An installation bottom base is provided. The installation bottom base includes: a main body, a fixed installation structure connected with the main body, a light source installation structure and a bottom base terminal assembly, and the bottom base terminal assembly includes at least two bottom base terminals exposed to the light source installation structure. When the light source module is installed to the bottom base, the at least two base terminals are electrically connected with the plurality of light emitting units in the light source module, so that at least two of the light emitting units in the light source module are in different power supply circuits. In summary, current supplied to the light emitting units by a power module is transmitted by the at least two terminals, so that the at least two light emitting units are in different power supply circuits.