Both NEMA 4 and NEMA 4X require comprehensive water and dust protection. Doors, frames, latches, gaskets, viewing windows, pushbuttons, cable glands, and removable panels must be engineered as an integrated system. NEMA 4 focuses on windblown dust, rain, sleet, snow, splashing water, and hose-directed water. NEMA 4X adds corrosion resistance to these capabilities.

NEMA 4X does not mandate a specific material, nor does it guarantee resistance to all chemicals. Coastal areas require protection against salt spray and moisture; food, beverage, and pharma zones must withstand detergents, disinfectants, and hot washdowns; chemical sites require data on media, concentration, temperature, and exposure time. Even with a corrosion-resistant body, latches, hinges, fasteners, grounding parts, welds, and cut edges remain vulnerable.

Material selection must also address galvanic corrosion, coating damage, gasket compatibility, and routine maintenance. If the enclosure includes fans, air conditioners, filters, or other thermal management accessories, verify they do not compromise overall ingress protection. For NEMA 4X procurement, specify exact material grades, finishes, fasteners, gasket types, and corrosion test criteria to avoid ambiguous "corrosion-resistant" claims.