment. Also, wooden plugs may not provide the necessary strength and stability required to securely hold electrical devices, especially in demanding installations where vibrations or environmental factors are present.

In contrast, metal, plastic, and ceramic plugs offer greater resistance to environmental changes and typically have better holding strength in rigid materials like masonry. Metal plugs are sturdy and can offer a secure mount, while plastic plugs are resistant to moisture and corrosion. Ceramic plugs, while less common, are also suitable for installations where electrical insulation and stability are needed. Therefore, wooden plugs should be avoided for these types of installations to ensure safety, reliability, and longevity.