Dry type transformers installed outdoors must have a?

• A. Raintight enclosure
• B. Weatherproof enclosure
• C. Waterproof enclosure
• D. Liquidtight enclosure

Answer: (B)

Outdoor installations face rain, snow, and moisture, so the enclosure for a dry-type transformer must be weatherproof to keep moisture out and protect insulation. Weatherproof means the enclosure is built to resist water intrusion from all directions under normal weather conditions, which is the level of protection required for equipment left outdoors (often aligning with outdoor-rated enclosures such as NEMA 3R).

A raintight enclosure is more limited, mainly focused on keeping rain out under certain conditions and may not address other weather factors like wind-driven rain or humidity. A waterproof enclosure implies being watertight to the point of submersion, which is more than what’s typically required for outdoor electrical equipment. A liquidtight enclosure relates to protection for connections involving liquidtight conduits, not the general weather protection of the transformer enclosure.