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Table 110.28 covers enclosures for equipment rated 600 volts or less and describes what type of external environmental influence each type of enclosure is intended to withstand. For example, an indoor enclosure in a wet location might need to withstand a hose down for cleaning purposes, if that's something that it would be exposed to.
This is a very valuable table for selecting enclosures and for verifying that an appropriate enclosure has been selected. It can be used by the installer or designer and by the authority having jurisdiction.
Table110.28 uses the terms "raintight" and "rainproof" to describe various types of enclosures. A raintight or watertight enclosure will exclude water or rain. A rainproof or waterproof enclosure wouldn't necessarily exclude water entirely, but the enclosed equipment can continue to operate successfully even with a small amount of rain or water entering the enclosure. Similarly, external operators on enclosures suitable for sleet (Types 3S and 3SX), such as the handle of a disconnect, must continue to remain operable, even if the enclosure is covered with ice.
© Hughes Associates,Inc. 2012