Illumination using artificial light sources is common in these days. Many manufacturesare paying for the design of lamps depending on high efficacy and low UV hazards. Thisresearch is focusing on the most useable lamps in the Egyptian markets; high pressuremercury (HPM), metal Halide (MH), and high pressure sodium (HPS). A set up for relativespectral power distribution based on single monochromator and UVA silicon detector forabsolute irradiance measurements are used. The absolute irradiance in (W/m2) in UVA region of the lamps andtheir accompanied standard uncertainty are evaluated.