1. More rain all year round,humidity,salt fog heavier areas;
2. The working environment is humid,there is water vapor place;
3. Elevation of not more than 2000m;
4. The working environment contains sand dust,dust and other non-flammable dust;
5. The work environment contains weak acid,weak acid and other corrosive dust;
6. Lighting for energy-saving projects and maintenance of replacement of difficult places;
7. As oil, chemical, food, pharmaceutical, military, warehousing and other places flood lighting, projection lighting or street lighting.