What is meant by a case, housing, or wall that prevents contact with energized parts?

A case, housing, or wall that prevents contact with energized parts is referred to as "enclosed." This terminology indicates that the design incorporates barriers that completely surround electrical components, effectively preventing any accidental contact. An enclosure serves a vital safety function, as it reduces the risk of electric shock, protects components from physical damage, and can also shield against environmental factors such as dust and moisture.

In electrical terminology, "enclosed" often implies a continuous structure that provides maximum protection. For instance, electrical enclosures are commonly used in various settings, including industrial and residential applications, to secure live electrical parts from inadvertent access.

The other options represent different approaches to safety around electrical components. "Shielded" typically refers to using materials to block electromagnetic interference rather than preventing physical contact. "Guarded" may refer to protective barriers that deter access, but may not fully encase the components. "Covered" suggests a simpler layer of protection, such as a lid or cover, which may not provide the complete protection that an enclosure does. Thus, the term "enclosed" is the most accurate way to describe a structure that prevents contact with energized parts.