Oil, dust, and rain tight. These enclosures are configured as Nema 12 devices when shipped from the factory and can be quickly converted to NEMA 3R by opening a weep hole and adding hubs as appropriate. NEMA Type 12 enclosures offer substantial protection for their cost. They are usually installed indoors, in typical “dirty” industrial environments where contamination by oil, dirt, dripping water, airborne dust and non-corrosive liquids is likely. These enclosures meet drip-, dust- and rust-resistance tests. NEMA Type 3R enclosures are intended for protected outdoor installations. They are rust-resistant and protect against falling (but not wind-blown) rain or sleet and against external icing, although cover mounted controls may be inoperable while the enclosure is ice covered. They are not designed to be dust-tight. The best outdoor installations offer protection — through building walls or shelters — from the wind.