An enclosure is required to prevent accidental contact with energized parts where bare terminals exist. This requirement applies to which of the following equipment?

• A. Transformers, switches, and motor controllers
• B. Lighting fixtures only
• C. Conductors in open air
• D. Grounding electrodes

Answer: (A)

Guarding against shock by keeping energized parts out of reach is the idea here. Transformers, switches, and motor controllers are the kinds of equipment that commonly have exposed live terminals accessible to someone who might touch them. An enclosure around these parts prevents accidental contact with the energized terminals, reducing the risk of electrical shock.

Lighting fixtures usually enclose the live parts inside a housing, but the hazard described focuses on bare terminals that could be touched in more utility-type equipment. Conductors in open air are not equipment with exposed terminals you’d enclose for touch protection in the same sense, and grounding electrodes aren’t energized parts normally accessible for touch. So the enclosure requirement applies to transformers, switches, and motor controllers because they more typically present bare terminals that could be touched.